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  • 1
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    Wiley-Blackwell
    Publication Date: 2018-01-06
    Description: Carrion beetles, Nicrophorus vespilloides, are reared on decomposing carrion where larvae are exposed to high populations of carcass-derived bacteria. Larvae do not become colonized with these bacteria but instead are colonized with the gut microbiome of their parents, suggesting that bacteria in the beetle microbiome outcompete the carcass-derived species for larval colonization. Here, we test this hypothesis and quantify the fitness consequences of colonization with different bacterial symbionts. First, we show that beetles colonized by their endogenous microbiome produce heavier broods than those colonized with carcass-bacteria. Next, we show that bacteria from the endogenous microbiome, including Providencia rettgeri and Morganella morganii , are better colonizers of the beetle gut and can outcompete nonendogenous species, including Serratia marcescens and Escherichia coli , during in vivo competition. Finally, we find that Providencia and Morganella provide beetles with colonization resistance against Serratia and thereby reduce Serratia -induced larval mortality. This effect is eliminated in larvae first colonized by Serratia , suggesting that while competition within the larval gut is determined by priority effects, these effects are less important for Serratia -induced mortality. Our work suggests that an unappreciated benefit of parental care in N. vespilloides is the social transmission of the microbiome from parents to offspring. Our work supports the idea that bacterial gut symbionts provide direct fitness benefits to Nicrophorus larvae by outcompeting potential bacterial pathogens. They further suggest that one benefit of parental care in Nicrophorus vespilloides is the social transmission of the microbiome from caring parents to their offspring.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 2
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    Wiley-Blackwell
    Publication Date: 2018-01-06
    Description: Rothstein (Behavioral Ecology and Sociobiology, 11, 1982, 229) was one of the first comprehensive studies to examine how different egg features influence egg rejection behaviors of avian brood parasite–hosts. The methods and conclusions of Rothstein (1982) laid the foundation for subsequent experimental brood parasitism studies over the past thirty years, but its results have never been evaluated with replication. Here, we partially replicated Rothstein's (1982) experiments using parallel artificial model egg treatments to simulate cowbird ( Molothrus ater ) parasitism in American robin ( Turdus migratorius ) nests. We compared our data with those of Rothstein (1982) and confirmed most of its original findings: (1) robins reject model eggs that differ from the appearance of a natural robin egg toward that of a natural cowbird egg in background color, size, and maculation; (2) rejection responses were best predicted by model egg background color; and (3) model eggs differing by two or more features from natural robin eggs were more likely to be rejected than model eggs differing by one feature alone. In contrast with Rothstein's (1982) conclusion that American robin egg recognition is not specifically tuned toward rejection of brown-headed cowbird eggs, we argue that our results and those of other recent studies of robin egg rejection suggest a discrimination bias toward rejection of cowbird eggs. Future work on egg recognition will benefit from utilizing a range of model eggs varying continuously in background color, maculation patterning, and size in combination with avian visual modeling, rather than using model eggs which vary only discretely. Avian brood parasite–hosts may recognize and remove brood parasite eggs from their nests as a defense mechanism. Here, we replicated egg recognition experiments using artificial eggs placed in American robin ( Turdus migratorius ) nests. Our results confirm many of S.I. Rothstein’s (Behavioral Ecology and Sociobiology, 11, 1982, 229) original findings and also reveal that American robins’ recognition of their own versus foreign eggs is likely driven by a discrimination bias toward rejection of brown-headed cowbird ( Molothrus ater ) eggs.
    Electronic ISSN: 2045-7758
    Topics: Biology
    Published by Wiley-Blackwell
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  • 3
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    Wiley-Blackwell
    Publication Date: 2018-01-06
    Description: There are a number of ecogeographical “rules” that describe patterns of geographical variation among organisms. The island rule predicts that populations of larger mammals on islands evolve smaller mean body size than their mainland counterparts, whereas smaller-bodied mammals evolve larger size. Bergmann's rule predicts that populations of a species in colder climates (generally at higher latitudes) have larger mean body sizes than conspecifics in warmer climates (at lower latitudes). These two rules are rarely tested together and neither has been rigorously tested in treeshrews, a clade of small-bodied mammals in their own order (Scandentia) broadly distributed in mainland Southeast Asia and on islands throughout much of the Sunda Shelf. The common treeshrew, Tupaia glis , is an excellent candidate for study and was used to test these two rules simultaneously for the first time in treeshrews. This species is distributed on the Malay Peninsula and several offshore islands east, west, and south of the mainland. Using craniodental dimensions as a proxy for body size, we investigated how island size, distance from the mainland, and maximum sea depth between the mainland and the islands relate to body size of 13 insular T. glis populations while also controlling for latitude and correlation among variables. We found a strong negative effect of latitude on body size in the common treeshrew, indicating the inverse of Bergmann's rule. We did not detect any overall difference in body size between the island and mainland populations. However, there was an effect of island area and maximum sea depth on body size among island populations. Although there is a strong latitudinal effect on body size, neither Bergmann's rule nor the island rule applies to the common treeshrew. The results of our analyses demonstrate the necessity of assessing multiple variables simultaneously in studies of ecogeographical rules. Although there are latitudinal and island effects on body size, neither Bergmann's rule nor the island rule applies to the common treeshrew. The results of our analyses demonstrate the necessity of assessing multiple variables simultaneously in studies of ecogeographical rules.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 4
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    Wiley-Blackwell
    Publication Date: 2018-01-07
    Description: Dysregulation of prefrontal cortical glutamatergic signalling via NMDA receptor hypofunction has been implicated in cognitive dysfunction and impaired inhibitory control in such neuropsychiatric disorders as schizophrenia, attention deficit hyperactivity disorder and drug addiction. Although NMDA receptors functionally interact with metabotropic glutamate receptor 5 (mGluR5), the consequence of this interaction for glutamate release in the prefrontal cortex (PFC) is unknown. We therefore investigated the effects of positive and negative allosteric mGluR5 modulation on changes in extracellular glutamate efflux in the medial PFC (mPFC) induced by systemic administration of the non-competitive NMDA receptor antagonist dizocilpine (or MK801) in rats. Extracellular glutamate efflux was measured following systemic administration of the positive allosteric mGluR5 modulator [S-(4-Fluoro-phenyl)-{3-[3-(4-fluoro-phenyl)-[1,2,4]-oxadiazol-5-yl]-piperidin-1-yl}-methanone] (ADX47273; 100 mg/kg, p.o.) and negative allosteric mGluR5 modulator [2-chloro-4-{[1-(4-fluorophenyl)-2,5-dimethyl-1H-imidazol-4-yl]ethynyl}pyridine] (RO4917523; 0.3 mg/kg, p.o.), using a wireless glutamate biosensor in awake, freely-moving rats. The effect of MK801 (0.03-0.06 mg/kg, s.c.) on mPFC glutamate efflux was also investigated in addition to the effects of MK801 (0.03 mg/kg, s.c.) following ADX47273 (100 mg/kg, p.o.) pre-treatment. ADX47273 produced a sustained increase in glutamate efflux and increased the effect of NMDA receptor antagonism on glutamate efflux in the mPFC. By contrast, negative allosteric mGluR5 modulation with RO4917523 decreased glutamate efflux in the mPFC. These findings indicate that positive and negative allosteric mGluR5 modulators produce long lasting and opposing actions on extracellular glutamate efflux in the mPFC. Positive and negative allosteric modulators of mGluR5 may therefore be viable therapeutic agents to correct abnormalities in glutamatergic signalling present in a range of neuropsychiatric disorders. This article is protected by copyright. All rights reserved.
    Print ISSN: 0022-3042
    Electronic ISSN: 1471-4159
    Topics: Medicine
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  • 5
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    Wiley-Blackwell
    Publication Date: 2018-01-09
    Description: Underground community assemblies have not been studied well compared with aboveground communities, despite their importance for our understanding of whole ecosystems. To investigate underground community assembly over evolutionary timescales, we examined terrestrial earthworm communities (Oligochaeta: Haplotaxida) in conserved mountainous primary forests in Japan as a model system. We collected 553 earthworms mostly from two dominant families, the Megascolecidae and the Lumbricidae, from 12 sites. We constructed a molecular taxonomic unit tree based on the analysis of three genes to examine the effects of a biogeographic factor (dispersal ability) and an evolutionary factor (habitat adaptation) on the earthworm community assembly process. The phylogenetic distance of the earthworm communities among sites was positively correlated with geographic distance when intraspecific variation was included, indicating that the divergence within species was affected by biogeographic factors. The community assembly process in the Megascolecidae has also been affected by environmental conditions in relation to an evolutionary relationship between habitat environment and intestinal cecum type, a trait closely related to habitat depth and diet, whereas that in the Lumbricidae has not been affected as such. Intestinal cecum type showed a pattern of niche conservatism in the Megascolecidae lineage. Our results suggest that investigating the evolution of a key trait related to life history can lead to the clear description of community assembly process over a long timescale and that the community assembly process can differ greatly among related lineages even though they live sympatrically. To investigate underground community assembly over evolutionary time scales, we examined terrestrial earthworm communities (Oligochaeta: Haplotaxida) in conserved mountainous primary forests in Japan. Our study shows that the community assembly process in the Megascolecidae, which is one of the two dominant families in Japan, has been affected by environmental factors in relation to an evolutionary relationship between habitat environment and intestinal cecum type, a trait closely related to habitat depth and diet, whereas that in the Lumbricidae has not been affected as such. Our results suggest that investigating the evolution of a key trait related to life history can lead to the clear description of community assembly process and that the community assembly process can differ greatly among related lineages even though they live sympatrically.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 6
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    Wiley-Blackwell
    Publication Date: 2018-01-09
    Description: Understanding local adaptation of tree populations to climate allows the development of assisted migration guidelines as a tool for forest managers to address climate change. Here, we study the relationship among climate, a wide range of physiological traits, and field performance of selected white spruce provenances originating from throughout the species range. Tree height, survival, cold hardiness, hydraulic, and wood anatomical traits were measured in a 32-year-old common garden trial, located in the center of the species range. Provenance performance included all combinations of high versus low survival and growth, with the most prevalent population differentiation for adaptive traits observed in cold hardiness. Cold hardiness showed a strong association with survival and was associated with cold winter temperatures at the site of seed origin. Tree height was mostly explained by the length of the growing season at the origin of the seed source. Although population differentiation was generally weak in wood anatomical and hydraulic traits, within-population variation was substantial in some traits, and a boundary analysis revealed that efficient water transport was associated with vulnerable xylem and low wood density, indicating that an optimal combination of high water transport efficiency and high cavitation resistance is not possible. Our results suggest that assisted migration prescriptions may be advantageous under warming climate, but pronounced trade-offs between survival and cold hardiness require a careful consideration of the distances of these transfers. In this study, we study relationships between climate, a wide range of physiological traits, and field performance of selected white spruce provenances in a common garden. We observed a strong influence of fall hardiness in tree mortality while tree growth was mostly explained by growing season length. These results will help develop assisted migration prescriptions to mitigate the climate change impact in our forests.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 7
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    Wiley-Blackwell
    Publication Date: 2018-01-09
    Description: Fire exclusion in eastern North American Quercus–Carya woodlands has resulted in overstory compositional changes, linked to altered fuel composition, structure, and ultimately, altered fire regimes. These compositional changes have been implicated in a dampening effect on fire behavior in formerly fire-prone ecosystems, the positive feedback termed “mesophication.” Several proposed mechanisms are likely involved in this process; however, few have been examined. We evaluated the potential mechanism of dampened forest floor flammability through changes in litter composition in a southeastern U.S. oak–hickory forest undergoing mesophication. Laboratory drying and burning experiments revealed that increasing the relative contribution of litter from fire-sensitive mesophytic tree species ( Liquidambar styraciflua , Ulmus alata , and Cornus florida ) increased moisture retention and diminished litter flammability. Litterbeds composed of ≥66% mesophyte litter gained the most moisture following fuelbed saturation and were consistently wetter than pyrophyte litter following 12 and 24 h of drying. Flammability metrics decreased with increasing contribution of mesophyte litter with reductions most pronounced under more moist conditions. Under dry conditions, where litter moisture did not differ across compositional treatments, mesophyte litter was less flammable than fuelbeds that contained any pyrophyte litter. The combined effects of moisture retention and less flammable litter reveal an important synergistic impact that may result with increased dominance of fire-sensitive mesophytic species. Restoration efforts in long-unburned eastern hardwood forests may require altering stand composition to limit mesophytic litter input or developing burn prescriptions that intensify surface fire behavior in less flammable fuels.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 8
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    Wiley-Blackwell
    Publication Date: 2018-01-09
    Description: Inherited CTPS1, CD27, and CD70 deficiencies in humans have revealed key factors of T-lymphocyte expansion, a critical prerequisite for an efficient immunity to Epstein–Barr virus (EBV) infection. RASGRP1 is a T-lymphocyte-specific nucleotide exchange factor known to activate the pathway of MAP kinases (MAPK). A deleterious homozygous mutation in RASGRP1 leading to the loss RASGRP1 expression was identified in two siblings who both developed a persistent EBV infection leading to Hodgkin lymphoma. RASGRP1-deficient T cells exhibited defective MAPK activation and impaired proliferation that was restored by expression of wild-type RASGRP1. Similar defects were observed in T cells from healthy individuals when RASGRP1 was downregulated. RASGRP1-deficient T cells also exhibited decreased CD27-dependent proliferation toward CD70-expressing EBV-transformed B cells, a crucial pathway required for expansion of antigen-specific T cells during anti-EBV immunity. Furthermore, RASGRP1-deficient T cells failed to upregulate CTPS1, an important enzyme involved in DNA synthesis. These results show that RASGRP1 deficiency leads to susceptibility to EBV infection and demonstrate the key role of RASGRP1 at the crossroad of pathways required for the expansion of activated T lymphocytes. RASGRP1 deficiency is characterized by a high susceptibility to develop Epstein-Barr virus (EBV)-driven B-cell lymphoproliferative disorders such as B-cell lymphoma like Hodgkin lymphoma. This is caused by defective expansion of activated T cells required for an efficient immune response to EBV.
    Print ISSN: 1757-4676
    Electronic ISSN: 1757-4684
    Topics: Medicine
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  • 9
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    Wiley-Blackwell
    Publication Date: 2018-01-09
    Description: Peripheral myelin protein 22 (PMP22) is a component of compact myelin in the peripheral nervous system. The amount of PMP22 in myelin is tightly regulated, and PMP22 over or under-expression cause Charcot-Marie-Tooth 1A (CMT1A) and Hereditary Neuropathy with Pressure Palsies (HNPP). Despite the importance of PMP22 , its function remains largely unknown. It was reported that PMP22 interacts with the β4 subunit of the laminin receptor α6β4 integrin, suggesting that α6β4 integrin and laminins may contribute to the pathogenesis of CMT1A or HNPP. Here we asked if the lack of α6β4 integrin in Schwann cells influences myelin stability in the HNPP mouse model. Our data indicate that PMP22 and β4 integrin may not interact directly in myelinating Schwann cells, however, ablating β4 integrin delays the formation of tomacula, a characteristic feature of HNPP. In contrast, ablation of integrin β4 worsens nerve conduction velocities and non-compact myelin organization in HNPP animals. This study demonstrates that indirect interactions between an extracellular matrix receptor and a myelin protein influence the stability and function of myelinated fibers. This article is protected by copyright. All rights reserved.
    Print ISSN: 0022-3042
    Electronic ISSN: 1471-4159
    Topics: Medicine
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  • 10
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    Wiley-Blackwell
    Publication Date: 2018-01-09
    Description: Loss of function mutations of DJ-1 ( PARK7 ) have been linked to the pathogenesis of Parkinson disease (PD). Antioxidative stress is one of the multi-protective functions of DJ-1, and oxidation of cysteine 106 (Cys106) has been proposed to regulate the protective activity of DJ-1. Uncoupling protein 4 (UCP4) is located in the inner membrane of mitochondria and functions to protect against oxidative stress. In this study, we used neuronal (SH-SY5Y) cells and DJ-1 knockout (KO) mice to elucidate whether DJ-1 regulated oxidative stress via modulating the expression of UCP4, and the underlying mechanism. The downstream products of oxidative stress, mitochondrial membrane potential (ΔΨm) and cell viability were also investigated. We found that UCP4 was up regulated upon 1-methyl-4-phenylpyridinium (MPP + ) stimulation in SH-SY5Y cells, which was enhanced by wild type DJ-1 and alleviated by DJ-1 knockdown. Expression of UCP4 in DJ-1 KO mice was lower compared with wild type mice. In addition, up-regulation of UCP4 was alleviated by inhibition of oxidized DJ-1, and enhanced by increase of oxidized DJ-1 under conditions of oxidative stress using western blot analysis. Moreover, overexpression of UCP4 in DJ-1 knockdown cells partially reversed the decrease of cell viability, ΔΨm, as well as the increase of products of oxidative stress upon MPP + stimulation. Further analysis showed that DJ-1 regulated transcriptional activity of UCP4 partially via Nuclear factor-kappa B (NF-κB) pathway in the presence of MPP + . Together, our results suggested DJ-1 might regulate the expression of UCP4 by oxidation of DJ-1 and partially via NF-κB pathway in its protective response to oxidative stress. This article is protected by copyright. All rights reserved.
    Print ISSN: 0022-3042
    Electronic ISSN: 1471-4159
    Topics: Medicine
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  • 11
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    Wiley-Blackwell
    Publication Date: 2018-01-10
    Description: Residues of pharmaceuticals are increasingly detected in surface waters throughout the world. In four streams in Baltimore, Maryland, USA, we detected analgesics, stimulants, antihistamines, and antibiotics using passive organic samplers. We exposed biofilm communities in these streams to the common drugs caffeine, cimetidine, ciprofloxacin, and diphenhydramine. Respiration rates in the least urban stream were suppressed when exposed to these drugs, but biofilm functioning in the most urban stream was resistant to drug exposure. Exposure to the antibiotic ciprofloxacin altered bacterial community composition at all sites, with the greatest change occurring in the most urban stream. These results indicated that continuous exposure to drugs in urban streams may select for sub-populations of highly resistant bacteria that maintain community function in response to urban contaminants.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 12
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    Wiley-Blackwell
    Publication Date: 2018-01-10
    Print ISSN: 0022-3042
    Electronic ISSN: 1471-4159
    Topics: Medicine
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  • 13
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    Wiley-Blackwell
    Publication Date: 2018-01-11
    Description: Key Points The DMP-1 study examined women in the United States who were counseled regarding the use of SERMs as part of their regular care. Patient perceptions regarding drug-based therapy played an important role in the choice of therapy. The findings suggest that HCPs should not only present medical information, but also communicate with patients regarding their beliefs and experiences.
    Print ISSN: 0007-9235
    Electronic ISSN: 1542-4863
    Topics: Medicine
    Published by Wiley-Blackwell on behalf of American Cancer Society.
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  • 14
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    Wiley-Blackwell
    Publication Date: 2018-01-13
    Description: Inbreeding is widely hypothesized to shape mating systems and population persistence, but such effects will depend on which traits show inbreeding depression. Population and evolutionary consequences could be substantial if inbreeding decreases sperm performance and hence decreases male fertilization success and female fertility. However, the magnitude of inbreeding depression in sperm performance traits has rarely been estimated in wild populations experiencing natural variation in inbreeding. Further, the hypothesis that inbreeding could increase within-ejaculate variation in sperm traits and thereby further affect male fertilization success has not been explicitly tested. We used a wild pedigreed song sparrow ( Melospiza melodia ) population, where frequent extrapair copulations likely create strong postcopulatory competition for fertilization success, to quantify effects of male coefficient of inbreeding ( f ) on key sperm performance traits. We found no evidence of inbreeding depression in sperm motility, longevity, or velocity, and the within-ejaculate variance in sperm velocity did not increase with male f . Contrary to inferences from highly inbred captive and experimental populations, our results imply that moderate inbreeding will not necessarily constrain sperm performance in wild populations. Consequently, the widely observed individual-level and population-level inbreeding depression in male and female fitness may not stem from reduced sperm performance in inbred males. In a natural population of song sparrows, we detected no deleterious effects of inbreeding on sperm performance. Our study suggests that inbreeding depression in male gametic performance might not be a primary driver of inbreeding depression in male or female fitness in wild populations.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 15
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    Wiley-Blackwell
    Publication Date: 2018-01-13
    Description: Evolutionary radiations are responsible for much of Earth's diversity, yet the causes of these radiations are often elusive. Determining the relative roles of adaptation and geographic isolation in diversification is vital to understanding the causes of any radiation, and whether a radiation may be labeled as “adaptive” or not. Across many groups of plants, trait–climate relationships suggest that traits are an important indicator of how plants adapt to different climates. In particular, analyses of plant functional traits in global databases suggest that there is an “economics spectrum” along which combinations of functional traits covary along a fast–slow continuum. We examine evolutionary associations among traits and between trait and climate variables on a strongly supported phylogeny in the iconic plant genus Protea to identify correlated evolution of functional traits and the climatic-niches that species occupy. Results indicate that trait diversification in Protea has climate associations along two axes of variation: correlated evolution of plant size with temperature and leaf investment with rainfall. Evidence suggests that traits and climatic-niches evolve in similar ways, although some of these associations are inconsistent with global patterns on a broader phylogenetic scale. When combined with previous experimental work suggesting that trait–climate associations are adaptive in Protea , the results presented here suggest that trait diversification in this radiation is adaptive. Trait-climate associations are often indicators for the role of adaptation of plants to the abiotic environments which they occupy. The morphologically diverse and species-rich genus Protea is an iconic plant radiation centered in the climatically heterogeneous Cape Floristic Region. Examination of present day and evolutionary associations between traits and climate variables on a strongly supported phylogeny indicates that diversification in Protea has correlated evolution along two distinct axes of variation, with correlated evolution of plant size with temperature and leaf investment with rainfall.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 16
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    Wiley-Blackwell
    Publication Date: 2018-01-14
    Description: Mating systems have broad impacts on how sexual selection and mate choice operate within a species, but studies of mating behavior in the laboratory may not reflect how these processes occur in the wild. Here, we examined the mating behavior of the neotropical butterfly Heliconius erato in the field by releasing larvae and virgin females and observing how they mated. H. erato is considered a pupal-mating species (i.e., males mate with females as they emerge from the pupal case). However, we observed only two teneral mating events, and experimentally released virgins were almost all mated upon recapture. Our study confirms the presence of some pupal-mating behavior in H. erato , but suggests that adult mating is likely the prevalent mating strategy in this species. These findings have important implications for the role of color pattern and female mate choice in the generation of reproductive isolation in this diverse genus. Heliconius erato is thought to be one of a few species of butterfly which display an unusual mating system known as pupal mating: males wait on the developing pupae of females and mate with them upon emergence. Using experiments and observations with natural populations, we find that while H. erato do engage in pupal mating in the wild, it is rare: adult-mating is likely the prevalent mode of mating. Our finding that most couplings occur between adults suggests that color pattern is likely an important factor driving assortative mating and speciation in this adaptively radiating species.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 17
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    Wiley-Blackwell
    Publication Date: 2018-01-16
    Description: Salivary gland acinar cells are routinely destroyed during radiation treatment for head and neck cancer that results in a lifetime of hyposalivation and co-morbidities. A potential regenerative strategy for replacing injured tissue is the reactivation of endogenous stem cells by targeted therapeutics. However, the identity of these cells, whether they are capable of regenerating the tissue, and the mechanisms by which they are regulated are unknown. Using in vivo and ex vivo models, in combination with genetic lineage tracing and human tissue, we discover a SOX2 + stem cell population essential to acinar cell maintenance that is capable of replenishing acini after radiation. Furthermore, we show that acinar cell replacement is nerve dependent and that addition of a muscarinic mimetic is sufficient to drive regeneration. Moreover, we show that SOX2 is diminished in irradiated human salivary gland, along with parasympathetic nerves, suggesting that tissue degeneration is due to loss of progenitors and their regulators. Thus, we establish a new paradigm that salivary glands can regenerate after genotoxic shock and do so through a SOX2 nerve-dependent mechanism. Salivary glands regenerate after radiation injury through SOX2-mediated secretory acinar cell replacement as shown using genetic lineage tracing and ablation methods, in combination with in vivo and ex vivo gamma radiation-induced damage models.
    Print ISSN: 1757-4676
    Electronic ISSN: 1757-4684
    Topics: Medicine
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  • 18
    Publication Date: 2018-01-16
    Description: Current knowledge of yield potential and best agronomic management practices for perennial bioenergy grasses is primarily derived from small-scale and short-term studies, yet these studies inform policy at the national scale. In an effort to learn more about how bioenergy grasses perform across multiple locations and years, the U.S. Department of Energy (US DOE)/Sun Grant Initiative Regional Feedstock Partnership was initiated in 2008. The objectives of the Feedstock Partnership were to (1) provide a wide range of information for feedstock selection (species choice) and management practice options for a variety of regions and (2) develop national maps of potential feedstock yield for each of the herbaceous species evaluated. The Feedstock Partnership expands our previous understanding of the bioenergy potential of switchgrass, Miscanthus, sorghum, energycane, and prairie mixtures on Conservation Reserve Program land by conducting long-term, replicated trials of each species at diverse environments in the U.S. Trials were initiated between 2008 and 2010 and completed between 2012 and 2015 depending on species. Field-scale plots were utilized for switchgrass and Conservation Reserve Program trials to use traditional agricultural machinery. This is important as we know that the smaller scale studies often overestimated yield potential of some of these species. Insufficient vegetative propagules of energycane and Miscanthus prohibited farm-scale trials of these species. The Feedstock Partnership studies also confirmed that environmental differences across years and across sites had a large impact on biomass production. Nitrogen application had variable effects across feedstocks, but some nitrogen fertilizer generally had a positive effect. National yield potential maps were developed using PRISM-ELM for each species in the Feedstock Partnership. This manuscript, with the accompanying supplemental data, will be useful in making decisions about feedstock selection as well as agronomic practices across a wide region of the country. Maximum average annual yield potential of herbaceous feedstocks (switchgrass, Miscanthus, sorghum, energycane, and Conservation Reserve Program mixtures) across the continental United States. Yield potential shown on this map is that of the highest of all species evaluated at a given location in the United States. This map was generated using the PRISM-ELM model and is based in part on data from Feedstock Partnership Field Trials.
    Print ISSN: 1757-1693
    Electronic ISSN: 1757-1707
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 19
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    Wiley-Blackwell
    Publication Date: 2018-01-17
    Description: The response of tropical forests to global warming is one of the largest uncertainties in predicting the future carbon balance of Earth. To determine the likely effects of elevated temperatures on tropical forest understory plants and soils, as well as other ecosystems, an infrared (IR) heater system was developed to provide in situ warming for the Tropical Responses to Altered Climate Experiment (TRACE) in the Luquillo Experimental Forest in Puerto Rico. Three replicate heated 4-m-diameter plots were warmed to maintain a 4°C increase in understory vegetation compared to three unheated control plots, as sensed by IR thermometers. The equipment was larger than any used previously and was subjected to challenges different from those of many temperate ecosystem warming systems, including frequent power surges and outages, high humidity, heavy rains, hurricanes, saturated clayey soils, and steep slopes. The system was able to maintain the target 4.0°C increase in hourly average vegetation temperatures to within ± 0.1°C. The vegetation was heterogeneous and on a 21° slope, which decreased uniformity of the warming treatment on the plots; yet, the green leaves were fairly uniformly warmed, and there was little difference among 0–10 cm depth soil temperatures at the plot centers, edges, and midway between. Soil temperatures at the 40–50 cm depth increased about 3°C compared to the controls after a month of warming. As expected, the soil in the heated plots dried faster than that of the control plots, but the average soil moisture remained adequate for the plants. The TRACE heating system produced an adequately uniform warming precisely controlled down to at least 50-cm soil depth, thereby creating a treatment that allows for assessing mechanistic responses of tropical plants and soil to warming, with applicability to other ecosystems. No physical obstacles to scaling the approach to taller vegetation (i.e., trees) and larger plots were observed. An infrared heater system was designed, installed, and tested over tropical forest understory vegetation in Puerto Rico. Larger plots and a higher degree of warming required using 4–8 times larger equipment than used for this application before, and the location involved challenges from power surges and outages, high humidity, steep slope, weak soils, and hurricanes. The system maintained the target 4°C rise in temperature of the heated plots above that of the controls when power was available, the uniformity of the treatment was satisfactory, and significant soil warming of 2.6°C on average to a depth of 50 cm was achieved with minimal soil drying.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 20
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    Wiley-Blackwell
    Publication Date: 2018-01-17
    Description: Fluctuations in marine populations often relate to the supply of recruits by oceanic currents. Variation in these currents is typically driven by large-scale changes in climate, in particular ENSO (El Nino Southern Oscillation). The dependence on large-scale climatic changes may, however, be modified by early life history traits of marine taxa. Based on eight years of annual surveys, along 150 km of coastline, we examined how ENSO influenced abundance of juvenile fish, coral spat, and canopy-forming macroalgae. We then investigated what traits make populations of some fish families more reliant on the ENSO relationship than others. Abundance of juvenile fish and coral recruits was generally positively correlated with the Southern Oscillation Index (SOI), higher densities recorded during La Niña years, when the ENSO-influenced Leeuwin Current is stronger and sea surface temperature higher. The relationship is typically positive and stronger among fish families with shorter pelagic larval durations and stronger swimming abilities. The relationship is also stronger at sites on the coral back reef, although the strongest of all relationships were among the lethrinids ( r  = .9), siganids ( r  = .9), and mullids ( r  = .8), which recruit to macroalgal meadows in the lagoon. ENSO effects on habitat seem to moderate SOI–juvenile abundance relationship. Macroalgal canopies are higher during La Niña years, providing more favorable habitat for juvenile fish and strengthening the SOI effect on juvenile abundance. Conversely, loss of coral following a La Niña-related heat wave may have compromised postsettlement survival of coral dependent species, weakening the influence of SOI on their abundance. This assessment of ENSO effects on tropical fish and habitat-forming biota and how it is mediated by functional ecology improves our ability to predict and manage changes in the replenishment of marine populations. Abundance of juvenile fish and coral recruits was generally positively correlated with the Southern Oscillation Index (SOI), with higher densities recorded during La Niña years. The relationship is typically positive and stronger among fish families with shorter pelagic larval durations and stronger swimming abilities. ENSO effects on habitat seem to moderate SOI–juvenile abundance relationship.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 21
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    Wiley-Blackwell
    Publication Date: 2018-01-17
    Description: The endosymbiotic bacterium Wolbachia infects a wide range of arthropods and their relatives. It is an intracellular parasite transmitted through the egg from mother to offspring. Wolbachia can spread and persist through various means of host reproductive manipulation. How these different mechanisms of host manipulation evolved in Wolbachia is unclear. Which host reproductive phenotype is most likely to be ancestral and whether evolutionary transitions between some host phenotypes are more common than others remain unanswered questions. Recent studies have revealed multiple cases where the same Wolbachia strain can induce different reproductive phenotypes in different hosts, raising the question to what degree the induced host phenotype should be regarded as a trait of Wolbachia . In this study, we constructed a phylogenetic tree of Wolbachia and analyzed the patterns of host phenotypes along that tree. We were able to detect a phylogenetic signal of host phenotypes on the Wolbachia tree, indicating that the induced host phenotype can be regarded as a Wolbachia trait. However, we found no clear support for the previously stated hypothesis that cytoplasmic incompatibility is ancestral to Wolbachia in arthropods. Our analysis provides evidence for heterogeneous transition rates between host phenotypes. This study uses comparative methods to analyze the evolution of Wolbachia -induced host reproductive phenotypes along the phylogenetic tree of Wolbachia . Our results show that Wolbachia -induced host reproductive phenotypes can be regarded as a Wolbachia trait and provide novel insights into ancestral states and evolutionary transition rates of Wolbachia 's host manipulation.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 22
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    Wiley-Blackwell
    Publication Date: 2018-01-17
    Description: This article reviews the scholarly literature dealing with the perennial multipurpose crop Virginia mallow ( Sida hermaphrodita (L.) Rusby; Sida in the following). In regions dominated by intensive agricultural management practices, growing Sida holds the potential to combine ecosystem services such as decreasing soil erosion, reducing nitrate leaching as well as enhancing biodiversity, with economic profit for the farmer. After promising biomass yields of Sida were reported from studies performed in Poland about 15 years ago, the interest in this plant species has continuously increased, and different utilization pathways were examined, predominantly by researchers in Poland and Germany. At present, however, a comprehensive overview that summarizes the different lines of research performed regarding the use of Sida is lacking. This review aims at closing this gap. After providing background information on Sida , we summarize the main results obtained from investigations concerning biomass yields, fertilization effects, key findings concerning direct combustion, biogas production, steam gasification, phytoremediation, and alternative utilization pathways. Thereafter, we highlight important aspects of Virginia mallow cultivation practices, including first estimates regarding the costs involved. Finally, we point to existing research gaps. Summarizing the available literature on Sida , we aim at raising the interest of scientists and farmers in this plant species further and to show where future research might tie in with, as the successful cultivation of Sida might represent a worthwhile strategy to transform current agricultural practices in Central Europe into approaches that are more sustainable and resilient against future challenges. This article is protected by copyright. All rights reserved.
    Print ISSN: 1757-1693
    Electronic ISSN: 1757-1707
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 23
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    Wiley-Blackwell
    Publication Date: 2018-01-17
    Description: The importance and prevalence of phylogenetic tracking between hosts and dependent organisms caused by co-evolution and shifting between closely related host species have been debated for decades. Most studies of phylogenetic tracking among phytophagous insects and their host plants have been limited to insects feeding on a narrow range of host species. However, narrow host ranges can confound phylogenetic tracking (phylogenetic tracking hypothesis) with host shifting between hosts of intermediate relationship (intermediate hypothesis). Here, we investigated the evolutionary history of the Enchenopa binotata complex of treehoppers. Each species in this complex has high host fidelity, but the entire complex uses hosts across eight plant orders. The phylogenies of E. binotata were reconstructed to evaluate whether (1) tracking host phylogeny; or (2) shifting between intermediately related host plants better explains the evolutionary history of E. binotata . Our results suggest that E. binotata primarily shifted between both distant and intermediate host plants regardless of host phylogeny and less frequently tracked the phylogeny of their hosts. These findings indicate that phytophagous insects with high host fidelity, such as E. binotata , are capable of adaptation not only to closely related host plants but also to novel hosts, likely with diverse phenology and defense mechanisms. Although with high host fidelity and a wide range of host usage (across eight host orders), we found that host shifting, regardless of the host plant relationship, played a more important role than coevolution with hosts in the evolutionary history of Enchenopa binotata treehoppers. This result is fascinating it is not only unsupportive to coevolution between plant–insect relationship, but is also unsupportive to intermediate hypothesis for host shifting.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 24
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    Wiley-Blackwell
    Publication Date: 2018-01-17
    Description: Translocations have become an increasingly valuable tool for conservation in recent years, but assessing the successfulness of translocations and identifying factors that contribute to their success continue to challenge biologists. As a unique class of translocation, population reinforcements have received relatively little attention despite representing a substantial portion of translocation programs. Here, we conducted population viability analyses to quantify the effects of 216 reinforcement scenarios on the long-term viability of four populations of Greater Prairie-Chickens ( Tympanuchus cupido pinnatus ) in Wisconsin, USA, and used multiple linear regression to identify factors that had the greatest relative influence on population viability. We considered reinforcements from outside of the study area in addition to translocations among Wisconsin populations. We observed the largest decreases in site-specific extinction probability and the largest increases in the number of sites persisting for 50 years when more vulnerable populations were targeted for reinforcement. Conversely, reinforcing the most stable sites caused the greatest reduction in regional extinction probability. We found that the number of translocated hens was a comparatively poor predictor of changes in long-term population viability, whereas the earlier onset of reinforcement was consistently associated with the greatest increases in viability. Our results highlight the value of evaluating alternative reinforcement strategies a priori and considering the effects of reinforcement on metrics of long-term population persistence. We used a combination of population viability analysis and linear regression techniques to compare 216 reinforcement scenarios for four populations of the threatened Greater Prairie-Chicken ( Tympanuchus cupido pinnatus ) in central Wisconsin, USA. We considered three different metrics of long-term population viability and identified factors that were most strongly associated with population persistence. Early onset of reinforcement efforts was a much stronger predictor of long-term translocation success than release cohort size.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 25
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    Wiley-Blackwell
    Publication Date: 2018-01-17
    Description: Salmon–bear ecosystems that historically existed throughout most of the northern temperate and boreal regions of planet earth now persist only in the North Pacific. Extensive research on salmon–bear interactions has focused on the role that bears ( Ursus arctos and U. americanus ) play in provisioning terrestrial systems with marine-derived nutrients, but little attention has been paid to how the much higher bear population densities in salmon-bearing ecosystems then affect ecological communities. Salmon-supported brown bears secondarily consume large quantities of fruit and may thus serve as important seed dispersers, but the relative seed dispersal services provided by bears and birds are unknown. We sought to (1) quantify the number of seeds dispersed by bears relative to birds, and (2) by brown bears relative to black bears, and to (3) assess whether the two sympatric bears temporally partition berry resources as a result of competitively dominant brown bears switching to feed on salmon, thus opening niche space for black bears. We used a combination of motion-triggered camera traps and environmental DNA (eDNA) from residual saliva to quantify the roles of birds, black bears, and brown bears as seed dispersers of devil's club ( Oplopanax horridus ), the dominant understory shrub at our field site in northern southeast Alaska. Brown bears were the numerically dominant seed dispersers, particularly before salmon became widely available, after which black bears became common seed dispersers, likely due to alleviation of interference competition. Birds accounted for only a small fraction of seed dispersal. This is the first demonstration of a temperate plant being primarily dispersed by mammalian gut passage. Our results suggest that bears are uniquely important seed dispersers, which may influence plant community composition in salmon-bearing ecosystems.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 26
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    Wiley-Blackwell
    Publication Date: 2018-01-17
    Description: “Financial toxicity” has now become a familiar term used in the discussion of cancer drugs, and it is gaining traction in the literature given the high price of newer classes of therapies. However, as a phenomenon in the contemporary treatment and care of people with cancer, financial toxicity is not fully understood, with the discussion on mitigation mainly geared toward interventions at the health system level. Although important, health policy prescriptions take time before their intended results manifest, if they are implemented at all. They require corresponding strategies at the individual patient level. In this review, the authors discuss the nature of financial toxicity, defined as the objective financial burden and subjective financial distress of patients with cancer, as a result of treatments using innovative drugs and concomitant health services. They discuss coping with financial toxicity by patients and how maladaptive coping leads to poor health and nonhealth outcomes. They cover management strategies for oncologists, including having the difficult and urgent conversation about the cost and value of cancer treatment, availability of and access to resources, and assessment of financial toxicity as part of supportive care in the provision of comprehensive cancer care. CA Cancer J Clin 2018 . © 2018 American Cancer Society .
    Print ISSN: 0007-9235
    Electronic ISSN: 1542-4863
    Topics: Medicine
    Published by Wiley-Blackwell on behalf of American Cancer Society.
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  • 27
    Publication Date: 2018-01-17
    Description: Targeting phylogenetic diversity (PD) in systematic conservation planning is an efficient way to minimize losses across the Tree of Life. Considering representation of genetic diversity below and above species level, also allows robust analyses within systems where taxonomy is in flux. We use dense sampling of phylogeographic diversity for eleven lizard genera, to demonstrate how PD can be applied to a policy-ready conservation planning problem. Our analysis bypasses named taxa, using genetic data directly to inform conservation decisions. We highlight areas that should be prioritised for ecological management, and also areas that would provide the greatest benefit if added to the multi-sector conservation estate. We provide a rigorous and effective approach to represent the spectrum of genetic and species diversity in conservation planning. This article is protected by copyright. All rights reserved
    Print ISSN: 1755-263X
    Electronic ISSN: 1755-263X
    Topics: Biology
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  • 28
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    Wiley-Blackwell
    Publication Date: 2018-01-17
    Description: Plant ecologists require spatial information on functional soil properties but are often faced with soil classifications that are not directly interpretable or useful for statistical models. Sand and clay content are important soil properties because they indicate soil water-holding capacity and nutrient content, yet these data are not available for much of the landscape. Remotely sensed soil radiometric data offer promise for developing statistical models of functional soil properties applicable over large areas. Here, we build models linking radiometric data for an area of 40,000 km 2 with soil physicochemical data collected over a period of 30 years and demonstrate a strong relationship between gamma radiometric potassium ( 40 K), thorium (²³²Th), and soil sand and clay content. Our models showed predictive performance of 43% with internal cross-validation (to held-out data) and ~30% for external validation to an independent test dataset. This work contributes to broader availability and uptake of remote sensing products for explaining patterns in plant distribution and performance across landscapes. Soil texture and chemistry significantly explained deviation in remote-sensed gamma-radiometric Th and K. Percent sand and clay particles in A Horizon were the most influential variables. Gamma-radiometric Th and and K, with environmental data, moderately predicted sand and clay %.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 29
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    Wiley-Blackwell
    Publication Date: 2018-01-17
    Description: Purines are metabolic building blocks essential for all living organisms on earth. De novo purine biosynthesis occurs in the brain and appears to play important roles in neural development. Phosphoribosyl formylglycinamidine synthase (FGAMS, also known as PFAS or FGARAT), a core enzyme involved in the de novo synthesis of purines, may play alternative roles in viral pathogenesis. To date, no thorough investigation of the endogenous expression and localization of de novo purine biosynthetic enzymes has been conducted in human neurons or in virally infected cells. In this study, we characterized expression of FGAMS using multiple neuronal models. In differentiated human SH-SY5Y neuroblastoma cells, primary rat hippocampal neurons, and in whole mouse brain sections, FGAMS immunoreactivity was distributed within the neuronal cytoplasm. FGAMS immunolabeling in vitro demonstrated extensive distribution throughout neuronal processes. To investigate potential changes in FGAMS expression and localization following viral infection, we infected cells with the human pathogen herpes simplex virus 1 (HSV-1). In infected fibroblasts, FGAMS immunolabeling shifted from a diffuse cytoplasmic location to a mainly perinuclear localization by 12 hours post infection. In contrast, in infected neurons, FGAMS localization showed no discernable changes in the localization of FGAMS immunoreactivity. There were no changes in total FGAMS protein levels in either cell type. Together, these data provide insight into potential purine biosynthetic mechanisms utilized within neurons during homeostasis as well as viral infection. This article is protected by copyright. All rights reserved.
    Print ISSN: 0022-3042
    Electronic ISSN: 1471-4159
    Topics: Medicine
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  • 30
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    Wiley-Blackwell
    Publication Date: 2018-01-17
    Description: Cellular prion protein (PrP C ) is widely expressed and displays a variety of well-described functions in the central nervous system (CNS). Mutations of the PRNP gene are known to promote genetic human spongiform encephalopathies, but the components of gain- or loss-of-function mutations to PrP C remain a matter for debate. Among the proteins described to interact with PrP C is stress inducible protein 1 (STI1), a co-chaperonin that is secreted from astrocytes and triggers neuroprotection and neuritogenesis through its interaction with PrP C . In this work, we evaluated the impact of different PrP C pathogenic point mutations on signaling pathways induced by the STI1-PrP C interaction. We found that some of the pathogenic mutations evaluated herein induce partial or total disruption of neuritogenesis and neuroprotection mediated by mitogen activated protein kinase (MAPK)/extracellular signal-regulated kinases 1 and 2 (ERK1/2) and protein kinase A (PKA) signaling triggered by STI1-PrP C engagement. A pathogenic mutant PrP C that lacked both neuroprotection and neuritogenesis activities fail to promote negative dominance upon wild-type PrP C . Also, a STI1-α7-nicotinic acetylcholine receptor-dependent cellular signaling was present in a PrP C mutant that maintained both neuroprotection and neuritogenesis activities similar to what has been previously observed by wild-type PrP C . These results point to a loss-of-function mechanism underlying the pathogenicity of PrP C mutations. This article is protected by copyright. All rights reserved.
    Print ISSN: 0022-3042
    Electronic ISSN: 1471-4159
    Topics: Medicine
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  • 31
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    Wiley-Blackwell
    Publication Date: 2018-01-17
    Description: Major depressive disorder is a common form of mental illness. Many brain regions are implicated in the pathophysiology and symptomatology of depression. Among key brain areas is the striatum that controls reward and mood and is involved in the development of core depression-like behavior in animal models of depression. While molecular mechanisms in this region underlying depression-related behavior are poorly understood, the glutamatergic input to the striatum is believed to play a role. In this study, we investigated changes in metabotropic glutamate (mGlu) receptor expression and signaling in the striatum of adult rats in response to prolonged (10-12 weeks) social isolation, a pre-validated animal paradigm modeling depression in adulthood. We found that mGlu5 receptor protein levels in the striatum were increased in rats that showed typical depression- and anxiety-like behavior after chronic social isolation. This increase in mGlu5 receptor expression was seen in both subdivisions of the striatum, the nucleus accumbens and caudate putamen. At subcellular and subsynaptic levels, mGlu5 receptor expression was elevated in surface membranes at synaptic sites. In striatal neurons, the mGlu5-associated phosphoinositide signaling pathway was augmented in its efficacy after prolonged social isolation. These data indicate that the mGlu5 receptor is a sensitive substrate of depression. Adulthood social isolation leads to the upregulation of mGlu5 receptor expression and function in striatal neurons. This article is protected by copyright. All rights reserved.
    Print ISSN: 0022-3042
    Electronic ISSN: 1471-4159
    Topics: Medicine
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  • 32
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    Wiley-Blackwell
    Publication Date: 2018-01-17
    Description: Characterization of the molecular signaling pathways underlying protein synthesis-dependent forms of synaptic plasticity, such as late long-term potentiation (L-LTP), can provide insights not only into memory expression/maintenance under physiological conditions but also potential mechanisms associated with the pathogenesis of memory disorders. Here, we report in mice that L-LTP failure induced by the mammalian (mechanistic) target of rapamycin complex 1 (mTORC1) inhibitor rapamycin is reversed by brain-specific genetic deletion of PKR-like ER kinase, PERK (PERK KO), a kinase for eukaryotic initiation factor 2α (eIF2α). In contrast, genetic removal of general control non-derepressible-2, GCN2 (GCN2 KO), another eIF2α kinase, or treatment of hippocampal slices with the PERK inhibitor GSK2606414, does not rescue rapamycin-induced L-LTP failure, suggesting mechanisms independent of eIF2α phosphorylation. Moreover, we demonstrate that phosphorylation of eukaryotic elongation factor 2 (eEF2) is significantly decreased in PERK KO mice but unaltered in GCN2 KO mice or slices treated with the PERK inhibitor. Reduction of eEF2 phosphorylation results in increased general protein synthesis, and thus could contribute to the mTORC1-independent L-LTP in PERK KO mice. We further performed experiments on mutant mice with genetic removal of eEF2K (eEF2K KO), the only known kinase for eEF2, and found that L-LTP in eEF2K KO mice is insensitive to rapamycin. These data, for the first time, connect reduction of PERK activity with the regulation of translation elongation in enabling L-LTP independent of mTORC1. Thus, our findings indicate previously unrecognized levels of complexity in the regulation of protein synthesis-dependent synaptic plasticity. This article is protected by copyright. All rights reserved.
    Print ISSN: 0022-3042
    Electronic ISSN: 1471-4159
    Topics: Medicine
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  • 33
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    Wiley-Blackwell
    Publication Date: 2018-01-19
    Description: Plant–soil feedbacks (PSFs) have gained attention for their potential role in explaining plant growth and invasion. While promising, most PSF research has measured plant monoculture growth on different soils in short-term, greenhouse experiments. Here, five soil types were conditioned by growing one native species, three non-native species, or a mixed plant community in different plots in a common-garden experiment. After 4 years, plants were removed and one native and one non-native plant community were planted into replicate plots of each soil type. After three additional years, the percentage cover of each of the three target species in each community was measured. These data were used to parameterize a plant community growth model. Model predictions were compared to native and non-native abundance on the landscape. Native community cover was lowest on soil conditioned by the dominant non-native, Centaurea diffusa , and non-native community cover was lowest on soil cultivated by the dominant native, Pseudoroegneria spicata . Consistent with plant growth on the landscape, the plant growth model predicted that the positive PSFs observed in the common-garden experiment would result in two distinct communities on the landscape: a native plant community on native soils and a non-native plant community on non-native soils. In contrast, when PSF effects were removed, the model predicted that non-native plants would dominate all soils, which was not consistent with plant growth on the landscape. Results provide an example where PSF effects were large enough to change the rank-order abundance of native and non-native plant communities and to explain plant distributions on the landscape. The positive PSFs that contributed to this effect reflected the ability of the two dominant plant species to suppress each other's growth. Results suggest that plant dominance, at least in this system, reflects the ability of a species to suppress the growth of dominant competitors through soil-mediated effects. A native and non-native plant community were grown on different soils during a seven-year plant–soil feedback experiment. Consistent with plant growth on the landscape, the native community grew poorly on soils cultivated by the dominant non-native plant, and the non-native community grew poorly on soils cultivated by the dominant native plant.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 34
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    Wiley-Blackwell
    Publication Date: 2018-01-19
    Description: Predators can affect prey through mechanisms other than predation; for example, redistributing resources could modify habitats favorably for other organisms. We examined Arctic fox ( Vulpes lagopus ) den use by lemmings, their primary prey, in winter during a year of low lemming densities. We found winter nests, which are built by lemmings under snow, on 69% of fox dens, whereas no control sites had nests. In August, dens had twice the vegetation cover and 50% greater nitrogen content in grass than controls, suggesting soil enrichment by foxes increased food quantity and quality for herbivores. Snow was ~4 times thicker in April on dens than controls, and 1.4 times thicker on dens with lemming nests than dens without, suggesting lemmings choose thicker snow for thermal insulation. Snow cover thickness was positively related to vegetation cover on dens, but not on control sites. Thus, Arctic foxes not only prey on lemmings but also engineer productive habitat that attracts lemmings. During winters with low lemming densities, when foxes often leave the denning area and predation risk is lower, fox dens may provide a refuge that could buffer the effects of deteriorating snow conditions with Arctic warming. This additional mechanism of predators interacting with their prey illustrates how ecosystem engineers potentially alter food web interactions and highlights the importance of integrating these bodies of theory in attempts to understand community dynamics.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 35
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    Wiley-Blackwell
    Publication Date: 2018-01-19
    Description: Plant functional traits research has revealed many interesting and important patterns among morphological, physiological, and life-history traits and the environment. These are exemplified in trade-offs between groups of traits such as those embodied in the leaf and wood economics spectra. Inferences from empirical studies are often constrained by the correlative nature of the analyses, availability of trait data, and a focus on easily measured traits. However, empirical studies have been fundamental to modeling endeavors aiming to enhance our understanding of how functional traits scale up to affect, for example, community dynamics and ecosystem productivity. Here, we take a complementary approach utilizing an individual-based model of tree growth and mortality (the allometrically constrained growth and carbon allocation [ACGCA] model) to investigate the theoretical trait space (TTS) of North American trees. The model includes 32 parameters representing allometric, physiological, and anatomical traits, some overlapping leaf and wood economics spectra traits. Using a Bayesian approach, we fit the ACGCA model to individual tree heights and diameters from the USFS Forest Inventory and Analysis (FIA) dataset, with further constraints by literature-based priors. Fitting the model to 1.3 million FIA records—aggregated across individuals, species, and sites—produced a posterior distribution of traits leading to realistic growth. We explored this multidimensional posterior distribution (the TTS) to evaluate trait–trait relationships emerging from the ACGCA model, and compare these against empirical patterns reported in the literature. Only three notable bivariate correlations, among 496 possible trait pairs, were contained in the TTS. However, stepwise regressions uncovered a complicated structure; only a subset of traits—related to photosynthesis (e.g., radiation-use efficiency and maintenance respiration)—exhibited strong multivariate trade-offs with each other, while half of the traits—mostly related to allometries and construction costs—varied independently of other traits. Interestingly, specific leaf area was related to several rarely measured root traits. The trade-offs contained in the TTS generally reflect mass-balance (related to carbon allocation) and engineering (mostly related to allometries) trade-offs represented in the ACGCA model and point to potentially important traits that are under-explored in field studies (e.g., root traits and branch senescence rates).
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 36
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    Wiley-Blackwell
    Publication Date: 2018-01-19
    Description: Forecast increases in the frequency, intensity, and duration of droughts with climate change may have extreme and extensive ecological consequences. There are currently hundreds of published, ongoing, and new drought experiments worldwide aimed to assess ecological sensitivity to drought and identify the mechanisms governing resistance and resilience. To date, the results from these experiments have varied widely, and thus, patterns of drought sensitivities and the underlying mechanisms have been difficult to discern. Here we examined 89 published drought experiments, along with their associated historical precipitation records to (1) identify where and how drought experiments have been imposed, (2) determine the extremity of drought treatments in the context of historical climate, and (3) assess the influence of ambient precipitation variability on the magnitude of drought experiments. In general, drought experiments were most common in water-limited ecosystems, such as grasslands, and were often short-term, as 80% were 1–4 yr in duration. When placed in a historical context, the majority of drought experiments imposed extreme drought, with 61% below the 5th, and 43% below the 1st percentile of the 50-yr annual precipitation distribution. We also determined that interannual precipitation variability had a large and potentially underappreciated effect on the magnitude of drought treatments due to the co-varying nature of control and drought precipitation inputs. Thus, detecting significant ecological effects in drought experiments is strongly influenced by the interaction between experimental drought magnitude, precipitation variability, and key ecological thresholds. The patterns that emerged from this study have important implications for the design and interpretation of drought experiments and also highlight critical gaps in our understanding of the ecological effects of drought.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 37
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    Wiley-Blackwell
    Publication Date: 2018-01-19
    Description: Species responses to climate change have been shown to vary in both direction and magnitude. Understanding these idiosyncratic responses is crucial if we are to predict extinction risk and set up efficient conservation strategies. The variations observed across species have been related to several species attributes including intrinsic traits such as physiological tolerances or life-history strategies but also to niche characteristics (e.g., niche breadth [NB], niche position [NP]). However, although previous studies have successfully linked species attributes to population dynamics or range shifts, few have considered synergistic effects to explain responses to climate variations. Here, we assessed whether five species attributes (fecundity, thermal safety margin, trophic position [TP], NB, and NP) explained interspecific differences in four parameters influencing population dynamics of 35 stream fish species at the French scale. We used Bayesian N-mixture models to estimate posterior distributions of the growth rate, the strength of density dependence, and the influence of both mean temperature and temperature variability on populations for each species. We then used phylogenetic generalized least squares (PGLS) models to investigate the influence of species attributes and their interactions on interspecific differences in each of the four parameter driving population dynamics. The percentage of variance explained by the PGLS models was relatively high (around 40% on average), indicating that species attributes are good predictors of species population dynamics. Furthermore, we showed that the influence of these single attributes was mediated by other attributes, especially NP and TP. Importantly, we found that models including interaction terms had greater support over simple additive models in explaining interspecific differences in population dynamics. Taken together, these results point to the importance of considering the interplay between species attributes in unraveling the mechanisms involved in population dynamics and understanding the vulnerability of species to global change.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 38
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    Wiley-Blackwell
    Publication Date: 2018-01-19
    Description: In semi-arid mountainous regions across the western United States, the distribution of upland aspen ( Populus tremuloides ) is often related to heterogeneous soil moisture subsidies resulting from redistributed snow. As temperatures increase, interactions between decreasing snowpack and future trends in the net primary productivity (NPP) of aspen forests remain uncertain. This study characterizes the importance of heterogeneously distributed snow water to aspen communities in the Reynolds Creek Critical Zone Observatory located in southwestern Idaho, USA. Net primary productivity of three aspen stands was simulated at sites spanning elevational and precipitation gradients using the biogeochemical process model Biome-BGC and precipitation data adjusted to account for drifting snow. Compared to a spatially homogeneous precipitation distribution, Biome-BGC simulations accounting for redistributed precipitation were in better agreement with previous simulations of snow accumulation and soil moisture field measurements. During drought years, simulations below the largest drifts that included wind-redistributed snow resulted in NPP values nearly 77% higher than simulations assuming uniform precipitation. However, during wet years (and at sites with higher total precipitation), increased effective precipitation resulting from drifting snow did not have a significant role in aspen productivity. In these cases, soil moisture was found to be non-limiting even in the absence of redistributed snow. Increased water availability from snow drifts often exceeded the storage capacity of the soil and contributed little to plant available water used later in the growing season.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 39
    Publication Date: 2018-01-19
    Description: Growth factor receptor tyrosine kinase (RTK) pathway activation is a key mechanism for mediating cancer growth, survival, and treatment resistance. Cognate ligands play crucial roles in autocrine or paracrine stimulation of these RTK pathways. Here, we show SEMA3C drives activation of multiple RTKs including EGFR, ErbB2, and MET in a cognate ligand-independent manner via Plexin B1. SEMA3C expression levels increase in castration-resistant prostate cancer (CRPC), where it functions to promote cancer cell growth and resistance to androgen receptor pathway inhibition. SEMA3C inhibition delays CRPC and enzalutamide-resistant progression. Plexin B1 sema domain-containing:Fc fusion proteins suppress RTK signaling and cell growth and inhibit CRPC progression of LNCaP xenografts post-castration in vivo . SEMA3C inhibition represents a novel therapeutic strategy for treatment of advanced prostate cancer. SEMA3C is a secreted autocrine factor that drives cancer growth and treatment resistance by transactivating multiple receptor tyrosine kinases via Plexin B1 in a cognate ligand-independent manner. Antagonizing SEMA3C signaling inhibits prostate cancer growth in vitro and in vivo .
    Print ISSN: 1757-4676
    Electronic ISSN: 1757-4684
    Topics: Medicine
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  • 40
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    Wiley-Blackwell
    Publication Date: 2018-01-19
    Description: Plant leaf phenology is typically observed either via ground-based visual observations on individuals or via remote sensing of land surface vegetation. To integrate phenological information from both data sources, collected at different spatial scales using different observational protocols, digital cameras were deployed spanning canopy areas with enough spatial resolution to identify temporal changes in individual deciduous tree species with continuous observations. Comparisons of phenology between camera photography and in situ observations have been reported in prior studies; however, it is still unclear that how these camera images relate to field observations at individual and species levels, and how the metrics from those images provide comparable species-specific phenological responses to environmental variation. We set a suite of digital time-lapse cameras to acquire continuous photographs of deciduous tree canopies and conducted ground-based visual observations in Connecticut, USA, from 2012 to 2014. Comparisons between image-derived dates and observed phenological dates showed that both green and red color indices could be matched to ground observations, and red color indices showed good performance in matching autumn phenology across our group of eight tree species that dominate the southern New England forests. Linear mixed-effects models were applied to investigate the relationships between climatic/weather conditions and the timing of peak and of intensity of red color in fall foliage for each species. Model results suggested that temperature, precipitation, drought stress in autumn, and heat stress in summer are all important factors to the timing of peak fall foliage color and that higher minimum temperatures (or lower cold degree-day accumulation) in the autumn are linked to higher intensity of red coloration at least in sugar maples. This study improves our understanding of temporal and spatial variation in the phenology of deciduous trees captured by digital cameras. As well, this provides insights into relating species-specific information on phenology from visual observations in the field to near-surface remote sensing and points to the need for further research on autumn phenology using the change in redness of tree canopies.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 41
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    Wiley-Blackwell
    Publication Date: 2018-01-19
    Description: Senescence is a highly variable process that comprises both age-dependent and state-dependent components and can be greatly affected by environmental conditions. However, few studies have quantified the magnitude of age-dependent and state-dependent senescence in key life-history traits across individuals inhabiting different spatially structured and seasonal environments. We used longitudinal data from wild female yellow-bellied marmots ( Marmota flaviventer ), living in two adjacent environments that differ in elevation and associated phenology, to quantify how age and individual state, measured as “time to death,” affect body mass senescence in different environments. Further, we quantified how patterns of senescence differed between two biologically distinct seasons, spring, and late summer. Body mass senescence had an age-dependent component, expressed as a decrease in mass in old age. Overall, estimated age-dependent senescence was greater in females living in the more favorable lower elevation environment, than in the harsher higher elevation environment, and greater in late summer than in spring. Body mass senescence also had a state-dependent component, captured by effects of time to death, but only in the more favorable lower elevation environment. In spring, body mass gradually decreased from 2 years before death, whereas in late summer, state-dependent effects were expressed as a terminal decrease in body mass in the last year of life. Contrary to expectations, we found that senescence was more likely to be observed under more favorable environmental conditions, rather than under harsher conditions. By further demonstrating that senescence patterns differ among seasons, our results imply that within-year temporal environmental variation must be considered alongside spatial environmental variation in order to characterize and understand the pattern and magnitude of senescence in wild populations. Few studies have quantified the magnitude of age-dependent and state-dependent senescence in key life-history traits across individuals inhabiting different spatially structured and seasonal environments. We show that age-dependent and state-dependent (i.e., time to death) effects on body mass co-occur in wild yellow-bellied marmots, and contrary to most previous studies, we found that senescence was more likely to be observed at lower rather than higher elevation. By further demonstrating that senescence patterns differ among seasons, our results imply that within-year temporal environmental variation must be considered alongside spatial environmental variation in order to characterize and understand the pattern and magnitude of senescence in natural populations.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 42
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    Wiley-Blackwell
    Publication Date: 2018-01-20
    Description: Ocean warming can modify the phytoplankton biomass on decadal scales. Significant increases in sea surface temperature (SST) and rainfall in the northwest of Australia over recent decades are attributed to climate change. Here, we used four biomarker proxies (TEX 86 index, long-chain n -alkanes, brassicasterol, and dinosterol) to reconstruct approximately 60-year variations of SST, terrestrial input, and diatom and dinoflagellate biomass in the coastal waters of the remote Kimberley region. The results showed that the most significant increases in SST and terrestrial input occurred since 1997, accompanied by an abrupt increase in diatom and dinoflagellate biomasses. Compared with the results before 1997, the average temperature during 1997–2011 increased approximately 1°C, rainfall increased 248.2 mm, brassicasterol and dinosterol contents increased 8.5 and 1.7 times. Principal component analysis indicated that the warming SST played a more important role in the phytoplankton increase than increased rainfall and river discharge. An abrupt increase in phytoplankton occurred since the 1990s, accompanied by significant increases in temperature and terrestrial input. Warming temperature played a more important role for the decadal phytoplankton increase than rainfall. Applicability of TEX86H biomarker proxy for SST off northwestern Australia was validated.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 43
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    Wiley-Blackwell
    Publication Date: 2018-01-20
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 44
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    Wiley-Blackwell
    Publication Date: 2018-01-20
    Description: Management and conservation strategies for endangered species require information on their temporal and spatial behavioral and habitat use relationships. We evaluated activity patterns and resource selection of black bears in northwestern Mexico. We surveyed 29 localities with 1450 camera traps stations from 2009 to 2013 in the states of Sonora and Chihuahua, Mexico. In each locality, we calculated the proportion of diurnal, nocturnal, and crepuscular activity through a kernel density estimator based on the time of independent photographic events, and we built a beta regression between diurnal density and annual temperature, seasonal rainfall (SR), human density, road density, daylight hours, season, and management type. To evaluate resource selection, we built a binomial logistic regression model incorporating Normalized Difference Vegetation Index (NDVI), mean and coefficient of variation of annual temperature, human population density (PD), terrain roughness, and season. Black bear activity was primarily diurnal with a bimodal tendency around sunrise and sunset. Diurnal activity (between sunrise and sunset) was positively influenced by daylight hours, SR, and private reserves and negatively influenced by anthropogenic factors. Resource selection was positively influenced by the coefficient of variation in temperature and NDVI and negatively associated with average annual temperature, PD, and terrain roughness. Activity patterns and resource use were similar to other regions in North America. However, temperature was one of the main factors influencing black bear activity and resource selection in our study areas and should be considered when developing management plans given projected increases in temperature expected under climate change scenarios. We present the first work of its kind for northwestern Mexico and considered it as an important component in future survey and management protocols for the species in the southern portion of its distribution.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 45
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    Wiley-Blackwell
    Publication Date: 2018-01-20
    Description: Identifying factors determining the performance of individuals is an essential part of resolving what drives population dynamics. For species undergoing ontogenetic shifts in resource and habitat use, this entails assessing individual performance in all habitats used. Whereas survival and growth of anadromous Atlantic salmon, Salmo salar L., in its juvenile, river habitat are known to depend on size-dependent foraging and food availability, individual performance of salmon in the growth habitat out at sea is commonly explained only by abiotic factors. Still, individuals undergo this habitat shift to grow large, suggesting performance should be food-dependent also in the growth habitat. Because fish communities are highly size-structured, the link between predators and their prey may depend on their respective body sizes. Here, we study whether the performance of Baltic Sea salmon in its growth habitat is food- and size-dependent, by combining extensive diet and body size data of Baltic salmon with spatially resolved monitoring data on abundance and size distribution of their main prey, herring, Clupea harengus L., and sprat, Sprattus sprattus L. We found that both the species and size composition of prey in the diet varied with salmon body size. By accounting for this size-dependent predation and the spatially varying size distribution of prey species, we could explain the variation in salmon diet composition among salmon individuals in different Baltic Sea basins and of different length. The proportion of sprat in diet of salmon was better explained by size-specific prey availability (SSP) than total prey biomass, especially for small salmon. Further, salmon body condition increased with SSP, whereas total prey biomass could not explain variation in the condition of salmon. These findings demonstrate that food- and size-dependent processes indeed can influence the performance of anadromous fish also in large marine systems. Thus, we argue that consideration of these processes, stretching across habitats, is important for understanding performance and dynamics of predatory fish in open aquatic systems, as well as for successful management of species such as Atlantic salmon.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 46
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    Wiley-Blackwell
    Publication Date: 2018-01-20
    Description: Detailed, regional climate projections, particularly for precipitation, are critical for many applications. Accurate precipitation downscaling in the United States Great Plains remains a great challenge for most Regional Climate Models, particularly for warm months. Most previous dynamic downscaling simulations significantly underestimate warm-season precipitation in the region. This study aims to achieve a better precipitation downscaling in the Great Plains with the Weather Research and Forecast (WRF) model. To this end, WRF simulations with different physics schemes and nudging strategies are first conducted for a representative warm season. Results show that different cumulus schemes lead to more pronounced difference in simulated precipitation than other tested physics schemes. Simply choosing different physics schemes is not enough to alleviate the dry bias over the southern Great Plains, which is related to an anticyclonic circulation anomaly over the central and western parts of continental U.S. in the simulations. Spectral nudging emerges as an effective solution for alleviating the precipitation bias. Spectral nudging ensures that large and synoptic-scale circulations are faithfully reproduced while still allowing WRF to develop small-scale dynamics, thus effectively suppressing the large-scale circulation anomaly in the downscaling. As a result, a better precipitation downscaling is achieved. With the carefully validated configurations, WRF downscaling is conducted for 1980-2015. The downscaling captures well the spatial distribution of monthly climatology precipitation and the monthly/yearly variability, showing improvement over at least two previously published precipitation downscaling studies. With the improved precipitation downscaling, a better hydrological simulation over the trans-state Oologah watershed is also achieved.
    Electronic ISSN: 1942-2466
    Topics: Geography , Geosciences
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  • 47
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    Wiley-Blackwell
    Publication Date: 2018-01-20
    Description: A decadal climate prediction system named as IAP-DecPreS was constructed in the Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences, based on a fully coupled model FGOALS-s2 and a newly developed initialization scheme, referred to as EnOI-IAU. In this paper, we introduce the design of the EnOI-IAU scheme, assess the accuracies of initialization integrations using the EnOI-IAU and preliminarily evaluate hindcast skill of the IAP-DecPreS. The EnOI-IAU scheme integrates two conventional assimilation approaches, ensemble optimal interpolation (EnOI) and incremental analysis update (IAU). The EnOI and IAU were applied to calculate analysis increments and incorporate them into the model, respectively. Three continuous initialization (INIT) runs were conducted for the period of 1950-2015, in which observational sea surface temperature (SST) from the HadISST1.1 and subsurface ocean temperature profiles from the EN4.1.1 dataset were assimilated. Then nine-member ten-year-long hindcast runs initiated from the INIT runs were conducted for each year in the period of 1960-2005. The accuracies of the INIT runs are evaluated from the following three aspects: upper-700m ocean temperature, temporal evolution of SST anomalies and dominant interdecadal variability modes, Pacific Decadal Oscillation (PDO) and Atlantic Multi-decadal Oscillation (AMO). Finally, preliminary evaluation of the ensemble mean of the hindcast runs suggests that the IAP-DecPreS has skill in the prediction of the PDO-related SST anomalies in the mid-latitude North Pacific and AMO-related SST anomalies in the tropical North Atlantic.
    Electronic ISSN: 1942-2466
    Topics: Geography , Geosciences
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  • 48
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    Wiley-Blackwell
    Publication Date: 2018-01-23
    Electronic ISSN: 2056-6646
    Topics: General, Interdisciplinary , Energy, Environment Protection, Nuclear Power Engineering
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  • 49
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    Wiley-Blackwell
    Publication Date: 2018-01-24
    Description: Since the mid-19th century, multiple introductions of Japanese sika deer ( Cervus nippon nippon ) and North American wapiti ( C. canadensis ) have taken place in the British Isles. While wapiti have generally been unsuccessful, sika have been very successful, especially in Scotland where they now overlap at least 40% of the range of native red deer ( C. elaphus ). Hybridization between these two species and red deer has been demonstrated in captivity and in the wild. Using a panel of 22 microsatellite loci that are highly diagnostic between red deer and sika, and moderately diagnostic between red deer and wapiti, we investigated the extent of introgression between these species in 2,943 deer sampled from around Scotland and from the English Lake District using the Bayesian clustering software STRUCTURE. We also used a diagnostic mitochondrial marker for red deer and sika. Our survey extends previous studies indicating little introgression of wapiti nuclear alleles into red deer, in particular in Northern Scotland, Kintyre, and the Lake District. We found a new area of extensive sika introgression in South Kintyre. In the North Highlands, we show for the first time geographically scattered evidence of past hybridization followed by extensive backcrossing, including one red-like individual with sika introgression, two sika-like individuals with red deer introgression, and six individuals that were apparently pure sika at the nuclear markers assessed but which carried red deer mitochondria. However, there has not been a collapse of assortative mating in this region. Similarly, in the English Lake District red deer, we found only traces of past sika introgression. No sika alleles were detected in the Central Highlands or the Hebridean red deer refugia. We make suggestions for management to prevent further spread of sika alleles into red deer and vice versa . We investigated the extent of introgression from introduced North American wapiti and Japanese sika into native red deer in 2,943 deer sampled from around Scotland and from the English Lake District. Wapiti introgression was very minor, but sika admixture was severe in two areas of Kintyre, Argyll, and in the North Highlands, there is a signature of past hybridization followed by extensive backcrossing to sika.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 50
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    Wiley-Blackwell
    Publication Date: 2018-01-23
    Description: Low clouds strongly impact the radiation budget of the climate system, but their simulation in most GCMs has remained a challenge, especially over the subtropical stratocumulus region. Assuming a Gaussian distribution for the subgrid-scale total water and liquid water potential temperature, a new statistical cloud scheme is proposed and tested in NCAR Community Atmospheric Model version 5 (CAM5). The subgrid-scale variance is diagnosed from the turbulent and shallow convective processes in CAM5. The approach is able to maintain the consistency between cloud fraction and cloud condensate and thus alleviates the adjustment needed in the default relative humidity based cloud fraction scheme. Short-term forecast simulations indicate that low cloud fraction and liquid water content, including their diurnal cycle, are improved due to a proper consideration of subgrid-scale variance over the southeastern Pacific Ocean region. Compared with the default cloud scheme, the new approach produced the mean climate reasonably well with improved shortwave cloud forcing (SWCF) due to more reasonable low cloud fraction and liquid water path over regions with predominant low clouds. Meanwhile, the SWCF bias over the tropical land regions is also alleviated. Furthermore, the simulated marine boundary layer clouds with the new approach extend further offshore and agree better with observations. The new approach is able to obtain the top of atmosphere (TOA) radiation balance with a slightly alleviated double ITCZ problem in preliminary coupled simulations. This study implies that a close coupling of cloud processes with other subgrid-scale physical processes is a promising approach to improve cloud simulations.
    Electronic ISSN: 1942-2466
    Topics: Geography , Geosciences
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  • 51
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    Wiley-Blackwell
    Publication Date: 2018-01-23
    Description: A recent study revealed that corticotropin-releasing hormone (CRH) in the cerebral cortex (CTX) plays a regulatory role in emotional behaviors in rodents. Given the functional interaction between brain-derived neurotrophic factor (BDNF) and the CRH-signaling pathway in the hypothalamic-pituitary-adrenal (HPA) axis, we hypothesized that BDNF may regulate gene expression of CRH and its related molecules in the CTX. Findings of real-time quantitative PCR (RT-qPCR) indicated that stimulation of cultured rat cortical neurons with BDNF led to marked elevations in the mRNA levels of CRH and CRH-binding protein (CRH-BP). The BDNF-induced upregulation of CRH-BP mRNA was attenuated by inhibitors of tyrosine receptor kinase (Trk) and MEK, but not by an inhibitor for PI3K and PLCγ. The upregulation was partially blocked by an inhibitor of lysine-specific demethylase (KDM) 6B. Fluorescent imaging identified the vesicular pattern of pH-sensitive green fluorescent protein-fused CRH-BP (CRH-BP-pHluorin), which co-localized with mCherry-tagged BDNF in cortical neurons. In addition, live-cell imaging detected drastic increases of pHluorin fluorescence in neurites upon membrane depolarization. Finally, we confirmed that tetrodotoxin (TTX) partially attenuated the BDNF-induced upregulation of CRH-BP mRNA, but not that of the protein. These observations indicate the following: In cortical neurons, BDNF led to gene expression of CRH-BP and CRH. TrkB, MEK, presumably ERK, and KDM6B are involved in the BDNF-induced gene expression of CRH-BP, and BDNF is able to induce the upregulation in a neuronal activity-independent manner. It is suggested that CRH-BP is stored into BDNF-containing secretory granules in cortical neurons, and is secreted in response to membrane depolarization. This article is protected by copyright. All rights reserved.
    Print ISSN: 0022-3042
    Electronic ISSN: 1471-4159
    Topics: Medicine
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  • 52
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    Wiley-Blackwell
    Publication Date: 2018-01-24
    Description: Disentangling the different processes structuring ecological communities is a long-standing challenge. In species-rich ecosystems, most emphasis has so far been given to environmental filtering and competition processes, while facilitative interactions between species remain insufficiently studied. Here, we propose an analysis framework that not only allows for identifying pairs of facilitating and facilitated species, but also estimates the strength of facilitation and its variation along environmental gradients. Our framework combines the analysis of both co-occurrence and co-abundance patterns using a moving window approach along environmental gradients to control for potentially confounding effects of environmental filtering in the co-abundance analysis. We first validate our new approach against community assembly simulations, and exemplify its potential on a large 1,134 plant community plots dataset. Our results generally show that facilitation intensity was strongest under cold stress, whereas the proportion of facilitating and facilitated species was higher under drought stress. Moreover, the functional distance between individual facilitated species and their facilitating species significantly changed along the temperature–moisture gradient, and seemed to influence facilitation intensity, although no general positive or general negative trend was discernible among species. The main advantages of our robust framework are as follows: It enables detecting facilitating and facilitated species in species-rich systems, and it allows identifying the directionality and intensity of facilitation in species pairs as well as its variation across long environmental gradients. It thus opens numerous opportunities for incorporating functional (and phylogenetic) information in the analysis of facilitation patterns. Our case study indicated high complexity in facilitative interactions across the stress gradient and revealed new evidence that facilitation, similarly to competition, can operate between functionally similar and dissimilar species. Extending the analyses to other taxa and ecosystems will foster our understanding how complex interspecific interactions promote biodiversity. Identifying facilitative interactions in species-rich systems is a long-standing challenge. Here, we propose a simple analysis framework that allows identifying pairs of facilitating and facilitated species, estimating the strength of their interaction and its variation along environmental gradients. We validate our approach against community assembly simulations and exemplify its potential on a large plant community dataset. Our results show that although facilitation intensity is strongest under cold stress, the proportion of facilitating and facilitated species is higher under drought stress.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 53
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    Wiley-Blackwell
    Publication Date: 2018-01-24
    Description: The blood vasculature is an organ pervading all other organs (almost). During vascular development, cell–cell signaling by extracellular ligands and cell surface receptors ensure that new vessels sprout into non-vascularized regions and simultaneously acquire organ-specific specializations and adaptations that match the local physiological needs. The vessels thereby specialize in their permeability, molecular transport between blood and tissue, and ability to regulate blood flow on demand. Over the past decades, we have learnt about the generic cell–cell signaling mechanisms governing angiogenic sprouting, mural cell recruitment, and vascular remodeling, and we have obtained the first insights into signals that induce and maintain vascular organotypicity. However, intra-organ vascular diversity and arterio-venous hierarchies complicate the molecular characterization of the vasculature's cellular building blocks. Single-cell RNA sequencing provides a way forward, as it allows elucidation at a genome-wide and quantitative level of the transcriptional diversity occurring within the same cell types at different anatomical positions and levels of arterio-venous hierarchy in the organs. In this Louis-Jeantet Prize Winner: Commentary , I give a brief overview of vascular development and how recent advances in the field pave the way for more systematic efforts to explore vascular functions in health and disease. The 2017 Louis-Jeantet Prize for Medicine winner Christer Betsholtz provides an interesting account of his work in vascular biology, in particular the characterisation of pericytes and their role in vascular development and permeability.
    Print ISSN: 1757-4676
    Electronic ISSN: 1757-4684
    Topics: Medicine
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  • 54
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    Wiley-Blackwell
    Publication Date: 2018-01-25
    Description: Key developments have been made to the NCAR Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X). Among them the most important are the self-consistent solution of global electrodynamics, and transport of O + in the F-region. Other ionosphere developments include time-dependent solution of electron/ion temperatures, metastable O + chemistry, and high-cadence solar EUV capability. Additional developments of the thermospheric components are improvements to the momentum and energy equation solvers to account for variable mean molecular mass and specific heat, a new divergence damping scheme, and cooling by O( 3 P) fine structure. Simulations using this new version of WACCM-X (2.0) have been carried out for solar maximum and minimum conditions. Thermospheric composition, density, and temperatures are in general agreement with measurements and empirical models, including the equatorial mass density anomaly and the midnight density maximum. The amplitudes and seasonal variations of atmospheric tides in the mesosphere and lower thermosphere are in good agreement with observations. Although global mean thermospheric densities are comparable with observations of the annual variation, they lack a clear semi-annual variation. In the ionosphere, the low-latitude E×B drifts agree well with observations in their magnitudes, local time dependence, seasonal, and solar activity variations. The pre-reversal enhancement in the equatorial region, which is associated with ionospheric irregularities, displays patterns of longitudinal and seasonal variation that are similar to observations. Ionospheric density from the model simulations reproduces the equatorial ionosphere anomaly structures, and is in general agreement with observations. The model simulations also capture important ionospheric features during storms.
    Electronic ISSN: 1942-2466
    Topics: Geography , Geosciences
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  • 55
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    Wiley-Blackwell
    Publication Date: 2018-01-26
    Description: Species distribution modeling (SDM) is an essential method in ecology and conservation. SDMs are often calibrated within one country's borders, typically along a limited environmental gradient with biased and incomplete data, making the quality of these models questionable. In this study, we evaluated how adequate are national presence-only data for calibrating regional SDMs. We trained SDMs for Egyptian bat species at two different scales: only within Egypt and at a species-specific global extent. We used two modeling algorithms: Maxent and elastic net, both under the point-process modeling framework. For each modeling algorithm, we measured the congruence of the predictions of global and regional models for Egypt, assuming that the lower the congruence, the lower the appropriateness of the Egyptian dataset to describe the species' niche. We inspected the effect of incorporating predictions from global models as additional predictor (“prior”) to regional models, and quantified the improvement in terms of AUC and the congruence between regional models run with and without priors. Moreover, we analyzed predictive performance improvements after correction for sampling bias at both scales. On average, predictions from global and regional models in Egypt only weakly concur. Collectively, the use of priors did not lead to much improvement: similar AUC and high congruence between regional models calibrated with and without priors. Correction for sampling bias led to higher model performance, whatever prior used, making the use of priors less pronounced. Under biased and incomplete sampling, the use of global bats data did not improve regional model performance. Without enough bias-free regional data, we cannot objectively identify the actual improvement of regional models after incorporating information from the global niche. However, we still believe in great potential for global model predictions to guide future surveys and improve regional sampling in data-poor regions. Species distribution models are often calibrated within one country's borders, typically along a limited environmental gradient with biased and incomplete data, making the quality of these models questionable. In this study, we evaluated how adequate are national presence-only data for calibrating regional SDMs and how much improvement occurs after incorporating information from global models as additional predictor (priors). Correction for sampling bias led to higher model performance, whatever prior used, making the use of priors less pronounced. Under biased and incomplete sampling, the use of global data did not improve regional model performance. However, we still believe in great potential for global model predictions to guide future surveys and improve regional sampling in data-poor regions.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 56
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    Wiley-Blackwell
    Publication Date: 2018-01-27
    Description: Almost all large rivers worldwide are fragmented by dams, and their impacts have been modeled using the serial discontinuity concept (SDC), a series of predictions regarding responses of key biotic and abiotic variables. We evaluated the effects of damming on anuran communities along a 245-km river corridor by conducting repeated, time-constrained anuran calling surveys at 42 locations along the Broad and Pacolet Rivers in South Carolina, USA. Using a hierarchical Bayesian analysis, we test the biodiversity prediction of the SDC (modified for floodplain rivers) by evaluating anuran occupancy and species diversity relative to dams and degree of urbanized land use. The mean response of the anuran community indicated that occupancy and species richness were maximized when sites were farther downstream from dams. Sites at the farthest distances downstream of dams (47.5 km) had an estimated ~3 more species than those just below dams. Similarly, species-specific occupancy estimates showed a trend of higher occupancy downstream from dams. Therefore, using empirical estimation within the context of a 245-km river riparian landscape, our study supports SDC predictions for a meandering river. We demonstrate that with increasing distance downstream from dams, riparian anuran communities have higher species richness. Reduced species richness immediately downstream of dams is likely driven by alterations in flow regime that reduce or eliminate flows which sustain riparian wetlands that serve as anuran breeding habitat. Therefore, to maintain anuran biodiversity, we suggest that flow regulation should be managed to ensure water releases inundate riparian wetlands during amphibian breeding seasons and aseasonal releases, which can displace adults, larvae, and eggs, are avoided. These outcomes could be achieved by emulating pre-dam seasonal discharge data, mirroring discharge of an undammed tributary within the focal watershed, or by basing real-time flow releases on current environmental conditions. We evaluated the effects of damming on anuran communities along a 245 km river corridor. We test the biodiversity prediction of the Serial Discontinuity Concept by evaluating anuran spatial distributions relative to dams. Our study supports predictions of the Serial Discontinuity Concept and our results indicate that with increasing distance downstream from dams, riparian anuran communities have higher species richness. Photo by Mitchell Pruitt.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 57
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    Wiley-Blackwell
    Publication Date: 2018-01-27
    Description: This Editorial highlights an article in the current issue by Tapia-Rojas and Inestrosa suggesting that attenuation of Wnt signalling may be a triggering factor for the pathogenesis of Alzheimer disease (AD) in the J20 mouse model of AD. Their study utilises Wnt signalling inhibitors that operate at different points in the signalling pathway. The molecular changes of several key Wnt signaling components are examined, along with a thorough analysis of both the amyloid and tau based pathologies in the mouse brain. Studies focusing on inhibition of Wnt signalling in AD mice have the potential to provide much needed information regarding the pathological mechanisms by which attenuated Wnt signalling impacts on AD. This is an Editorial on ‘Wnt signaling loss accelerates the appearance of neuropathological hallmarks of Alzheimer's disease in J20-APP transgenic and wild-type mice’ in the current issue of the Journal of Neurochemistry . In the highlighted paper, Tapia-Rojas and Inestrosa blocked Wnt signalling at three points as indicated by the red crosses. The agents used to attenuate signalling were administered to J20 Alzheimer's disease (AD) mice and wild-type mice. The Wnt inhibitor promoted the AD phenotype in J20 mice and led to changes that are relevant to AD in the wild-type mice.
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  • 58
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    Wiley-Blackwell
    Publication Date: 2018-01-28
    Description: Hybridization between wild species and their domestic congeners is considered a major threat for wildlife conservation. Genetic integrity of the European wildcat, for instance, is a concern as they are outnumbered by domestic cats by several orders of magnitude throughout its range. We genotyped 1,071 individual wildcat samples obtained from hair traps and roadkills collected across the highly fragmented forests of western Central Europe, in Germany and Luxembourg, to assess domestic cat introgression in wildcats in human-dominated landscapes. Analyses using a panel of 75 autosomal SNPs suggested a low hybridization rate, with 3.5% of wildcat individuals being categorized as F1, F2, or backcrosses to either parental taxon. We report that results based on a set of SNPs were more consistent than on a set of 14 microsatellite markers, showed higher accuracy to detect hybrids and their class in simulation analyses, and were less affected by underlying population structure. Our results strongly suggest that very high hybridization rates previously reported for Central Europe may be partly due to inadequate choice of markers and/or sampling design. Our study documents that an adequately selected SNP panel for hybrid detection may be used as an alternative to commonly applied microsatellite markers, including studies relying on noninvasively collected samples. In addition, our finding of overall low hybridization rates in Central European wildcats provides an example of successful wildlife coexistence in human-dominated, fragmented landscapes. ”We assess hyribization between wildcats and domestic cats in Germany and Luxembourg, and offer an explanation for greatly differing previous estimates, contrasting with those reported in our and other studies. We use microsatellites, SNPs and control region mtDNA sequences, as well as different sampling strategies (hair trapping and roadkill specimen collection) of 1.071 individuals. Our results showed that study setup concerning the choice of markers and sampling affect inferred hybridization rates. Our study documents very low hybridization rates between a wild and a domestic taxon despite close coexistence and widespread anthropogenic disturbance.”
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 59
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    Wiley-Blackwell
    Publication Date: 2018-01-28
    Description: Sphingosine 1-phosphate receptors (S1PR) are G protein-coupled and compose a family with five subtypes, S1P1R – S1P5R. The drug Gilenya ® (Fingolimod; FTY720) targets S1PRs and was the first oral therapy for patients with relapsing-remitting multiple sclerosis (MS). The phosphorylated form of FTY720 (pFTY720) binds S1PRs causing initial agonism, then subsequent receptor internalisation and functional antagonism. Internalisation of S1P1R attenuates sphingosine 1-phosphate (S1P)-mediated egress of lymphocytes from lymph nodes, limiting aberrant immune function in MS. pFTY720 also exerts direct actions on neurons and glial cells which express S1PRs. In the current study, we investigated the regulation of pro-inflammatory chemokine release by S1PRs in enriched astrocytes and microglial cultures. Astrocytes and microglia were stimulated with lipopolysaccharide (LPS) and increases in C-X-C motif chemokine 5 (CXCL5), also known as LIX lipopolysaccharide-induced CXC chemokine), expression were quantified. Results showed pFTY720 attenuated LPS-induced CXCL5 (LIX) protein release from astrocytes, as did the S1P1R selective agonist, SEW2871. In addition, pFTY720 blocked messenger ribonucleic acid (mRNA) transcription of the chemokines, 1) CXCL5/LIX, 2) C-X-C motif chemokine 10 (CXCL10) also known as interferon gamma-induced protein 10 (IP10), and 3) chemokine (C-C motif) ligand 2 (CCL2) also known as monocyte chemoattractant protein 1 (MCP1). Interestingly, inhibition of sphingosine kinase (SphK) attenuated LPS-induced increases in mRNA levels of all three chemokines, suggesting that LPS-TLR4 (Toll-like receptor 4) signalling may enhance chemokine expression via S1P-S1PR transactivation. Lastly, these observations were not limited to astrocytes since we also found that pFTY720 attenuated LPS-induced release of CXCL5 from microglia. These data highlight a role for S1PR signalling in regulating the levels of chemokines in glial cells and support the notion that pFTY720 efficacy in multiple sclerosis may involve the direct modulation of astrocytes and microglia. This article is protected by copyright. All rights reserved.
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  • 60
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    Wiley-Blackwell
    Publication Date: 2018-01-29
    Description: Myelin, an insulating membrane that enables rapid action potential propagation, is an essential component of an efficient, functional vertebrate nervous system. Oligodendrocytes, the myelinating glia of the central nervous system (CNS), produce myelin throughout the CNS, which requires continuous proliferation, migration and differentiation of oligodendrocyte progenitor cells (OPC). Because myelination is essential for efficient neurotransmission, researchers hypothesize that neuronal signals may regulate the cascade of events necessary for this process. The ability of oligodendrocytes and OPCs to detect and respond to neuronal activity is becoming increasingly appreciated, although the specific signals involved are still a matter of debate. Recent evidence from multiple studies points to purinergic signaling as a potential regulator of oligodendrocyte development and differentiation. Adenosine triphosphate (ATP) and its derivatives are potent signaling ligands with receptors expressed on many populations of cells in the nervous system, including cells of the oligodendrocyte lineage. Release of ATP into the extracellular space can initiate a multitude of signaling events, and these downstream signals are specific to the particular purinergic receptor (or receptors) expressed, and whether enzymes are present to hydrolyze ATP to its derivatives adenosine diphosphate (ADP) and adenosine, each of which can activate their own unique downstream signaling cascades. This review will introduce purinergic signaling in the CNS and discuss evidence for its effects on oligodendrocyte proliferation, differentiation and myelination. We will review sources of extracellular purines in the nervous system and how changes in purinergic receptor expression may be coupled to oligodendrocyte differentiation. We will also briefly discuss purinergic signaling in injury and diseases of the CNS. This article is protected by copyright. All rights reserved.
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  • 61
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    Wiley-Blackwell
    Publication Date: 2018-01-28
    Description: s Cannibalism is induced in larval-stage populations of the Hokkaido salamander, Hynobius retardatus , under the control of a cannibalism reaction norm. Here, I examined phenotypic expression under the cannibalism reaction norm, and how the induction of a cannibalistic morph under the norm leads to populational morphological diversification. I conducted a set of experiments in which density was manipulated to be either low or high. In the high-density treatment, the populations become dimorphic with some individuals developing into the cannibal morph type. I performed an exploratory analysis based on geometric morphometrics and showed that shape characteristics differed between not only cannibal and noncannibal morph types in the high-density treatment but also between those morph types and the solitary morph type in the low-density treatment. Size and shape of cannibal and noncannibal individuals were found to be located at either end of a continuum of expression following a unique size–shape integration rule that was different from the rule governing the size and shape variations of the solitary morph type. This result implies that the high-density-driven inducible morphology of an individual is governed by a common integration rule during the development of dimorphism under the control of the cannibalism reaction norm. Phenotypic expression under the cannibalism reaction norm is driven not only by population density but also by social interactions among the members of a population: variation in the populational expression of dimorphism is associated with contingent social interaction events among population members. The induced cannibalistic morph thus reflects not only by contest-type exploitative competition but also interference competition. I clarified how the cannibalism induction reaction norm of the Hokkaido salamander Hynobius retardatus makes populational morphological diversification. The reaction norm is driven not only by the density of conspecifics but also by the contingent social interactions with the population.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 62
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    Wiley-Blackwell
    Publication Date: 2018-01-29
    Description: The KwaZulu-Natal yellowfish ( Labeobarbus natalensis ) is an abundant cyprinid, endemic to KwaZulu-Natal Province, South Africa. In this study, we developed a single-nucleotide polymorphism (SNP) dataset from double-digest restriction site-associated DNA (ddRAD) sequencing of samples across the distribution. We addressed several hidden challenges, primarily focusing on proper filtering of RAD data and selecting optimal parameters for data processing in polyploid lineages. We used the resulting high-quality SNP dataset to investigate the population genetic structure of L. natalensis . A small number of mitochondrial markers present in these data had disproportionate influence on the recovered genetic structure. The presence of singleton SNPs also confounded genetic structure. We found a well-supported division into northern and southern lineages, with further subdivision into five populations, one of which reflects north–south admixture. Approximate Bayesian Computation scenario testing supported a scenario where an ancestral population diverged into northern and southern lineages, which then diverged to yield the current five populations. All river systems showed similar levels of genetic diversity, which appears unrelated to drainage system size. Nucleotide diversity was highest in the smallest river system, the Mbokodweni, which, together with adjacent small coastal systems, should be considered as a key catchment for conservation. We present the development of a high-quality SNP panel from double-digest restriction site-associated DNA (ddRAD) sequencing of a hexaploid freshwater fish, Labeobarbus natalensis . We use the SNP dataset to investigate the phylogeography of this species across the distribution and delimit it into five major populations grouped by drainage system. We encountered a number of unexpected challenges when working with this dataset, emphasizing the need for proper filtering of RAD datasets and optimization of parameter selection.
    Electronic ISSN: 2045-7758
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  • 63
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    Wiley-Blackwell
    Publication Date: 2018-01-31
    Description: Despite billions of dollars invested, “getting to scale” remains a fundamental challenge for conservation donors and practitioners. Occasionally, however, a conservation intervention will “go viral,” with rapid, widespread adoption that transforms the relationship between people and nature across large areas. The factors that shape rates and patterns of conservation interventions remain unclear, puzzling scientists and hindering evidence-based policymaking. Diffusion of innovation theory – the study of the how and why innovations are adopted, and the rates and patterns of adoption – provides a novel lens for examining rates and patterns in the establishment of conservation interventions. Case studies from Tanzania and the Pacific illustrate that characteristics of the innovation, of the adopters, and of the social-ecological context shape spatial and temporal dynamics in the diffusion of community-centered conservation interventions. Differential trends in adoption mirrored the relative advantage of interventions to local villagers and villager access to external technical assistance. Theories of innovation diffusion highlight new arenas for conservation research and provide critical insights for conservation policy and practice, suggesting the potential to empower donors and practitioners with the ability to catalyze conservation at scale – and to do so at less cost and with longer-lasting impacts. This article is protected by copyright. All rights reserved
    Print ISSN: 1755-263X
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  • 64
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    Wiley-Blackwell
    Publication Date: 2018-02-01
    Description: A species has a post-reproductive stage if, like humans, a female entering the adult population can expect to live a substantial proportion of their life after their last reproductive event. However, it is conceptually and statistically challenging to distinguish these true post-reproductive stages from the usual processes of senescence, which can result in females occasionally surviving past their last reproductive event. Hence, despite considerable interest, the taxonomic prevalence of post-reproductive stages remains unclear and debated. In this study we use life tables constructed from published data on wild populations of mammals, and statistical measures of post-reproductive lifespans, to distinguish true post-reproductive stages from artefacts of senescence and demography in 52 species. We find post-reproductive stages are rare in mammals and are limited to humans and a few species of toothed whales. By resolving this long-standing debate, we hope to provide clarity for researchers in the field of evolutionary biology and a solid foundation for further studies investigating the evolution and adaptive significance of this unusual life history trait. Despite considerable interest, the taxonomic prevalence of extended human menopause-like postreproductive stages in mammals remains unclear and debated. In this article, we show that postreproductive lifespans are limited to humans and a couple of species of toothed whale.
    Electronic ISSN: 2045-7758
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  • 65
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    Wiley-Blackwell
    Publication Date: 2018-02-01
    Description: The ideal free distribution (IFD) requires that individuals can accurately perceive density-dependent habitat quality, while failure to discern quality differences below a given perception threshold results in distributions approaching spatial uniformity. Here, we investigate the role of population growth in restoring a nonideal population to the IFD. We place a simple model of discrete patch choice under limits to the resolution by which patch quality is perceived and include population growth driven by that underlying quality. Our model follows the population's distribution through both breeding and dispersal seasons when perception limits differ in their likely influence. We demonstrate that populations of perception limited movers can approximate an IFD provided sufficient population growth; however, the emergent IFD would be temporally inconstant and correspond to reproductive events. The time to emergence of the IFD during breeding is shorter under exponential growth than under logistic growth. The IFD during early colonization of a community persists longer when more patches are available to individuals. As the population matures and dispersal becomes increasingly random, there is an oscillation in the observance of IFD, with peaks most closely approximating the IFD occurring immediately after reproductive events, and higher reproductive rates producing distributions closer to the IFD. The Ideal Free Distribution (IFD) is the theoretical underpinning of numerous ecological models, yet multiple conditions can contribute to deviation from IFD. We show that inclusion of population dynamics can overcome non-ideal behavior to promote the emergence of IFD. We discuss how these findings influence numerous ecological processes and our use of distribution models, and provide suggestions on how to improve detection and study of IFD.
    Electronic ISSN: 2045-7758
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  • 66
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    Wiley-Blackwell
    Publication Date: 2018-02-02
    Description: Understanding introduction routes for wildlife pathogens is vital for the development of threat abatement plans. The chytrid fungus Batrachochytrium salamandrivorans (Bsal) has recently emerged in Europe, where it is considered to be a serious threat for urodelan conservation. If the highly diverse Chinese urodelans were to constitute a Bsal reservoir, then the significant international trade in these species may vector Bsal into naïve urodelan communities. Here, we analyzed a total of 1,143 samples, representing 36 Chinese salamander species from 51 localities across southern China for the presence of Bsal. We found Bsal was present across a wide taxonomic, geographical, and environmental range. In particular, Bsal DNA was detected in 33 samples from the genera Cynops , Pachytriton , Paramesotriton , Tylototriton , and Andrias , including the heavily traded species Paramesotriton hongkongensis and Cynops orientalis . The true Bsal prevalence across our data set was estimated between 2% and 4%, with a maximum of 50% in a population of P. hongkongensis . Even at this overall relatively low Bsal prevalence, the exportation of millions of animals renders Bsal introduction in naïve, importing countries a near certainty, which calls for the urgent implementation of proper biosecurity in the international wildlife trade.
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  • 67
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    Wiley-Blackwell
    Publication Date: 2018-02-02
    Description: Oceanic islands are vulnerable ecosystems and their flora has been under pressure since the arrival of the first humans. Human activities and both deliberately and inadvertently introduced biota have had and continue to have a severe impact on island endemic plants. The number of alien plants has increased nearly linearly on many islands, perhaps resulting in extinction-based saturation of island floras. Here, we provide evidence for such a scenario in Alejandro Selkirk, Robinson Crusoe Islands (Archipelago Juan Fernández, Chile). We compared species richness and species composition of historical vegetation samples from 1917 with recent ones from 2011. Changes in species’ relative occurrence frequency were related to their taxonomic affiliation, dispersal mode, distribution status, and humidity and temperature preferences. While total species richness of vascular plants remained relatively similar, species composition changed significantly. Plants endemic to the Robinson Crusoe Islands declined, exotic species increased substantially within the period of ca. 100 years. Further, the relative occurrence frequency of plants with preferences for very warm and humid climate decreased, while the opposite was found for plants preferring drier and colder environments. Potential drivers responsible for this dramatic shift in the vegetation within only one century might have been the large goat population affecting especially small populations of endemic plants and climatic changes. Taking into account a substantial extinction debt, we expect further shifts in the vegetation of this small oceanic island toward alien plants. This would have significant negative consequences on global biodiversity, considering that island floras contribute substantially to global plant species richness due to their high proportion of endemics. On the island Alejandro Selkirk (Robinson Crusoe Islands), plant species composition changed significantly although species richness remained similar. Endemic plants declined, and exotic species increased substantially within the period of ca. 100 years.
    Electronic ISSN: 2045-7758
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  • 68
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    Wiley-Blackwell
    Publication Date: 2018-02-02
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 69
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    Wiley-Blackwell
    Publication Date: 2018-02-02
    Description: Gene flow has historically been thought to constrain local adaptation; yet, recent research suggests that populations can diverge despite exchanging genes. Here I use a common garden experiment to assess the combined effects of gene flow and natural selection on morphological variation of 16 wood frog ( Rana sylvatica ) populations, a species known to experience divergent selection pressures in open- and closed-canopy ponds across relatively small geographic scales. Wood frog tadpoles from different ponds showed significant morphological variation associated with canopy type with a trade-off between tail length and body depth consistent with previous research. In contrast, neutral genetic differentiation of nine microsatellite loci as measured by Jost's D was not associated with canopy type, indicating no pattern of isolation by environment. Genetic structure analyses indicated some substructure across the 16 ponds ( K  =   4); however, three out of four assigned clusters included both open- and closed-canopy ponds. Together, these results suggest that morphological divergence among these wood frog populations is occurring despite gene flow and that selection within these environments is strong. Furthermore, morphological variation among ponds differed across two sampling periods during larval development, demonstrating the importance of evaluating phenotypic divergence over multiple time periods and at a time relevant to the processes being studied. In this article, I investigate the role of gene flow and environment on morphological variation across larval wood frog populations using a common garden experiment. The results indicate that wood frog larvae show fine-scale morphological variation across ponds consistent with environmental differences and regardless of high levels of gene flow.
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  • 70
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    Wiley-Blackwell
    Publication Date: 2018-02-02
    Description: Vultures provide an essential ecosystem service through removal of carrion, but globally, many populations are collapsing and several species are threatened with extinction. Widespread declines in vulture populations could increase the availability of carrion to other organisms, but the ways facultative scavengers might respond to this increase have not been thoroughly explored. We aimed to determine whether facultative scavengers increase carrion consumption in the absence of vulture competition and whether they are capable of functionally replacing vultures in the removal of carrion biomass from the landscape. We experimentally excluded 65 rabbit carcasses from vultures during daylight hours and placed an additional 65 carcasses that were accessible to vultures in forested habitat in South Carolina, USA during summer (June–August). We used motion-activated cameras to compare carrion use by facultative scavenging species between the experimental and control carcasses. Scavenging by facultative scavengers did not increase in the absence of competition with vultures. We found no difference in scavenger presence between control carcasses and those from which vultures were excluded. Eighty percent of carcasses from which vultures were excluded were not scavenged by vertebrates, compared to 5% of carcasses that were accessible to vultures. At the end of the 7-day trials, there was a 10.1-fold increase in the number of experimental carcasses that were not fully scavenged compared to controls. Facultative scavengers did not functionally replace vultures during summer in our study. This finding may have been influenced by the time of the year in which the study took place, the duration of the trials, and the spacing of carcass sites. Our results suggest that under the warm and humid conditions of our study, facultative scavengers would not compensate for loss of vultures. Carcasses would persist longer in the environment and consumption of carrion would likely shift from vertebrates to decomposers. Such changes could have substantial implications for disease transmission, nutrient cycling, and ecosystem functioning. We excluded vultures from carcasses to measure the response of scavenging mammals. Mammals did not increase carrion consumption in the absence of vulture competition. Carcasses persisted longer when vultures were excluded, indicating that mammals would not functionally replace vultures as scavengers under these conditions.
    Electronic ISSN: 2045-7758
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  • 71
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    Wiley-Blackwell
    Publication Date: 2018-02-02
    Description: Insects are important but overlooked components of forest ecosystems in New Zealand. For many insect species, information on foraging patterns and trophic relationships is lacking. We examined diet composition and selectivity in a large-bodied insect, the Auckland tree wētā Hemideina thoracica , in three habitat zones in a lowland New Zealand forest. We asked whether H. thoracica selectively forage from available plant food sources, and whether these choices were lipid-rich compared to nonpreferred available plants. We also identified the proportion of invertebrates in their frass as a proxy for omnivory. From reconnaissance plot sampling, together with fecal fragment analysis, we report that more than 93% of individual tree wētā had eaten invertebrates before capture. Additionally, wētā in the highest elevation hillslope habitat zone consumed significantly fewer species of plants on average than wētā on the low-elevation terrace habitat. Upper hillslope wētā also had the highest average number of invertebrate fragments in their frass, significantly more than wētā in the low-elevation terrace habitat zone. Wētā showed high variability in the consumption of fruit and seeds across all habitat zones. Generally, we did not observe diet differences between the sexes (although it appears that male wētā in the mid-hillslope habitat ate fruits and seeds more voraciously than females), suggesting that the sexes have similar niche breadths and display similar degrees of omnivorous behavior. Extraction of leaf lipids demonstrated a range of lipid content values in available plants, and Ivlev's Electivity Index indicated that plant species which demonstrated high electivity tended to have higher concentrations of lipids in their leaves. Our findings indicate that H. thoracica forage omnivorously and selectively, and hence play multiple roles in native ecosystems and food webs. Tree wētā are eating selectively across zones based on lipid content of native plants. In the terrace, wētā are eating significantly more plant species than the other two zones. The trend is for wētā to eat more invertebrates as elevation increases. Mid-hillslope wētā appear to eat more fruits and seeds, but this is driven by a couple of male individuals.
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  • 72
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    Wiley-Blackwell
    Publication Date: 2018-02-02
    Description: The diagnosis of Parkinson's disease (PD) still lacks objective diagnostic markers independent of clinical criteria. Cerebrospinal fluid ( CSF) samples from 36 PD and 42 age-matched control patients were subjected to inductively coupled plasma-sector field mass spectrometry and a total of 28 different elements were quantified. Different machine learning algorithms were applied to the dataset to identify a discriminating set of elements yielding a novel biomarker signature. Using 19 stably-detected elements, the extreme gradient tree boosting model showed the best performance in the discrimination of PD and control patients with high specificity and sensitivity (78.6% and 83.3%, respectively), re-classifying the training data to 100%. The 10 times 10-fold cross validation yielded a good AUROC of 0.83. Arsenic, magnesium and selenium all showed significantly higher mean CSF levels in the PD group compared to the control group (p = 0.01, p = 0.04 and p = 0.03). Reducing the number of elements to a discriminating minimum, we identified an elemental cluster (Se, Fe, As, Ni, Mg, Sr), which most importantly contributed to the sample discrimination. Selenium was identified as the element with the highest impact within this cluster directly followed by iron. After prospective validation, this elemental fingerprint in the CSF could have the potential to be used as independent biomarker for the diagnosis of PD. Next to their value as a biomarker, this data also argues for a prominent role of these highly discriminating six elements in the pathogenesis of PD. This article is protected by copyright. All rights reserved.
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  • 73
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    Wiley-Blackwell
    Publication Date: 2018-02-03
    Description: Many ectotherms show a decrease in body size with increasing latitude due to changes in climate, a pattern termed converse Bergmann's rule. Urban conditions—particularly warmer temperatures and fragmented landscapes—may impose stresses on development that could disrupt these body size patterns. To test the impact of urbanization on development and latitudinal trends in body size, we launched a citizen science project to collect periodical cicadas ( Magicicada septendecim ) from across their latitudinal range during the 2013 emergence of Brood II. Periodical cicadas are long-lived insects whose distribution spans a broad latitudinal range covering both urban and rural habitats. We used a geometric morphometric approach to assess body size and developmental stress based on fluctuating asymmetry in wing shape. Body size of rural cicadas followed converse Bergmann's rule, but this pattern was disrupted in urban habitats. In the north, urban cicadas were larger than their rural counterparts, while southern populations showed little variation in body size between habitats. We detected no evidence of differences in developmental stress due to urbanization. To our knowledge, this is the first evidence that urbanization disrupts biogeographical trends in body size, and this pattern highlights how the effects of urbanization may differ over a species’ range. To test the impact of urbanization on development and latitudinal trends in body size, we launched a citizen science project to collect periodical cicadas ( Magicicada septendecim ) from across their latitudinal range during the 2013 emergence of Brood II. We used a geometric morphometric approach to assess body size and developmental stress based on fluctuating asymmetry in wing shape.Body size of rural cicadas followed converse Bergmann's rule, but this pattern was disrupted in urban habitats.
    Electronic ISSN: 2045-7758
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  • 74
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    Wiley-Blackwell
    Publication Date: 2018-02-03
    Description: Precipitation changes the physiological characteristics of an ecosystem. Because land-surface models are often used to project changes in the hydrological cycle, modeling the effect of precipitation on the latent heat flux λE is an important aspect of land-surface models. Here, we contrast conditionally-sampled diel composites of the eddy-covariance fluxes from the Niwot Ridge Subalpine Forest AmeriFlux tower with the Community Land Model (CLM, version 4.5). With respect to measured λE during the warm-season: for the day following above-average precipitation, λE was enhanced at mid-day by ≈ 40 W m −2 (relative to dry conditions), and nocturnal λE increased from ≈ 10 W m −2 in dry conditions to over 20 W m −2 in wet conditions. With default settings, CLM4.5 did not successfully model these changes. By increasing the amount of time that rainwater was retained by the canopy/needles, CLM was able to match the observed mid-day increase in λE on a dry day following a wet day. Stable nighttime conditions were problematic for CLM4.5. Nocturnal CLM λE had only a small (≈ 3 W m −2 ) increase during wet conditions, CLM nocturnal friction velocity u * was smaller than observed u * , and CLM canopy air temperature was 2 °C less than those measured at the site. Using observed u * as input to CLM increased λE ; however, this caused CLM λE to be increased during both wet and dry periods. We suggest that sloped topography and the ever-present drainage flow enhanced nocturnal u * and λE . Such phenomena would not be properly captured by topographically blind land-surface models, such as CLM.
    Electronic ISSN: 1942-2466
    Topics: Geography , Geosciences
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  • 75
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    Wiley-Blackwell
    Publication Date: 2018-02-05
    Description: Plant litter decomposition is an essential ecosystem function that contributes to carbon and nutrient cycling in streams. Aquatic shredders, mainly macroinvertebrates, can affect this process in various ways; they consume leaf litter, breaking it down into fragments and creating suitable habitats or resources for other organisms through the production of fine particulate organic matter (FPOM). However, measures of litter-feeding traits across a wide range of aquatic macroinvertebrates are still rare. Here, we assessed the contributions of 11 species of freshwater macroinvertebrates to litter decomposition, by measuring consumption rate, FPOM production, and assimilation rate of highly decomposable ( Alnus glutinosa ) or poorly decomposable ( Quercus robur ) leaf litter types. In general, an increase in the quality of litter improved the litter consumption rate, and fungal conditioning of the leaf litter increased both the litter consumption rate and FPOM production. Macroinvertebrates specializing in leaf litter consumption also appeared to be the most sensitive to shifts in litter quality and the conditioning process. Contrary to expectations, the conditioning process did not increase the assimilation of low-quality litter. There was a strong correlation between the relative consumption rate (RCR) of the two litter types, and the relative FPOM production (RFP) was strongly correlated to the RCR. These findings suggest a consistent relationship between RCR and macroinvertebrate identity that is not affected by litter quality, and that the RFP could be inferred from the RCR. The varying responses of the macroinvertebrate feeding traits to litter quality and the conditioning process suggest that the replacement of a shredder invertebrate species by another species could have major consequences for the decomposition process and the detritus-based food web in streams. Further studies onto the importance of invertebrate identity and the effects of litter quality in a variety of freshwater ecosystems are needed to understand the whole ecosystem functioning and to predict its response to environmental changes. We assessed the contributions of 11 species of freshwater macroinvertebrates to litter decomposition, by measuring consumption rate, FPOM production, and assimilation rate of highly decomposable ( Alnus glutinosa ) or poorly decomposable ( Quercus robur ) leaf litter types. We found a strong variation in the responses of the macroinvertebrate feeding traits to the litter quality and to the conditioning process, suggesting that the replacement of a shredder invertebrate species by another species could have major consequences for the decomposition process and the detritus-based food web in streams.
    Electronic ISSN: 2045-7758
    Topics: Biology
    Published by Wiley-Blackwell
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  • 76
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    Wiley-Blackwell
    Publication Date: 2018-02-05
    Description: The study examines the basic morphological and ecological features of Dolly Varden from Lake Kronotskoe (Russia, Kamchatka). Seven valid morphs different in head proportions, feeding, timing, and place of spawning have been determined in this ecosystem. The basic morphometric characteristics clearly separate Lake Kronotskoe morphs from each other, as well as from its potential ancestor (Dolly Varden). According to CVA analysis, the most notable morphological characteristics determining the mouth position are the length of a lower jaw and rostrum. Furthermore, five of seven morphs inhabit different depth zones of the lake and feed on different food resources. Our data suggest that reproductive isolation may be maintained by temporal/spatial isolation for two morphs with lacustrine spawning, and by spatial isolation only for the rest of the morphs with riverine spawning. The sympatric diversity of the Lake Kronotskoe charrs is exceptionally wide, and there are no other examples for seven sympatric morphs of genus Salvelinus to coexist within a single ecosystem. This study puts forward a three-step hypothetical model of charr divergence in Lake Kronotskoe as a potential ground for future studies. The basic morphological and ecological features are examined for Dolly Varden from Lake Kronotskoe (Russia, Kamchatka). It was found that sympatric diversity of Lake Kronotskoe charrs is exceptionally wide, and there are no other examples for seven sympatric morphs of genus Salvelinus to coexist within a single ecosystem. In conclusion, on the basis of morphological and ecological features, we suggest a possible way of three-step sympatric speciation of charrs in this lake.
    Electronic ISSN: 2045-7758
    Topics: Biology
    Published by Wiley-Blackwell
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  • 77
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    Wiley-Blackwell
    Publication Date: 2018-02-07
    Print ISSN: 1757-1693
    Electronic ISSN: 1757-1707
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Wiley-Blackwell
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  • 78
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    Wiley-Blackwell
    Publication Date: 2018-02-07
    Description: Anisotropy of turbulence near the top of the stratocumulus-topped boundary layer (STBL) is studied using large-eddy simulation (LES) and measurements from the POST and DYCOMS-II field campaigns. Focusing on turbulence ∼100°m below the cloud top, we see remarkable similarity between daytime and nocturnal flight data covering different inversion strengths and free-tropospheric conditions. With λ denoting wavelength and z t cloud-top height, we find that turbulence at λ / z t ≃ 0.01 is weakly dominated by horizontal fluctuations, while turbulence at λ / z t  〉 1 becomes strongly dominated by horizontal fluctuations. Between are scales at which vertical fluctuations dominate. Typical-resolution LES of the STBL (based on POST flight 13 and DYCOMS-II flight 1) captures observed characteristics of below-cloud-top turbulence reasonably well. However, using a fixed vertical grid spacing of 5 m, decreasing the horizontal grid spacing and increasing the subgrid-scale mixing length leads to increased dominance of vertical fluctuations, increased entrainment velocity and decreased liquid water path. Our analysis supports the notion that entrainment parametrizations (e.g. in climate models) could potentially be improved by accounting more accurately for anisotropic deformation of turbulence in the cloud-top region. While LES has the potential to facilitate improved understanding of anisotropic cloud-top turbulence, sensitivity to grid spacing, grid-box aspect ratio, and subgrid-scale model needs to be addressed.
    Electronic ISSN: 1942-2466
    Topics: Geography , Geosciences
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  • 79
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    Wiley-Blackwell
    Publication Date: 2018-02-07
    Description: Large-scale weather forecasting and climate models are beginning to reach horizontal resolutions of kilometers, at which common assumptions made in existing parameterization schemes of subgrid-scale turbulence and convection—such as that they adjust instantaneously to changes in resolved-scale dynamics—cease to be justifiable. Additionally, the common practice of representing boundary-layer turbulence, shallow convection, and deep convection by discontinuously different parameterizations schemes, each with its own set of parameters, has contributed to the proliferation of adjustable parameters in large-scale models. Here we lay the theoretical foundations for an extended eddy-diffusivity mass flux (EDMF) scheme that has explicit time-dependence and memory of subgrid-scale variables and is designed to represent all subgrid-scale turbulence and convection, from boundary layer dynamics to deep convection, in a unified manner. Coherent up- and downdrafts in the scheme are represented as prognostic plumes that interact with their environment and potentially with each other through entrainment and detrainment. The more isotropic turbulence in their environment is represented through diffusive fluxes, with diffusivities obtained from a turbulence kinetic energy budget that consistently partitions turbulence kinetic energy between plumes and environment. The cross-sectional area of up- and downdrafts satisfies a prognostic continuity equation, which allows the plumes to cover variable and arbitrarily large fractions of a large-scale grid box and to have life cycles governed by their own internal dynamics. Relatively simple preliminary proposals for closure parameters are presented and are shown to lead to a successful simulation of shallow convection, including a time-dependent life cycle.
    Electronic ISSN: 1942-2466
    Topics: Geography , Geosciences
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  • 80
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    Wiley-Blackwell
    Publication Date: 2018-02-08
    Description: Many conventional General Circulation Models (GCMs) in the Global Land–Atmosphere Coupling Experiment (GLACE) tend to produce what is now recognized as overly strong Land–Atmosphere (L–A) coupling. We investigate the effects of cloud Superparameterization (SP) on L–A coupling on timescales beyond diurnal where it has been recently shown to have a favorable muting effect hydrologically. Using the Community Atmosphere Model v3.5 (CAM3.5) and its Superparameterized counterpart SPCAM3.5, we conducted soil moisture interference experiments following the GLACE and Atmospheric Model Intercomparison Project (AMIP) protocols. The results show that, on weekly-to-subseasonal timescales, SP also mutes hydrologic L–A coupling. This is detectable globally, and happens through the evapotranspiration–precipitation segment. But on seasonal timescales, SP does not exhibit detectable effects on hydrologic L–A coupling. Two robust regional effects of SP on thermal L–A coupling have also been explored. Over the Arabian Peninsula, SP reduces thermal L–A coupling through a straightforward control by mean rainfall reduction. More counterintuitively, over the Southwestern US and Northern Mexico, SP enhances the thermal L–A coupling in a way that is independent of rainfall and soil moisture. This signal is associated with a systematic and previously unrecognized effect of SP that produces an amplified Bowen ratio, and is detectable in multiple SP model versions and experiment designs. In addition to amplifying the present-day Bowen ratio, SP is found to amplify the climate sensitivity of Bowen ratio as well, which likely plays a role in influencing climate change predictions at the L–A interface.
    Electronic ISSN: 1942-2466
    Topics: Geography , Geosciences
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