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  • Wiley-Blackwell  (504,041)
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  • 1
    Publication Date: 2018-03-15
    Description: Metastatic castration-resistant prostate cancer (mCRPC) is a lethal form of treatment-resistant prostate cancer and poses significant therapeutic challenges. Deregulated receptor tyrosine kinase (RTK) signalling mediated by loss of tumour suppressor Sprouty2 (SPRY2) is associated with treatment resistance. Using pre-clinical human and murine mCRPC models, we show that SPRY2 deficiency leads to an androgen self-sufficient form of CRPC. Mechanistically, HER2-IL6 signalling axis enhances the expression of androgen biosynthetic enzyme HSD3B1 and increases SRB1-mediated cholesterol uptake in SPRY2-deficient tumours. Systemically, IL6 elevated the levels of circulating cholesterol by inducing host adipose lipolysis and hepatic cholesterol biosynthesis. SPRY2-deficient CRPC is dependent on cholesterol bioavailability and SRB1-mediated tumoral cholesterol uptake for androgen biosynthesis. Importantly, treatment with ITX5061, a clinically safe SRB1 antagonist, decreased treatment resistance. Our results indicate that cholesterol transport blockade may be effective against SPRY2-deficient CRPC. Tumour-induced IL6 modulates host lipid metabolism to drive treatment-resistant castration-resistant prostate cancer (CRPC). Blocking tumoral cholesterol uptake using SRB1 antagonist or restoring systemic cholesterol homeostasis using statins decreases treatment resistance.
    Print ISSN: 1757-4676
    Electronic ISSN: 1757-4684
    Topics: Medicine
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  • 2
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-15
    Description: Understanding how factors that vary in spatial scale relate to population abundance is vital to forecasting species responses to environmental change. Stream and river ecosystems are inherently hierarchical, potentially resulting in organismal responses to fine-scale changes in patch characteristics that are conditional on the watershed context. Here, we address how populations of two salamander species are affected by interactions among hierarchical processes operating at different scales within a rapidly changing landscape of the southern Appalachian Mountains. We modeled reach-level occupancy of larval and adult black-bellied salamanders ( Desmognathus quadramaculatus ) and larval Blue Ridge two-lined salamanders ( Eurycea wilderae ) as a function of 17 different terrestrial and aquatic predictor variables that varied in spatial extent. We found that salamander occurrence varied widely among streams within fully forested catchments, but also exhibited species-specific responses to changes in local conditions. While D. quadramaculatus declined predictably in relation to losses in forest cover, larval occupancy exhibited the strongest negative response to forest loss as well as decreases in elevation. Conversely, occupancy of E. wilderae was unassociated with watershed conditions, only responding negatively to higher proportions of fast-flowing stream habitat types. Evaluation of hierarchical relationships demonstrated that most fine-scale variables were closely correlated with broad watershed-scale variables, suggesting that local reach-scale factors have relatively smaller effects within the context of the larger landscape. Our results imply that effective management of southern Appalachian stream salamanders must first focus on the larger scale condition of watersheds before management of local-scale conditions should proceed. Our findings confirm the results of some studies while refuting the results of others, which may indicate that prescriptive recommendations for range-wide management of species or the application of a single management focus across large geographic areas is inappropriate.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 3
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    Wiley-Blackwell
    Publication Date: 2018-03-07
    Print ISSN: 0007-9235
    Electronic ISSN: 1542-4863
    Topics: Medicine
    Published by Wiley-Blackwell on behalf of American Cancer Society.
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  • 4
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    Publication Date: 2018-03-07
    Description: Diet regulation behavior can mediate the consequences of imbalanced diets for animal well-being, particularly for captive species that have little dietary choice. Dasyurids (carnivorous marsupials) are of conservation concern in Australia, and many species are in captive breeding programmes. However, their nutrient targets and dietary regulation behaviors are poorly understood, a limitation that may decrease the breeding success and well-being of captive animals. We tested how dietary protein content influenced the intake and utilization of nutrients, physical activity, and body mass of fat-tailed dunnarts Sminthopsis crassicaudata . Twelve adult dunnarts from six sibling pairs (one female and one male per pair) were provided ad libitum access to three diets in a repeated measures design: cat food, cat food supplemented with raw lean beef (1:1), and cat food supplemented with cooked lean beef (1:1). Food intake, activity level, and fecal output were measured daily. Dunnarts significantly decreased food intake, increased protein digestion, and physical activity, but body mass was unchanged when on the high-protein diet compared to the normal cat food diet. These observations suggest a capacity of dunnarts to maintain constant body mass using a dynamic balance of feeding, digestion, and activity. We also found a significant effect of family, with differences between families as large as the difference between the diet treatments, suggesting a genetic component to diet selection. The nutrient regulation responses of dunnarts to high-protein diets and the strong family effects provide important messages for the management of populations of small carnivores, including the aspects of dietary manipulation and conservation of genetic diversity. When challenged with diets with different protein components, the small marsupial carnivore, Sminthopsis crassicaudata, moderated food intake and increased activity when on a high-protein diet, but body mass did not change. Surprisingly, there was a large effect of their genetic background on activity and food consumption; this effect was as large as the effect from the diets and sends a cautionary message about assumptions concerning food consumption in captive and wild animals.
    Electronic ISSN: 2045-7758
    Topics: Biology
    Published by Wiley-Blackwell
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  • 5
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    Publication Date: 2018-03-07
    Description: Passeriformes is the largest and most diverse avian order in the world and comprises the Passeri and Tyranni suborders. These suborders constitute a monophyletic group, but differ in their ecology and history of occupation of South America. We investigated the influence of biogeographic history on functional and phylogenetic diversities of Passeri and Tyranni in forest and savanna habitats in the Brazilian Amazon. We compiled species composition data for 34 Passeriformes assemblages, 12 in savannas and 22 in forests. We calculated the functional (Rao's quadratic entropy, FD Q ) and phylogenetic diversities (mean pairwise distance, MPD, and mean nearest taxon distance, MNTD), and the functional beta diversity to investigate the potential role of biogeographic history in shaping ecological traits and species lineages of both suborders. The functional diversity of Passeri was higher than for Tyranni in both habitats. The MPD for Tyranni was higher than for Passeri in forests; however, there was no difference between the suborders in savannas. In savannas, Passeri presented higher MNTD than Tyranni, while in forest areas, Tyranni assemblages showed higher MNTD than Passeri. We found a high functional turnover (~75%) between Passeri and Tyranni in both habitats. The high functional diversity of Passeri in both habitats is due to the high diversity of ecological traits exhibited by species of this group, which enables the exploitation of a wide variety of resources and foraging strategies. The higher Tyranni MPD and MNTD in forests is likely due to Tyranni being older settlers in this habitat, resulting in the emergence and persistence of more lineages. The higher Passeri MNTD in savannas can be explained by the existence of a larger number of different Passeri lineages adapted to this severe habitat. The high functional turnover between the suborders in both habitats suggests an ecological strategy to avoid niche overlap. We investigated the functional and phylogenetic diversity of Passeriformes (Passeri and Tyranni suborders) in Amazonian, and the functional beta diversity. The patterns of functional and phylogenetic diversity were a result of both the biogeographic history of each bird group, the occurrence within each habitat type, as well as the different ecological strategies shown by the species.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 6
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    Wiley-Blackwell
    Publication Date: 2018-03-07
    Description: The concept of niche partitioning has received considerable theoretical attention at the interface of ecology and evolution of infectious diseases. Strain theory postulates that pathogen populations can be structured into distinct nonoverlapping strains by frequency-dependent selection in response to intraspecific competition for host immune space. The malaria parasite Plasmodium falciparum presents an opportunity to investigate this phenomenon in nature, under conditions of high recombination rate and extensive antigenic diversity. The parasite's major blood-stage antigen, Pf EMP1, is encoded by the hyperdiverse var genes. With a dataset that includes thousands of var DBLα sequence types sampled from asymptomatic cases within an area of high endemicity in Ghana, we address how var diversity is distributed within isolates and compare this to the distribution of microsatellite allelic diversity within isolates to test whether antigenic and neutral regions of the genome are structured differently. With respect to var DBLα sequence types, we find that on average isolates exhibit significantly lower overlap than expected randomly, but that there also exists frequent pairs of isolates that are highly related. Furthermore, the linkage network of var DBLα sequence types reveals a pattern of nonrandom modularity unique to these antigenic genes, and we find that modules of highly linked DBLα types are not explainable by neutral forces related to var recombination constraints, microsatellite diversity, sampling location, host age, or multiplicity of infection. These findings of reduced overlap and modularity among the var antigenic genes are consistent with a role for immune selection as proposed by strain theory. Identifying the evolutionary and ecological dynamics that are responsible for the nonrandom structure in P. falciparum antigenic diversity is important for designing effective intervention in endemic areas. In this study, we test the hypothesis of niche partitioning to reduce trait overlap within a local community of Plasmodium falciparum strains. We examine patterns of diversity within the parasite's major blood-stage antigen, which is likely the playing field for parasite competition over host immune space. We observe reduced overlap among isolates and modularity among antigenic types—indications that niche partitioning is promoting the coexistence of distinct strains within this highly endemic community despite recombination through high multiplicity of infection.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 7
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    Wiley-Blackwell
    Publication Date: 2018-03-07
    Description: The reproductive stages of the life cycle are crucial in explaining the distribution patterns of plant species because of their extreme vulnerability to environmental conditions. Despite reported evidence that seed germination is related to habitat macroclimatic characteristics, such as mean annual temperature, the effect of this trait in controlling plant species distribution has not yet been systematically and quantitatively evaluated. To learn whether seed germination can predict species distribution along altitude gradients, we examined germination data of 36 Rhododendron species in southeastern Tibet originating from contrasting altitudes, habitats, plant heights, seed masses, and phylogenies. Germination varied significantly with altitude, habitat, plant height, and phylogeny and was higher in the light than in the dark. Germination percentage was highest at 10:20°C in the light and 15:25°C in the dark. As altitude increased, germination percentages first rose and then decreased, being highest at 3,500–4,000 m. Germination percentage and rate were highest on rocky slopes, increasing as seed mass and plant height rose. Variations in germination percentage and rate were not significant at subgenera, section, and subsection levels, but they were significant at species level. The results suggested that the relationship between germination and altitude may provide insights into species distribution patterns. Further, germination patterns are a result of long-term evolution as well as taxonomic constraints. The reproductive stages of the life cycle are crucial in explaining the distribution patterns of plant species because of their extreme vulnerability to environmental conditions. Phylogeny, habitat together with biological and ecological factors can influence germination of 36 subalpine Rhododendron species from the eastern Tibetan Plateau.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 8
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    Wiley-Blackwell
    Publication Date: 2018-03-07
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 9
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-07
    Description: Spatial variation in fish densities across river networks suggests that the influence of food and habitat resources on assemblages varies greatly throughout watersheds. Conceptual models predict that in situ primary production should vary with river characteristics, but the influence of autochthonous resource availability on the capacity for river reaches to support fish is poorly understood. We estimated primary production throughout the South Fork and Middle Fork of the John Day River, Oregon, by measuring diel cycles in dissolved oxygen (DO) during July 2013. Using these data, we (1) evaluated the extent to which juvenile salmonid abundance and resource limitation correlated with areas of high gross primary production (GPP), (2) developed models to predict GPP from both site-level measurements and remotely sensed data, and (3) made predictions of GPP across the entirety of the Middle Fork John Day River (MFJD) network and assessed the utility of these spatially continuous predictions for describing variation fish densities at broad scales. We produced reliable estimates of GPP at sites where DO loggers were deployed using measurements of solar exposure, water temperature, and conductivity measured at each site, as well as surrogates for these data estimated from remote sensing data sources. Estimates of GPP across fish sampling sites explained, on average, 58–63% of the variation in juvenile salmonid densities during the summer sampling period, and 51–83% during the fall sampling period, while continuous network predictions of GPP explained 44% of the variation in fish densities across 29 km of the MFJD. Further, GPP explained nearly half of the variation in juvenile steelhead dietary resource limitation, as inferred from bioenergetics modeling results. These results comprise a first effort at quantifying variation in autochthonous production across an entire river network and, importantly, provide a much-needed food-web context for guiding more effective fish and habitat management.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 10
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    Wiley-Blackwell
    Publication Date: 2018-03-07
    Print ISSN: 0007-9235
    Electronic ISSN: 1542-4863
    Topics: Medicine
    Published by Wiley-Blackwell on behalf of American Cancer Society.
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  • 11
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    Wiley-Blackwell
    Publication Date: 2018-03-07
    Description: A homogenization algorithm for randomly distributed microstructures is applied to develop a mass diffusion model for dry snow. Homogenization is a multi-scale approach linking constituent behavior at the microscopic level—amongst ice and air—to the macroscopic material—snow. Principles of continuum mechanics at the microscopic scale describe water vapor diffusion across an ice grain's surface to the air-filled pore space. Volume averaging and a localization assumption scale up and down, respectively, between microscopic and macroscopic scales. The model yields a mass diffusivity expression at the macroscopic scale that is, in general, a 2 nd order tensor parameterized by both bulk and microstructural variables. The model predicts a mass diffusivity of water vapor through snow that is less than that through air. Mass diffusivity is expected to decrease linearly with ice volume fraction. Potential anisotropy in snow's mass diffusivity is captured due to the tensor representation. The tensor is built from directional data assigned to specific, idealized microstructural features. Such anisotropy has been observed in the field and laboratories in snow morphologies of interest such as weak layers of depth hoar and near-surface facets.
    Electronic ISSN: 1942-2466
    Topics: Geography , Geosciences
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  • 12
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    Wiley-Blackwell
    Publication Date: 2018-03-07
    Description: Trade-offs associated with sexual size dimorphism (SSD) are well documented across the Tree of Life. However, studies of SSD often do not consider potential investment trade-offs between metabolically expensive structures under sexual selection and other morphological modules. Based on the expectations of the expensive tissue hypothesis, investment in one metabolically expensive structure should come at the direct cost of investment in another. Here, we examine allometric trends in the ontogeny of oyster toadfish ( Opsanus tau ) to test whether investment in structures known to have been influenced by strong sexual selection conform to these expectations. Despite recovering clear changes in the ontogeny of a sexually selected trait between males and females, we find no evidence for predicted ontogenetic trade-offs with metabolically expensive organs. Our results are part of a growing body of work demonstrating that increased investment in one structure does not necessarily drive a wholesale loss of mass in one or more organs. Organisms are faced with a finite energy budget with which to accumulate biomass in developing tissues, raising the question of how sexual selection imposes trade-offs in organ investment. We test the expectations of the expensive tissue hypothesis (ETH) across the ontogeny of oyster toadfishes, a species in which males are under strong sexual selection for a metabolically expensive acoustic repertoire that involves maintaining the fastest twitching muscles of any vertebrates. However, despite finding clear evidence of sexual dimorphism, we failed to recover any evidence supporting the expectations of the ETH.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 13
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    Wiley-Blackwell
    Publication Date: 2018-03-07
    Description: Southwest China is an important biodiversity hotspot. The interactions among the complex topography, climate change, and ecological factors in the dry-hot valley areas in southwest China may have profoundly affected the genetic structure of plant species in this region. In this study, we determined the effects of the Tanaka Line on genetic variation in the wild Bombax ceiba tree in southwest China. We sampled 224 individuals from 17 populations throughout the dry-hot valley regions. Six polymorphic expressed sequence tag–simple sequence repeat primers were employed to sequence the PCR products using the first-generation Sanger technique. The analysis based on population genetics suggested that B. ceiba exhibited a high level of gene diversity ( H E : 0.2377–0.4775; I : 0.3997–0.7848). The 17 populations were divided into two groups by cluster analysis, which corresponded to geographic characters on each side of the Tanaka Line. In addition, a Mantel test indicated that the phylogeographic structure among the populations could be fitted to the isolation-by-distance model ( r 2  = .2553, p  〈 .001). A barrier test indicated that there were obstacles among populations and between the two groups due to complex terrain isolation and geographic heterogeneity. We inferred that the Tanaka Line might have promoted the intraspecific phylogeographic subdivision and divergence of B. ceiba . These results provide new insights into the effects of the Tanaka Line on genetic isolation and population differentiation of plant species in southwest China. In the study, we used six pairs of EST-SSR primers to explore population structure and diversity of B .  cieba wild populations from both sides of Tanaka Line. Moreover, we used the Sanger sequencing of PCR products to make the results more accurate and reliable.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 14
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    Wiley-Blackwell
    Publication Date: 2018-03-07
    Description: Resource selection functions (RSFs) are tremendously valuable for ecologists and resource managers because they quantify spatial patterns in resource utilization by wildlife, thereby facilitating identification of critical habitat areas and characterizing specific habitat features that are selected or avoided. RSFs discriminate between known-use resource units (e.g., telemetry locations) and available (or randomly selected) resource units based on an array of environmental features, and in their standard form are performed using logistic regression. As generalized linear models, standard RSFs have some notable limitations, such as difficulties in accommodating nonlinear (e.g., humped or threshold) relationships and complex interactions. Increasingly, ecologists are using flexible machine-learning methods (e.g., random forests, neural networks) to overcome these limitations. Herein, we investigate the seasonal resource selection patterns of mule deer ( Odocoileus hemionus ) by comparing a logistic regression framework with random forest (RF), a popular machine-learning algorithm. Random forest (RF) models detected nonlinear relationships (e.g., optimal ranges for slope and elevation) and complex interactions which would have been very challenging to discover and characterize using standard model-based approaches. Compared with standard RSF models, RF models exhibited improved predictive skill, provided novel insights about resource selection patterns of mule deer, and, when projected across a relevant geographic space, manifested notable differences in predicted habitat suitability. We recommend that wildlife researchers harness the strengths of machine-learning tools like RF in addition to “classical” tools (e.g., mixed-effects logistic regression) for evaluating resource selection, especially in cases where extensive telemetry data sets are available. Resource selection functions (RSFs, which discriminate between used and available habitats on the basis of environmental features) are widely used by ecologists and resource managers but traditional approaches (generalized linear models) have limited power to detect and characterize nonlinear responses and complex interactions. Using a population of GPS-collared migratory mule deer in Nevada, USA, as a case study, we contrasted a classical RSF approach (mixed-effects logistic regression) with a more flexible machine-learning approach (random forest). The machine-learning approach provided important insights about seasonal resource selection patterns of mule deer that would have been difficult or impossible to achieve using classical RSF methods, leading us to conclude that machine-learning methods can complement and extend classical RSF approaches, especially in cases where extensive telemetry data sets are available.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 15
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-07
    Description: A human-made environmental disaster due to the shipwrecked of Costa Concordia cruise vessel on the Tuscan Island of Giglio (Italy) coast and the possible pollutants release has been feared, so requiring the activation of removal operations and the monitoring of the marine environment. In the present study, the seagrass Posidonia oceanica (L.) Delile was used as a bioindicator for the impact of the Costa Concordia accident on the marine and coastal habitat. Different P. oceanica samples were collected in the shipwrecked site under different light conditions. Using high-performance thin-layer chromatography, metabolic analysis of the samples was carried out in order to highlight possible changes in the secondary metabolism due to the permanent shading and the presence of pollutant traces. Moreover, sample mutagenicity, as a consequence of the possible absorption of environmental toxicants leaked by the wreck, was assessed by the Ames test. The results highlighted the permanence of the Concordia-induced alteration in the plant secondary metabolites. However, absorption of chemical pollutants and carcinogens was not reported; this point was confirmed by the lack of mutagenic effects found for the samples tested. Our results clearly evidence that the environmental impact of Costa Concordia wreck and removal operations on P. oceanica was mainly due to the lack of light in the marine habitat. Present methodological approach, which combines metabolomic and genetic ecotoxicological analysis, could represent a suitable strategy to evaluate the impact of human disasters on the ecosystem and to monitor the environmental changes.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 16
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-07
    Description: Sea scallops ( Placopecten magellanicus ) live along the Northwest Atlantic continental shelf and are aggregated over a broad range of spatial scales (m 2 –10 5  km 2 ). However, little is known about the spatial distribution of local scallop neighborhoods, the scale at which spawning, intra-specific competition, and predator–prey interactions occur. We surveyed 30,995 km 2 of Georges Bank and the Great South Channel annually from 2003 to 2010 counting the number of scallops in 54,016 locally replicated 3.24-m 2 quadrats with underwater video. There were about 4 billion scallops occupying 11,200 km 2 of the study area in concentrations from 1 to 41 scallops per scallop. Scallop spatial distribution switched from dispersed to aggregated at a concentration of 3–4 scallops in every year. High concentrations (〉3) occurred in 11% but were only persistent in 4% (449 km 2 ) of scallop habitat. There were 13 persistent high-concentration aggregations (7–217 km 2 ), and all but two occurred on gravel-dominated sediments left by prehistoric glacial retreat. Model-derived benthic boundary shear stresses in the persistent aggregations averaged two times higher than in scallop habitat, but the seabed was about two times more stable because it had significantly less sand and more granule–pebble and cobble sediment. The area occupied by scallops each year varied little (9%) despite a 49% increase in total scallop abundance between 2005 and 2007, suggesting Georges Bank scallops have a proportional density population structure. Most scallops occurred alone or at low concentrations (≤2) where fertilization success is probably poor. The persistent high-concentration aggregations we identified may be critical for successful reproduction and sustainable harvest. Observing organisms at scales corresponding to their individual interactions reveals important processes shaping their landscape-scale spatiotemporal distributions. These processes are obscured by the methods typically employed to estimate abundances of commercial fishery species. The spatiotemporal structure of sea scallop distribution has important implications for the design of abundance surveys and the assumptions underlying stock assessment methods. These should be investigated. Finally, this work suggests that natural disturbance (sediment stability) may play a substantial role in shaping spatiotemporal distributions and dynamics of benthic marine populations.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 17
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-07
    Description: Terrestrial organic matter (TOM) constitutes an important source of energy in many aquatic environments. This is the first study to compare the consumption of terrestrial leaves ( Alnus rubra ) to high-quality ( Nereocystis luetkeana ) and low-quality ( Fucus gardneri ) sources of drift kelp and low-quality seagrass ( Phyllospadix spp.) in pools of the rocky intertidal zone on Cape Arago, Oregon, USA. On average, 1.02 kg ash-free dry mass (AFDM) per day of TOM was transported by small forested streams during fall leaf abscission to the rocky intertidal zone in small pocket bays. Leaves of A. rubra (red alder) varied in wrack from negligible (12 g AFDM/m 2 ) on some beaches to the primary source of detritus on others (256 g AFDM/m 2 ). Long-term feeding experiments (months) showed that consumption rates of A. rubra in the spring (19.7% of the initial pack biomass) and in the fall (52% of the initial pack biomass) were intermediate between those of N. luetkeana (fully consumed) and Phyllospadix spp. (never 〉10% consumed of the initial pack biomass). Long-term experiments also showed that conditioned fall-shed leaves of A. rubra were consumed at a faster rate (52.3% of initial pack biomass) than spring-shed leaves of A. rubra (16.8% of initial pack biomass). Short-term feeding experiments again showed that consumption of A. rubra in the spring (18.6% of initial pack biomass over 3 d) and fall (16.7% over 7 d) was intermediate between N. luetkeana (57.3% consumed over 3 d in the spring and 60.7% over 7 d in the fall) and Phyllospadix spp. (〈1% consumed in the spring). Except for Phyllospadix spp., consumption rates followed polyphenolic concentrations in that, N. luetkeana (418 mg/mL) 〉  A. rubra (3415 mg/mL) 〉  F. gardneri (8098 mg/mL). Phyllospadix spp. was rarely consumed despite a fairly low concentration of phenolics (800 mg/mL). In the temperate zone, leaves of A .  rubra may constitute an important source of energy during the fall and winter when more nutritious marine resources dieback, such as single-celled algae and kelp (e.g., N. luetkeana ).
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 18
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-07
    Description: Foundation species are locally abundant and uniquely control associated biodiversity, whereas dominant species are locally abundant but are thought to be replaceable in ecological systems. It is important to distinguish foundation from dominant species to direct conservation efforts. Long-term studies that remove abundant species while measuring community dynamics have the potential to (1) aid in the identification of foundation vs. dominant species and, (2) once a foundation species is identified, determine how long its effects persist within a community after its loss. Long-term data on ant assemblages within two canopy-manipulation experiments—the Harvard Forest Hemlock Removal Experiment (HF-HeRE) and the Black Rock Future of Oak Forests Experiment (BRF-FOFE)—provide insights into how ant assemblages change and reassemble following the loss of Tsuga canadensis or Quercus spp. Previous research documented foundation species effects on ants in the HF-HeRE for up to four years after T. canadensis loss. Six additional years of data at HF-HeRE presented for the first time here show that removal of T. canadensis resulted in taxonomic and some measures of functional shifts in ant assemblages that persisted for ten years, further supporting the hypothesis that T. canadensis is a foundation species at Harvard Forest. In contrast, ant assemblages at BRF-FOFE varied little regardless of whether oaks or other tree species were removed from the canopy, suggesting that Quercus species do not act as foundation species at Black Rock Forest. Deer and moose exclosures within each experiment also allowed for comparisons between effects on ants of foundation or dominant tree species relative to effects of large herbivores. At HF-HeRE, effects of T. canadensis were stronger than effects of large herbivores on taxonomic and functional diversity of ant assemblages. At BRF-FOFE, in contrast, effects of Quercus species were weaker than effects of large herbivores on ant taxonomic diversity and some measures of ant functional diversity. These findings illustrate the importance of distinguishing between the roles of irreplaceable foundation species and replaceable dominant ones in forested ecosystems along with other drivers of biodiversity (e.g., herbivory).
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 19
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    Wiley-Blackwell
    Publication Date: 2018-03-07
    Description: In pediatric cancer, we advocate for trio sequencing of the child and its parents. This method can have substantial implications for cancer prevention in parents and siblings and even in more distant family members. It does not only help to identify a putative classical cancer predisposition syndrome in the index patient, but also detects the combinatorial effect of two independent risk variants in the same signaling pathway. This type of inheritance pattern could contribute to explaining the early occurrence of cancer in children and young adults and thereby inform early diagnosis, screening and preventive measures. From identifying a putative classical cancer predisposition syndrome in the index patient, trio-sequencing can also detect a potential combinatorial effect of two independent risk variants in the same signaling pathway. M. Kuhlen and A. Borkhardt explain here why they advocate for it.
    Print ISSN: 1757-4676
    Electronic ISSN: 1757-4684
    Topics: Medicine
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  • 20
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    Wiley-Blackwell
    Publication Date: 2018-03-07
    Description: Biogenic volatile organic compounds (BVOCs) are major precursors of both ozone and secondary organic aerosols (SOA) in the troposphere and represent a non-negligible portion of the carbon fixed by primary producers, but long-term ecosystem scale measurements of their exchanges with the atmosphere are lacking. In this study the fluxes of 46 ions corresponding to 36 BVOCs were continuously monitored along with the exchanges of mass (carbon dioxide, water vapour) and energy (sensible and latent heat) for an entire year in a poplar ( Populus ) short-rotation crop (SRC), using the eddy covariance methodology. BVOC emissions mainly consisted of isoprene, acetic acid and methanol. Total net BVOC emissions were 19.20 kg C ha −1 yr −1 , which represented 0.63% of the net ecosystem exchange (NEE), resulting from −23.59 Mg C ha −1 yr −1 fixed as CO 2 and 20.55 Mg C ha −1 yr −1 respired as CO 2 from the ecosystem. Isoprene emissions represented 0.293% of NEE, being emitted at a ratio of 1:1709 mol isoprene per mol of CO 2 fixed. Based on annual ecosystem-scale measurements this study quantified for the first time that BVOC carbon emissions were lower than previously estimated in other studies (0.5-2% of NEE) on poplar trees. Furthermore, the seasonal and diurnal emission patterns of isoprene, methanol and other BVOCs provided a better interpretation of the relationships with ecosystem CO 2 and water vapour fluxes, with air temperature, vapour pressure deficit and photosynthetic photon flux density. 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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  • 21
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    Wiley-Blackwell
    Publication Date: 2018-03-09
    Description: Alarm signals released after predator attack function as reliable public information revealing areas of high risk. The utility of this information can extend beyond species boundaries, benefiting heterospecifics capable of recognizing and responding appropriately to the signal. Nonmutually exclusive hypotheses explaining the acquisition of heterospecific reactivity to cues suggest it could be conserved phylogenetically following its evolution in a common ancestor (a species-level effect) and/or learned during periods of shared risk (a population-level effect; e.g., shared predators). Using a laboratory-based space-use behavioral assay, we tested the response of sea lamprey ( Petromyzon marinus ) to the damage-released alarm cues of five confamilial (sympatric and allopatric) species and two distantly related out-groups: a sympatric teleost (white sucker Catostomus commersonii ) and an allopatric agnathan (Atlantic hagfish Myxine glutinosa ). We found that sea lamprey differed in their response to conspecific and heterospecific odors; exhibiting progressively weaker avoidance of cues derived from more phylogenetically distant confamilials regardless of current overlap in distribution. Odors from out-groups elicited no response. These findings suggest that a damage-released alarm cue is at least partially conserved within the Petromyzontidae and that sea lamprey perceives predator attacks directed to closely related taxa. These findings are consistent with similar observations from gastropod, amphibian and bony fish taxa, and we discuss this in an eco-evo context to provide a plausible explanation for the acquisition and maintenance of the response in sea lamprey. Alarm signals released after predator attack function as reliable public information revealing areas of high risk. Using a laboratory-based space-use behavioral assay, we tested the response of sea lamprey ( Petromyzon marinus ) to the damage-released alarm cues of five confamilial (sympatric and allopatric) species and two distantly related out-groups: a sympatric teleost and a marine agnathan. We found that sea lamprey exhibited progressively weaker avoidance of cues derived from more phylogenetically distant confamilials regardless of current overlap in distribution, whereas odors from out-groups elicited no response.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 22
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-09
    Description: Unmanned aerial vehicles (UAVs) are increasingly being recognized as potentially useful for detection of marine mammals in their natural habitats, but an important consideration is the associated uncertainties in animal detection. We present a study based on field trials using UAVs to carry out image-based monitoring of cetaceans in two fjords in northern Norway. We conducted 12 missions to assess the effects of both environmental- and aircraft-related variables on detection certainty. Images were inspected for animal presence and its associated detection certainty. Images were also assessed for potentially important covariates such as wave turbulence (sea state), luminance, and glare. Aircraft variables such as altitude, pitch, and roll were combined into a single variable—pixel size. We recorded a total of 50 humpback whales, 63 killer whales (KW), and 118 unidentified sightings. We also recorded 57 harbor porpoise sightings. None of the environmental conditions (sea state, glare, and luminance) affected the detection certainty of harbor porpoises. In contrast, increasing sea state and luminance had negative and positive effects, respectively, on the detection certainty of humpback and KW. The detection certainty was not significantly affected by pixel size for both harbor porpoises, and humpback and KW. Our results indicate that at lower altitudes, variations in aircraft position (pitch and roll) do not have a variable effect on detection certainty. Overall, this study shows the importance of measuring variability in both environmental and flight-related variables, in order to attain unbiased estimates of detectability for UAV-based marine mammal surveys, particularly in Arctic and sub-Arctic regions.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 23
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    Wiley-Blackwell
    Publication Date: 2018-03-13
    Description: Biomarkers for α-synuclein are needed for diagnosis and prognosis in Parkinson's disease (PD). Endogenous auto-antibodies to α-synuclein could serve as biomarkers for underlying synucleinopathy, but previous assessments of auto-antibodies have shown variability and inconsistent clinical correlations. We hypothesized that auto-antibodies to α-synuclein could be diagnostic for PD and explain its clinical heterogeneity. To test this hypothesis, we developed an enzyme-linked immunosorbent assay for measuring α-synuclein auto-antibodies in human samples. We evaluated 69 serum samples (16 healthy controls (HC) and 53 PD patients) and 145 CSF samples (52 HC and 93 PD patients) from our Institution. Both serum and CSF were available for 24 participants. Males had higher auto-antibody levels than females in both fluids. CSF auto-antibody levels were significantly higher in PD patients as compared to HC, whereas serum levels were not significantly different. CSF auto-antibody levels did not associate with amyloid-β 1-42 , total tau, or phosphorylated tau. CSF auto-antibody levels correlated with performance on the Montreal Cognitive Assessment, even when controlled for CSF amyloidβ 1-42 . CSF hemoglobin levels, as a proxy for contamination of CSF by blood during lumbar puncture, did not influence these observations. Using recombinant α-synuclein with N- and C-terminal truncations, we found that CSF auto-antibodies target amino acids 100 through 120 of α-synuclein. We conclude that endogenous CSF auto-antibodies are significantly higher in PD patients as compared to HC, suggesting that they could indicate the presence of underlying synucleinopathy. These auto-antibodies associate with poor cognition, independently of CSF amyloidβ 1-42 ., and target a select C-terminal region of α-synuclein. This article is protected by copyright. All rights reserved.
    Print ISSN: 0022-3042
    Electronic ISSN: 1471-4159
    Topics: Medicine
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  • 24
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    Wiley-Blackwell
    Publication Date: 2018-03-13
    Description: Epigenetic modifications through methylation of DNA and acetylation of histones modulate neuronal gene expression and regulate long-term memory. Earlier we demonstrated that scopolamine-induced decrease in memory consolidation is correlated with enhanced expression of hippocampal DNA methyltransferase 1 (DNMT1) and histone deacetylase 2 (HDAC2) in mice. DNMT1 and HDAC2 act together by recruiting a co-repressor complex and deacetylating the chromatin. The catalytic activity of HDACs is mainly dependent on its incorporation into multiprotein co-repressor complexes, among which SIN3A-HDAC2 co-repressor is widely studied to regulate synaptic plasticity. However, the involvement of co-repressor complex in regulating memory loss or amnesia is unexplored. The present study examines the role of co-repressor SIN3A in scopolamine-induced amnesia through epigenetic changes in the hippocampus. Scopolamine treatment remarkably enhanced hippocampal SIN3A expression in mice. To prevent such increase in SIN3A expression, we used hippocampal infusion of SIN3A-siRNA and assessed the effect of SIN3A silencing on scopolamine-induced amnesia. Silencing of SIN3A in amnesic mice reduced the binding of HDAC2 at neuronal immediate early genes (IEGs) promoter, but did not change the expression of HDAC2. Further, it increased acetylation of H3K9 and H3K14 at neuronal IEGs (Arc, Egr1, Homer1 and Narp) promoter, prevented scopolamine-induced downregulation of IEGs and improved consolidation of memory during novel object recognition task. These findings together suggest that SIN3A has a critical role in regulation of synaptic plasticity and might act as a potential therapeutic target to rescue memory decline during amnesia and other neuropsychiatric pathologies. This article is protected by copyright. All rights reserved.
    Print ISSN: 0022-3042
    Electronic ISSN: 1471-4159
    Topics: Medicine
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  • 25
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    Wiley-Blackwell
    Publication Date: 2018-03-13
    Description: Sepsis-associated encephalopathy (SAE), characterized as diffuse brain dysfunction and neurological manifestations secondary to sepsis, is a common complication in critically ill patients and can give rise to poor outcome, but understanding the molecular basis of this disorder remains a major challenge. Given the emerging role of G protein-coupled receptor 2 (GRK2), first identified as a G protein-coupled receptor (GPCR) regulator, in the regulation of non-GPCR-related molecules contributing to diverse cellular functions and pathology, including inflammation, we tested the hypothesis that GRK2 may be linked to the neuropathogenesis of SAE. When mouse MG6 microglial cells were challenged with lipopolysaccharide (LPS), GRK2 cytosolic expression was highly upregulated. The ablation of GRK2 by small interfering RNAs (siRNAs) prevented an increase in intracellular reactive oxygen species generation in LPS-stimulated MG6 cells. Furthermore, the LPS-induced upregulation of inducible nitric-oxide synthase expression and increase in nitric oxide production were negated by GRK2 inhibitor or siRNAs. However, GRK2 inhibition was without effect on overproduction of tumor necrosis factor-α, interleukin (IL)-6, and IL-1β in LPS-stimulated MG cells. In mice with cecal ligation and puncture-induced sepsis, treatment with GRK2 inhibitor reduced high levels of oxidative and nitrosative stress in the mice brains, where GRK2 expression was upregulated, alleviated neurohistological damage observed in cerebral cortex sections, and conferred a significant survival advantage to CLP mice. Altogether, these results uncover the novel role for GRK2 in regulating cellular oxidative and nitrosative stress during inflammation and suggest that GRK2 may have a potential as an intriguing therapeutic target to prevent or treat SAE. This article is protected by copyright. All rights reserved.
    Print ISSN: 0022-3042
    Electronic ISSN: 1471-4159
    Topics: Medicine
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  • 26
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    Wiley-Blackwell
    Publication Date: 2018-03-13
    Description: The indirect pathway striatal medium spiny projection neurons (iMSNs) are critical to motor and cognitive brain functions. These neurons express a high level of cAMP-increasing adenosine A2a receptors (A2aRs). However, the potential effects of cAMP production on iMSN spiking activity have not been established, and recording identified iMSNs in freely moving animals is challenging. Here we show that in the transgenic mice expressing cAMP-producing G protein G s -coupled designer receptor exclusively activated by designer drug (Gs-DREADD) in iMSNs, the baseline spike firing in MSNs is normal, indicating DREADD expression does not affect the normal physiology of these neurons. Intraperitoneal (IP) injection of the DREADD agonist clozapine-N-oxide (CNO; 2.5 mg/kg) increased the spike firing in 50% of the recorded MSNs. However, CNO did not affect MSN firing in Gs-DREADD negative mice. We also found that CNO injection inhibited the spike firing of globus pallidus external segment (GPe) neurons in Gs-DREADD positive mice, further indicating CNO excitation of iMSNs. Temporally coincident with these effects on spiking firing in the indirect pathway, CNO injection selectively inhibited locomotion in D2 Gs-DREADD mice. Taken together, our results strongly suggest that cAMP production in iMSNs can increase iMSN spiking activity and cause motor inhibition, thus addressing a long-standing question about the cellular functions of the cAMP-producing A2aRs in iMSNs. This article is protected by copyright. All rights reserved.
    Print ISSN: 0022-3042
    Electronic ISSN: 1471-4159
    Topics: Medicine
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  • 27
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    Wiley-Blackwell
    Publication Date: 2018-03-14
    Description: Environmental factors strongly influence the ecology and evolution of vector-borne infectious diseases. However, our understanding of the influence of climatic variation on host–parasite interactions in tropical systems is rudimentary. We studied five species of birds and their haemosporidian parasites ( Plasmodium and Haemoproteus ) at 16 sampling sites to understand how environmental heterogeneity influences patterns of parasite prevalence, distribution, and diversity across a marked gradient in water availability in northern South America. We used molecular methods to screen for parasite infections and to identify parasite lineages. To characterize spatial heterogeneity in water availability, we used weather-station and remotely sensed climate data. We estimated parasite prevalence while accounting for spatial autocorrelation, and used a model selection approach to determine the effect of variables related to water availability and host species on prevalence. The prevalence, distribution, and lineage diversity of haemosporidian parasites varied among localities and host species, but we found no support for the hypothesis that the prevalence and diversity of parasites increase with increasing water availability. Host species and host × climate interactions had stronger effects on infection prevalence, and parasite lineages were strongly associated with particular host species. Because climatic variables had little effect on the overall prevalence and lineage diversity of haemosporidian parasites across study sites, our results suggest that independent host–parasite dynamics may influence patterns in parasitism in environmentally heterogeneous landscapes. Our work focuses on the ecology and evolution of host–pathogen interactions in relation to environmental heterogeneity. We aimed to understand the role of water-related climatic variables on the prevalence, diversity, and distribution of avian malaria parasites in northern South America across a steep climatic gradient. We studied five codistributed bird species with contrasting ecologies and evolutionary histories. We took advantage of field methods in ecology and ornithology, molecular screening of parasites, and statistical methods to examine relationships between parasitic infections and climatic data derived from remote-sensed variables.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 28
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    Wiley-Blackwell
    Publication Date: 2018-03-14
    Description: Organisms commonly experience significant spatiotemporal variation in their environments. In response to such heterogeneity, different mechanisms may act that enhance ecological performance locally. However, depending on the nature of the mechanism involved, the consequences for populations may differ greatly. Building on a previous model that investigated the conditions under which different adaptive mechanisms (co)evolve, this study compares the ecological and evolutionary population consequences of three very different responses to environmental heterogeneity: matching habitat choice (directed gene flow), adaptive plasticity (associated with random gene flow), and divergent natural selection. Using individual-based simulations, we show that matching habitat choice can have a greater adaptive potential than plasticity or natural selection: it allows for local adaptation while protecting genetic polymorphism despite global mating or strong environmental changes. Our simulations further reveal that increasing environmental fluctuations and unpredictability generally favor the emergence of specialist genotypes but that matching habitat choice is better at preventing local maladaptation by individuals. This confirms that matching habitat choice can speed up the genetic divergence among populations, cause indirect assortative mating via spatial clustering, and hence even facilitate sympatric speciation. This study highlights the potential importance of directed dispersal in local adaptation and speciation, stresses the difficulty of deriving its operation from nonexperimental observational data alone, and helps define a set of ecological conditions which should favor its emergence and subsequent detection in nature. Organisms commonly experience significant spatiotemporal variation in their environment, and populations can respond to this via different mechanisms that enhance individual local performance. Using individual-based simulation modeling, we compared the ecological and evolutionary population consequences of matching habitat choice (directed gene flow) with those of more familiar mechanisms: adaptive plasticity (associated with random gene flow) and divergent natural selection. We confirm that matching habitat choice can speed up local adaptation and genetic divergence among populations and can cause indirect assortative mating via spatial clustering and hence facilitate sympatric speciation.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 29
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    Wiley-Blackwell
    Publication Date: 2018-03-14
    Electronic ISSN: 1942-2466
    Topics: Geography , Geosciences
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  • 30
    Publication Date: 2018-03-15
    Description: Climate-related impacts to marine ecosystems threaten the biological, social, and economic resilience of the United States fishing industry. Changes in ocean conditions and variability in fisheries productivity have stimulated an effort to integrate climate information into fisheries science and management processes to inform more responsive decision-making. However, institutional, capacity, and budget constraints within United States federal and state fisheries management agencies may hinder the potential to deliver climate-ready strategies for many fisheries. We examine whether adaptive co-management as a governance approach can enhance capacity and advance climate-ready fisheries objectives. Adaptive co-management may improve the quality of science and decision-making needed to prepare for and respond to impacts of climate change in fisheries by taking advantage of skills, technology, and funding often not optimally utilized under the current governance system. We focus on the potential to improve information flows as a means to achieve climate-ready fisheries via adaptive co-management, but suggest that a greater level of partnership in the management process may be possible in the future after a period of formal experimentation and learning. This article is protected by copyright. All rights reserved
    Print ISSN: 1755-263X
    Electronic ISSN: 1755-263X
    Topics: Biology
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  • 31
    Publication Date: 2018-03-15
    Description: Currently, human society is predominantly powered by fossil fuels—coal, oil and natural gas—yet also ultimately depends on goods and services provided by biodiversity. Fossil fuel extraction impacts biodiversity indirectly through climate change and by increasing accessibility, and directly through habitat loss and pollution. In contrast to the indirect effects, quantification of the direct impacts has been relatively neglected. To address this, we analyse the potential threat to 〉 37,000 species and 〉 200,000 protected areas globally from the locations of present and future fossil fuel extraction in marine and terrestrial environments. Sites that are currently exploited have higher species richness and endemism than unexploited sites, whereas known future hydrocarbon activities will predominantly move into less biodiverse locations. We identify 181 ‘high-risk’ locations where oil or gas extraction suitability coincides with biodiversity importance, making conflicts between extraction and conservation probable. In total, protected areas are located on US$3-15 trillion of unexploited hydrocarbon reserves, posing challenges and potentially opportunities for protected area management and sustainable financing. This article is protected by copyright. All rights reserved
    Print ISSN: 1755-263X
    Electronic ISSN: 1755-263X
    Topics: Biology
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  • 32
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    Wiley-Blackwell
    Publication Date: 2018-03-15
    Description: Tolerance may lessen when wildlife adversely impacts people. Models from psychology can help elucidate how people make judgements, why they act accordingly, and whether beliefs and norms influence support for policy and intervention. Working in a globally important region for tigers, we estimated hunting prevalence for this endangered species and three sympatric taxa using methods for asking sensitive questions. We also investigated the relative strength of ethnicity and social-psychological predictors in influencing intention to hunt. Men's behavioural intention and perceptions differed by species: pro-conservation values were most prevalent for tiger, weakest for wild boar. Perceived behavioural control was the strongest predictor of hunting-intention; affect and injunctive norms were also important. The prominence of affect in determining intention suggests increasing environmental knowledge is unlikely to curb hunting. However, existing norms could be leveraged to incentivise behaviour-change. Integrating behaviour-change models into conservation science is crucial where strategies require changes in people's actions. This article is protected by copyright. All rights reserved
    Print ISSN: 1755-263X
    Electronic ISSN: 1755-263X
    Topics: Biology
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  • 33
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    Wiley-Blackwell
    Publication Date: 2018-03-16
    Description: Changes in microclimate, soil physicochemical properties, understory vegetation cover, diversity, and composition as well as soil microbial community resulting from silvicultural practices are expected to alter soil food webs. Here, we investigated whether and how contrasting-sized canopy openings affect soil nematode community within a 30 year-aged spruce plantation. The results indicated that the responses of soil nematodes to canopy opening size were dependant on their feeding habit. The abundance of total nematodes and that of free-living nematodes was negatively correlated with soil bulk density, whereas the abundance of omnivore–predators was negatively correlated with soil bulk density and shrubs cover, respectively. The ratio of the sum abundance of predators and omnivores to the plant parasites’ abundance, Simpson's dominance index, Pielou's evenness index, and sigma maturity index, maturity index (MI), MI 2-5 , basal index, enrichment index, and structure index was sensitive to alteration in canopy opening size. Multivariate analysis indicated that thinning-induced gap size resulted in contrasting nematode assemblages. In conclusion, soil nematodes should be integrated as an indicator to monitor soil multifunctionality change due to thinning. The responses of soil nematodes to gap size varied with the guilds of nematodes. Fine root biomass was positively related to abundance of total nematodes and plant parasites, while total microbial biomass, gap size, and soil water content were positively correlated to omnivore–predators abundance. The Pielou's evenness index, structure index, and the ratio of predatory to parasites were sensitive to gap size change. Means with the same letter are not different at the 5% level of significance based on the Tukey’s honestly significant difference tests.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 34
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    Wiley-Blackwell
    Publication Date: 2018-03-16
    Description: Payments for ecosystem services (PES) are expected to promote ecological restoration while simultaneously improving human livelihoods. As an adaptive management tool, PES programs should be dynamic and adjusted according to changing natural and socio-economic contexts. Taking the implementation of China's famous ecological restoration policy known as the Grain for Green Program (GGP) in the Wolong National Nature Reserve as an example, we analyzed changes in the livelihood capitals and strategies of local households that had participated in the GGP over a 10-year period and discussed the implications of these changes for the next stage of the program's implementation. Data were collected from a locally implemented questionnaire in both 2004 and 2015. We found that local livelihood capitals and strategies had experienced dramatic change over the 10-year period. Natural capital decreased and was unequally distributed among local respondents. In terms of financial capital, despite that agricultural and nonagricultural income increased, compensation from the GGP decreased and did not keep pace with increasing cost of cropland, household income and more broadly national economic development and inflation. Regarding human capital, the local labor force is facing huge transformational pressures. In particular, there is a increase in the supply of local labor force aged between 21 and 40 and the implications of this for the future of the GGP should be given more attention. The findings have demonstrated that: Some changes in participants’ livelihood were expected by the GGP but were not evenly distributed among the participants; and PES programs are embedded in changing and multi-dimensional socio-economic contexts, and so their design and implementation must be coordinated with other related policies if they are to achieve long-term success. Participants’ livelihoods have changed much in 10 years since Grain for Green Program implementation. These changes would feedback on the program itself and its sustainability in the long term. Payment for ecosystem service should be adjusted according to changing situations.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 35
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-14
    Description: Species composition is constrained by two upper-level processes in ecological contexts where the dispersion of organisms is not severely limited, namely selection and ecological drift. This intuitive framework has motivated a constant flow of empirical models for linking the species matrix to the local environmental descriptors, in which the environment rarely explains more than 30–40% of the variation in species composition. In most cases, researchers only approximate the environmental axes that drive fitness differences between species, as the list of measured descriptors reflect both logistical constraints and hypothesis-driven questions. Moreover, contextual factors, such as the species pool size (SPS) and the spatial extent of the sampled area, could moderate species–environment associations through sampling effects and dispersal limitations. This study's objective was to quantify the influence of contextual factors (i.e., related to the circumstances in which the study was conducted) on the species–environment association strength on the basis of a synthesis of 156 models of forest bird communities. Our results reveal that factors related to the SPS and the number of independent environmental axes studied affect our capacity to detect selection, whereas spatial factors such as the study's spatial extent and latitude are less important determinants. The study context explains almost a third of the observed variation in the strength of the species–environment association. We conclude that strong species–environment associations can be found for properly designed studies of forest bird communities, which raises the question of whether ecologists have underestimated the importance of selection in community assembly processes.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 36
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-14
    Description: Management, environment, and agroecosystem type are key factors influencing photosynthetic carbon (C) uptake and C use efficiency (CUE), calculated as the ratio of net ecosystem production to gross ecosystem production (NEP:GEP). Current literature has mainly emphasized annual C balance in studies involving multiple years with continuous monitoring of ecosystem C fluxes, yet CUE has not been thoroughly analyzed during the growing season, particularly in paired comparisons of contrasting types of pasture under semiarid conditions. From 2009 through 2013, we used eddy covariance method to determine daily, seasonal, and annual C budgets in rainfed alfalfa ( Medicago sativa L.) and grass ecosystems subjected to periodic harvest (haying) near Mandan, North Dakota, USA. We found consistently higher magnitudes of C fluxes (ecosystem respiration [ER], NEP, GEP) and hay production in alfalfa than grassland. Leaf area and canopy nitrogen content per unit land area were key driving factors for daily, seasonal, and annual differences in C fluxes between agroecosystems. Net ecosystem C balance indicated C losses occurred through haying in both ecosystems, though no changes in soil C stocks were detected in either ecosystem over the course of the study. Mean NEP:GEP ratios (±standard error) during periods of steady carbon dioxide (CO 2 ) uptake before and after haying were 0.43 ± 0.01 and 0.26 ± 0.03 for alfalfa and grassland, respectively, implying more efficient C use in the former. Moreover, alfalfa had consistently greater CUE than grassland despite variations in sunlight, temperature, and precipitation within and between growing seasons. Ratios of ER to GEP were also repeatedly lower in alfalfa than grassland in all five growing seasons. Under drought conditions, we infer alfalfa roots accessed water in the soil profile unavailable to more shallow-rooted grass species. Overall, hayed alfalfa was more efficient and tolerant than grassland in assimilating and using atmospheric CO 2 under variable intra- and inter-seasonal conditions. Outcomes from this study suggest the inclusion of alfalfa in unirrigated crop rotations can sustain high CUE, C uptake, and hay production while mitigating C losses in a semiarid environment.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 37
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    Wiley-Blackwell
    Publication Date: 2018-03-14
    Description: Ectotherms tend to grow faster, but reach a smaller size when reared under warmer conditions. This temperature-size rule (TSR) is a widespread phenomenon. Despite the generality of this pattern, no general explanation has been found. We therefore tested the relative importance of two proposed mechanisms for the TSR: (1) a stronger increase in development rate relative to growth rate at higher temperatures, which would cause a smaller size at maturity, and (2) resource limitation placing stronger constraints on growth in large individuals at higher temperatures, which would cause problems with attaining a large size in warm conditions. We raised Daphnia magna at eight temperatures to assess their size at maturity, asymptotic size, and size of their offspring. We used three clonal lines that differed in asymptotic size and growth rate. A resource allocation model was developed and fitted to our empirical data to explore the effect of both mechanisms for the TSR. The genetic lines of D. magna showed different temperature dependence of growth and development rates resulting in different responses for size at maturity. Also, at warm temperatures, growth was constrained in large, but not in small individuals. The resource allocation model could fit these empirical data well. Based on our empirical results and model explorations, the TSR of D. magna at maturity is best explained by a stronger increase in development rate relative to growth rate at high temperature, and the TSR at asymptotic size is best explained by a size-dependent and temperature-dependent constraint on growth, although resource limitation could also affect size at maturity. In conclusion, the TSR can take different forms for offspring size, size at maturity, and asymptotic size and each form can arise from its own mechanism, which could be an essential step toward finding a solution to this century-old puzzle. Scientists have known that ectotherms tend to reach larger sizes when they grow in colder environments. We now identified three distinct patterns in this phenomenon and discuss how these patterns could be regulated by different physiological mechanisms. We use a novel resource allocation model to describe these patterns and to test the hypothesized mechanisms underlying them.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 38
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    Wiley-Blackwell
    Publication Date: 2018-03-14
    Description: Global change is affecting primary productivity in forests worldwide, and this, in turn, will alter long-term carbon (C) sequestration in wooded ecosystems. On one hand, increased primary productivity, for example, in response to elevated atmospheric carbon dioxide (CO 2 ), can result in greater inputs of organic matter to the soil, which could increase C sequestration belowground. On other hand, many of the interactions between plants and microorganisms that determine soil C dynamics are poorly characterized, and additional inputs of plant material, such as leaf litter, can result in the mineralization of soil organic matter, and the release of soil C as CO 2 during so-called “priming effects”. Until now, very few studies made direct comparison of changes in soil C dynamics in response to altered plant inputs in different wooded ecosystems. We addressed this with a cross-continental study with litter removal and addition treatments in a temperate woodland (Wytham Woods) and lowland tropical forest (Gigante forest) to compare the consequences of increased litterfall on soil respiration in two distinct wooded ecosystems. Mean soil respiration was almost twice as high at Gigante (5.0 μmol CO 2  m −2  s −1 ) than at Wytham (2.7 μmol CO 2  m −2  s −1 ) but surprisingly, litter manipulation treatments had a greater and more immediate effect on soil respiration at Wytham. We measured a 30% increase in soil respiration in response to litter addition treatments at Wytham, compared to a 10% increase at Gigante. Importantly, despite higher soil respiration rates at Gigante, priming effects were stronger and more consistent at Wytham. Our results suggest that in situ priming effects in wooded ecosystems track seasonality in litterfall and soil respiration but the amount of soil C released by priming is not proportional to rates of soil respiration. Instead, priming effects may be promoted by larger inputs of organic matter combined with slower turnover rates. Taken together, results of our cross-continental study with litter removal and addition treatments in a temperate woodland (Wytham Woods) and lowland tropical forest (Gigante forest) for comparing consequences of increased litterfall on soil respiration in two distinct wooded ecosystems showed that mean soil respiration was almost twice as high at Gigante than at Wytham but surprisingly, litter manipulation treatments had a greater and more immediate effect on soil respiration at Wytham. Importantly, despite higher soil respiration rates at Gigante, priming effects were stronger and more consistent at Wytham. Our results suggest that in situ priming effects in wooded ecosystems track seasonality in litterfall and soil respiration but the amount of soil C released by priming is not proportional to rates of soil respiration.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 39
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-14
    Description: Termite mounds perform important roles in savanna ecosystems, generating heterogeneity and influencing ecosystem processes across multiple trophic levels. However, the influence the environment and neighboring termite colonies have on mound spatial patterning and structure is poorly understood, despite the profound implications such dynamics can have on ecosystems. To better understand these drivers, we mapped the spatial distribution and size of active and inactive Macrotermes mounds in eight 1-km 2 plots on contrasting geologies, nutrient-rich granite and nutrient-poor basalt, in a semi-arid Zimbabwean savanna. Although mound density was not significantly different between basalt (5.5 mounds/ha) and granite (6.1 mounds/ha), termite mound structural attributes and spatial distribution patterns varied greatly between geologies. Mound size distributions differed between the geologies and mounds were 2.6 times taller and 3.9 times wider and had 15 times greater lateral surface area on granite. Subsequently, 6% of the total landscape was covered by mounds on granite compared with only 0.4% on basalt. On granite, large mounds exhibited significant over-dispersion at scales below 30 m, signifying density-dependent thinning. Furthermore, small mounds were clustered around large mounds, likely a result of the budding of new colonies comprising fully fledged castes less vulnerable to competition. In contrast, random patterning was evident on comparably homogenous basalt. Our results demonstrate the powerful influence geological substrate has on mound spatial patterning and structure, suggesting that the importance of termite mounds for ecosystem functioning is more pronounced on nutrient-poor granitic substrates than basalts because of the pronounced over-dispersion, which maximizes mound production per unit area, and much larger mound sizes here.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 40
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-14
    Description: For organisms with complex life cycles, climate change can have both direct effects and indirect effects that are mediated through plastic responses to temperature and that carry over beyond the developmental environment. We examined multiple responses to environmental warming in a dragonfly, a species whose life history bridges aquatic and terrestrial environments. We tested larval survival under warming and whether warmer conditions can create carry-over effects between life history stages. Rearing dragonfly larvae in an experimental warming array to simulate increases in temperature, we contrasted the effects of the current thermal environment with temperatures +2.5° and +5°C above ambient, temperatures predicted for 50 and 100 yr in the future for the study region. Aquatic mesocosms were stocked with dragonfly larvae ( Erythemis collocata ), and we followed survival of larvae to adult emergence. We also measured the effects of warming on the timing of the life history transition to the adult stage, body size of adults, and the relative size of their wings, an aspect of morphology key to flight performance. There was a trend toward reduced larval survival with increasing temperature. Warming strongly affected the phenology of adult emergence, advancing emergence by up to a month compared with ambient conditions. Additionally, our warmest conditions increased variation in the timing of adult emergence compared with cooler conditions. The increased variation with warming arose from an extended emergence season with fewer individuals emerging at any one time. Altered emergence patterns such as we observed are likely to place individuals emerging outside the typical season at greater risk from early and late season storms and will reduce effective population sizes during the breeding season. Contrary to expectations for ectotherms, body size was unaffected by warming. However, morphology was affected: at +5°C, dragonflies emerging from mesocosms had relatively smaller wings. This provides some of the first evidence that the effects of climate change on animals during their growth can have carry-over effects in morphology that will affect performance of later life history stages. In dragonflies, relatively smaller wings are associated with reduced flight performance, creating a link between larval thermal conditions and adult dispersal capacity.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 41
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-14
    Description: Interacting effects of climate change and livestock grazing on semi-arid grassland ecosystems have not been well studied, especially on a long-term basis. This paper analyzes changes in plant community composition in relation to grazing intensity and climate change based on repeated monitoring along long-term grazing intensity gradients in three Mongolian ecological zones over 20 yr. We synthesized our findings into state-and-transition models of vegetation change, contributing to our understanding of ecological dynamics in relation to management and environmental change, and to the development of tools for resilience-based rangeland management. In the mountain steppe (MS), community composition was driven largely by climate, and transitions from one community to another were associated with climate change or combined climate and grazing effects. The MS experienced the largest number of long-term transitions (14 of 15 plots) over 20 yr. In the steppe (ST), grazing intensity was the strongest influence on community composition, but transitions between communities from the early 1990s to 2013 were most strongly correlated with climate change. Ten of the 15 ST plots transitioned to other communities over 20 yr. Community composition in the desert steppe (DS) was unrelated to either grazing intensity or climate change and only six of 15 plots transitioned permanently over 20 yr. The MS appears most vulnerable to climate-induced community change, as others have suggested. Some degraded ST communities are resilient to climate change, while ST communities on drier sites are vulnerable to grazing-induced community changes. Our findings illustrate the utility of state-and-transition models as a means to synthesize and depict plant community dynamics in relation to climate and management factors. These models identify communities that may be growing rarer or more common under the combined effects of climate change and grazing, and highlight species and communities that may be useful conservation targets or indicators of climate- or grazing-induced change.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 42
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-02-27
    Description: Monitoring rodent abundance is critical to understand direct and indirect trophic interactions in most northern terrestrial ecosystems. However, logistic constraints can prevent researchers from using capture–mark–recapture methods, a robust approach to estimate abundance. Our objective was to determine the correlation between abundance estimates of Arctic lemmings obtained from live-trapping data with spatially explicit capture–recapture models (SECR; N/ha) and abundance indices obtained from snap-trapping along trap lines (N/100 trap-nights), winter nest sampling along transects with distance sampling models (N/ha), burrow counting within quadrats (N/100 m 2 ), and incidental observations (N/100 observer-hr). We also evaluated the impact of reduced sampling effort on the bias and precision of each abundance estimate. Data from brown ( Lemmus trimucronatus ) and collared lemmings ( Dicrostonyx groenlandicus ) were collected each year from 2007 to 2016 on Bylot Island, Nunavut, Canada. Snap-trapping ( r  =   0.90) and incidental observations ( r  =   0.92) yielded the highest correlations with live-trapping densities for brown lemmings, the most abundant species. When combining abundance of both lemming species, snap-trapping ( r  =   0.77) and incidental observations ( r  =   0.90) also yielded the highest correlations. Indices from winter nests and burrows were also correlated ( r  〉   0.50) with live-trapping densities, but to a lesser degree. We found that bias generally increased when effort was reduced for methods involving modeling of capture or detection probabilities (i.e., live-trapping, winter nests), but remained low for the other methods. In contrast, precision of estimates remained high when using SECR models, but decreased substantially for the other methods during years of low lemming abundance. Non-convergence of SECR and distance sampling models generally increased when reducing effort and was frequent in years of low lemming abundance. Interestingly, collecting 〉200 h of incidental observations generated highly reliable estimates of lemming abundance compared to results from live-trapping, indicating that such non-invasive method can provide valuable data at low cost. We provide guidelines on other invasive or non-invasive methods that can be used when small mammals cannot be live-trapped and suggest the effort required to achieve a given precision.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 43
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    Wiley-Blackwell
    Publication Date: 2018-02-27
    Description: O 6 -methylguanine DNA methyltransferase ( MGMT ) promoter methylation is a predictive biomarker for benefit from alkylating chemotherapy, specifically temozolomide (TMZ), in glioblastoma, the most common malignant intrinsic brain tumor. Glioma-initiating cells (GIC) with stem-like properties have been associated with resistance to therapy and progression. We assessed the levels of MGMT mRNA and MGMT protein by real-time PCR and immunoblot and evaluated the impact of MGMT on TMZ sensitivity in clonogenicity assays in GIC sphere cultures (S) or differentiated adherent monolayer cultures (M). Nuclear factor kappa B (NF-κB) signalling was assessed by reporter assay and immunoblot. Compared to M cells, S cells expressed higher levels of MGMT. Differentiation of GIC induced by S-to-M transition resulted in a gradual loss of MGMT expression and increased TMZ sensitivity. This transcriptional regulation of MGMT was restricted to cell lines without MGMT promoter methylation and was not coupled to any specific neurobasal (NB) stem cell medium supplement or loss of cell adhesion. Expression levels of p50/p65 subunits of NF-κB, a transcriptional regulator of MGMT , were increased in S cells. Inhibition of NF-κB by the small molecule inhibitor, BAY 11-7082, or siRNA-mediated gene silencing, reduced MGMT levels. In summary, alkylator resistance of S cells is mainly promoted by overexpression of MGMT which results from increased activity of the NF-κB pathway in this cell culture model of glioma stem-like cells. This article is protected by copyright. All rights reserved.
    Print ISSN: 0022-3042
    Electronic ISSN: 1471-4159
    Topics: Medicine
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  • 44
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-06
    Description: Structural habitat complexity (SHC) and functional habitat connectivity (FHC) are the basic components that make up the physical architecture of an ecosystem, and can have substantial impacts on predator–prey interactions. These structural components influence animal behaviors such as inter-patch movement, foraging, and competition, and can impact community structure/dynamics in terrestrial and aquatic ecosystems. The effects of SHC and FHC on predator–prey dynamics within an ecosystem may also have important cascading effects on neighboring ecosystems by altering the movement of individuals across ecosystem boundaries. For example, when aquatic insects emerge as adults, they enter terrestrial ecosystems where they become an important food resource for terrestrial predators. Using a multiple patch, predator enclosure design in ponds, we tested whether altering intra-patch plant stem densities (SHC) and inter-patch distances (FHC) would influence the impact a predatory fish has on the biomass, quality, and trophic composition of emergent insects. As expected, fish significantly reduced emergent insect biomass (33% ± 7.6, mean ± SE). Intra-patch stem densities (SHC) did not significantly alter fish effects; however, inter-patch distance (FHC) did significantly alter the impact of fish on the size of some emergent insects. Damselflies that emerged in treatments with fish present and shorter inter-patch distances were significantly larger, 4.1 ± 0.1 mg/m 2 compared to 3.3 mg/m 2  ± 0.1 in the long/fish treatments. In fish treatments, this effect on damselfly size resulted in greater reductions in total emergent insect biomass in long inter-patch distance treatments (47.3% ± 6.9) compared to short inter-patch distance treatments (20.5% ± 12.4). Our results suggest that physical components of a habitat, such as inter-patch distances, have important impacts on predator–prey dynamics within habitats. These altered predator–prey dynamics can then have cascading effects on adjacent habitats by influencing the abundance, trophic composition, and quality of exported trophic subsidies.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 45
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-06
    Description: Fire regimes have long-term effects on ecosystems which can be subtle, requiring study at a large spatial scale and temporal scale to fully appreciate. The way in which multiple fires interact to create a fire regime is poorly understood, and the relationship between the severities of consecutive fires has not been studied in Australia. By overlaying remotely sensed severity maps, our study investigated how the severity of a fire is influenced by previous fire severity. This was done by sampling points at 500-m spacing across 53 fires in dry eucalypt forests of southeast Australia, over a range of time since fire spanning every major fire season for 30 yr. Generalized additive models were used to determine the influence of previous severity on the probability of crown fire and understory fire, controlling for differences in time since fire, topography, and weather. We found that a crown fire is more than twice as likely after a previous crown fire than previous understory fire, and understory fire is more likely after previous understory fire. Our findings are in line with the results of studies from North America and suggest that severe fire promotes further fire. This may be evidence of a runaway positive feedback, which can drive ecological change, and lead to a mosaic of divergent vegetation, but research into more than two consecutive fires is needed to explore this. Our results also suggest that a low-severity prescribed fire may be a useful management option for breaking a cycle of crown fires.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 46
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    Wiley-Blackwell
    Publication Date: 2018-03-06
    Print ISSN: 1757-1693
    Electronic ISSN: 1757-1707
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 47
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    Wiley-Blackwell
    Publication Date: 2018-02-24
    Description: Hydrophobically modified acrylamide copolymers dewater oil sands tailings more effectively than anionic polyacrylamide, but the root causes for this enhanced performance have not been investigated systematically. Polyacrylamide-poly(ethylene oxide methyl ether methacrylate) copolymers with different comonomer compositions, hydrophobic chain lengths, and molecular weights to map out these effects systematically are synthetized. Through a statistical design of experiments, it is found out that all three variables above significantly affected flocculation performance and that certain combinations achieve optimal results. The effect of centrifugation on the flocculation and dewatering performance of these polymers is also investigated. This study proposes to dewater oil sands mature fine tailings (MFT) using hydrophobically modified copolymers of acrylamide, poly(acrylamide- co -ethylene oxide methyl ether methacrylate). Dewatering of MFT is systematically studied as a function of comonomer content, hydrophobic chain lengths, and copolymer molecular weight.
    Electronic ISSN: 2056-6646
    Topics: General, Interdisciplinary , Energy, Environment Protection, Nuclear Power Engineering
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  • 48
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-06
    Description: Plants interact with a variety of soil biota. The accumulation of beneficial or antagonistic biota over time can have strong positive or negative effects on the recruitment of new individuals into the population (i.e., plant–soil feedback, PSF). Despite the potential influence of PSF on plant diversity in terrestrial ecosystems, our understanding of its determinants remains incomplete. Within forests, recent evidence indicates that mycorrhizal type can regulate PSF: Arbuscular mycorrhizal trees typically experience negative PSF, while ectomycorrhizal trees experience positive PSF. Other studies have found that plant traits and the local environment also affect PSF; yet, these studies are based on arbuscular mycorrhizal plants in herbaceous systems. Consequently, the relationship between PSF and plant traits or the environment may depend on the mycorrhizal type of the tree. Using PSF measurements for 520 populations belonging to 52 North American temperate forest tree species, we tested whether mycorrhizal type influences how plant traits and climate relate to PSF. For both mycorrhizal types, species that produced larger seeds and were less drought tolerant had more positive (or less negative) PSF. Precipitation during the dry season was negatively related to PSF, but only for arbuscular mycorrhizal trees. These results suggest that investing more resources in seeds may minimize PSF for tree species, irrespective of mycorrhizal type. Species that have historically been exposed to greater pathogen abundances in wetter environments may also be better defended against attack, minimizing negative PSF. However, for species currently found in wetter environments, PSF may be strongly negative if their mycorrhizas do not defend them against attack, as is common among arbuscular mycorrhizal trees. Combined, these results highlight the importance of mycorrhizal type in determining the relationship between PSF and climate, but indicate that the relationship between PSF and plant traits may be independent of mycorrhizal type. Nevertheless, mycorrhizal type remains an important consideration when studying PSF, and forest dynamics in general.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 49
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    Wiley-Blackwell
    Publication Date: 2018-02-22
    Description: In many species, males increase their reproductive success by choosing high-quality females. In natural populations, they interact with both virgin and mated females, which can store sperm in their spermatheca. Therefore, males elaborate strategies to avoid sperm competition. In the terrestrial isopod Armadillidium vulgare , females can store sperm and produce several clutches. Moreover, this species can be parasitized by Wolbachia , which feminizes genetic males, transforming them into functional females. Our study compared attractiveness and mate choice when a male is exposed to both virgin and experienced females (i.e., females who have produced offspring and rested for 6 months), with or without Wolbachia . Our results revealed that males are more attracted to virgin females than experienced females, even if these virgin females are parasitized. Moreover, the chemical analysis highlighted different odors in females according to their reproductive and infection ( Wolbachia- free or vertically Wolbachia -infected) status. Males attempted copulation more frequently and for longer with virgin females, even if Wolbachia -infected, while experienced females refused further copulation. The evolutionary consequences of both male choice and female resistance on their fitness are discussed in this study. In the terrestrial isopod Armadillidium vulgare , infected with the feminizing bacteria Wolbachia, females can store sperm from previous matings. We investigated male mate choice when a male can choose between virgin and experienced (i.e., used 6 months after releasing their offspring) females. Our results suggest that males are able to recognize and prefer virgin females, even if females are infected with Wolbachia, whereas experienced females refused new mating.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 50
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    Wiley-Blackwell
    Publication Date: 2018-02-22
    Electronic ISSN: 2050-0505
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 51
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    Wiley-Blackwell
    Publication Date: 2018-02-22
    Description: The world conference (Conference of the Parties (COP23)) under the UN Framework Convention on Climate Change took place in Bonn (Germany) from 6 to 17 November. Speakers at the meeting stressed the severity of the threat from global warming and the urgent need to act but what commitments came out of the COP23 meeting? Alexandra Carrick gives a short summary of the meeting and some of the energy outcomes of the conference.
    Electronic ISSN: 2050-0505
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 52
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    Wiley-Blackwell
    Publication Date: 2018-02-22
    Description: The synthesis of silver nanoparticles (AgNPs) within the interlayer space of transparent layered titania nanosheet (TNS) films is investigated. A considerable number of silver ions (≈70% against the cation exchange capacity of the TNS) are intercalated in the TNS films using methyl-viologen-containing TNSs as a precursor. The silver ion (Ag + )-containing TNS films are treated with aqueous sodium tetrahydroborate (NaBH 4 ), resulting in a gradual color change to bright blue. Various structural analyses clearly show that crystalline AgNPs are generated within the interlayer space of the TNSs. The NaBH 4 -treated films show intense and characteristic near-infrared (NIR) extinction spectra up to 1800 nm. The stability of the AgNPs within the TNS against oxygen and moisture is also investigated, and 96% and 82% of the AgNPs remain after standing in air for 1 month and 1 year, respectively. The NIR extinctions of the AgNP-containing TNS films are further extended by employing different preparation procedures, for example, using sintered TNS films as starting materials and irradiating the Ag + -containing TNSs with ultraviolet (UV) light. The obtained AgNP-containing TNS films exhibit photochemical activities in the production of hydrogen from ammonia borane under visible-light irradiation and the decomposition of nitrogen monoxide under UV-light irradiation. The synthesis of silver nanoparticles within the interlayer spaces of layered titanate films and their optical and photochemical characteristics are investigated. The films show intense extinction from the visible to the near-infrared region and exhibit good stability in air. The films exhibit photochemical activities for hydrogen production from amminetrihydridoboron and nitric oxide decomposition.
    Electronic ISSN: 2056-6646
    Topics: General, Interdisciplinary , Energy, Environment Protection, Nuclear Power Engineering
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  • 53
    Publication Date: 2018-03-06
    Description: Despite the existence of well-established international environmental and nature conservation policies (e.g., the Ramsar Convention and Convention on Biological Diversity) ponds are largely missing from national and international legislation and policy frameworks. Ponds are among the most biodiverse and ecologically important freshwater habitats, and their value lies not only in individual ponds, but more importantly, in networks of ponds (pondscapes). Ponds make an important contribution to society through the ecosystem services they provide, with effective conservation of pondscapes essential to ensuring that these services are maintained. Implementation of current pond conservation through individual site designations does not function at the landscape scale, where ponds contribute most to biodiversity. Conservation and management of pondscapes should complement current national and international nature conservation and water policy/legislation, as pondscapes can provide species protection in landscapes where large-scale traditional conservation areas cannot be established (e.g., urban or agricultural landscapes). We propose practical steps for the effective incorporation or enhancement of ponds within five policy areas: through open water sustainable urban drainage systems in urban planning, increased incentives in agri-environment schemes, curriculum inclusion in education, emphasis on ecological scale in mitigation measures following anthropogenic developments, and the inclusion of pondscapes in conservation policy. This article is protected by copyright. All rights reserved
    Print ISSN: 1755-263X
    Electronic ISSN: 1755-263X
    Topics: Biology
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  • 54
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-03-06
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 55
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    Wiley-Blackwell
    Publication Date: 2018-03-06
    Electronic ISSN: 2054-4049
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography
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  • 56
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    Wiley-Blackwell
    Publication Date: 2018-02-17
    Description: While mowing-induced changes in plant traits and their effects on ecosystem functioning in semi-arid grassland are well studied, the relations between plant size and nutrient strategies are largely unknown. Mowing may drive the shifts of plant nutrient limitation and allocation. Here, we evaluated the changes in nutrient stoichiometry and allocation with variations in sizes of Leymus chinensis , the dominant plant species in Inner Mongolia grassland, to various mowing frequencies in a 17-yr controlled experiment. Affected by mowing, the concentrations of nitrogen (N), phosphorus (P), and carbon (C) in leaves and stems were significantly increased, negatively correlating with plant sizes. Moreover, we found significant trade-offs between the concentrations and accumulation of N, P, and C in plant tissues. The N:P ratios of L. chinensis aboveground biomass, linearly correlating with plant size, significantly decreased with increased mowing frequencies. The ratios of C:N and C:P of L. chinensis individuals were positively correlated with plant size, showing an exponential pattern. With increased mowing frequencies, L. chinensis size was correlated with the allocation ratios of leaves to stems of N, P, and C by the tendencies of negative parabola, positive, and negative linear. The results of structure equation modeling showed that the N, P, and C allocations were co-regulated by biomass allocation and nutrient concentration ratios of leaves to stems. In summary, we found a significant decoupling effect between plant traits and nutrient strategies along mowing frequencies. Our results reveal a mechanism for how long-term mowing-induced changes in concentrations, accumulations, ecological stoichiometry, and allocations of key elements are mediated by the variations in plant sizes of perennial rhizome grass. We evaluated the changes in nutrient stoichiometry and allocation with variations in sizes of Leymus chinensis , the dominant plant species in Inner Mongolia grassland, to various mowing frequencies in a 17-yr controlled experiment. The ratios of C:N and C:P of L. chinensis individuals were positively correlated with plant size, showing an exponential pattern. The N, P, and C allocations were co-regulated by biomass allocation and nutrient concentration ratios of leaves to stems. We found a significant decoupling effect between plant traits and nutrient strategies along mowing frequencies.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 57
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-02-16
    Description: Taraxacum kok-saghyz (TK) is a species of dandelion that is of interest commercially for the high-quality rubber produced in its roots; however, TK competes poorly with weeds. In order to overcome this shortcoming, there is interest in developing herbicide-resistant TK germplasm by a variety of means, including selection, transgene insertion, and gene editing. The potential release of such germplasm raises the question of gene flow between TK and its ubiquitous weedy relative, the common dandelion, Taraxacum officinale (TO). The potential for introgression may be influenced by the reproductive biology of TO, which can exist as a diploid sexual or polyploid obligate apomict. In North America, only polyploid, apomictic TO has been described. As weedy TO types exhibit obligate apomixis, they are expected to be unreceptive to TK pollen; however, it may still be possible for them to pollinate TK. To this end, unidirectional crosses were conducted and progeny were evaluated with molecular markers. Taraxacum officinale pollen used to fertilize TK flowers produced low seed set and seeds with a low germination rate. However, 23% of rare viable progeny proved to be the result of true hybridization. Outdoor TK seed production areas heavily contaminated with TO were also screened for naturally occurring hybridization during a three-year period using a combined strategy of both phenotyping (~3.35 million plants) and genotyping. Hybrids were detected during one of these years, at a rate of 1 in 100,000, when pollination was augmented with beehives. Hybrids from controlled crosses exhibited TO characteristics, such as lacerate leaves and apomixis. Some apomictic hybrids were able to produce viable seeds, whereas non-apomicts were sterile. Seeds produced by apomictic hybrids demonstrated the ability to establish and produce apomictic progeny when in competition with perennial ryegrass. The prevalence of apomixis in TO may limit subsequent pollen-mediated gene flow and introgression, but more work is needed to understand the longevity of apomictic hybrids under natural conditions.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 58
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    Wiley-Blackwell
    Publication Date: 2018-02-17
    Description: Anthocyanin pigments have become a model trait for evolutionary ecology as they often provide adaptive benefits for plants. Anthocyanins have been traditionally quantified biochemically or more recently using spectral reflectance. However, both methods require destructive sampling and can be labor intensive and challenging with small samples. Recent advances in digital photography and image processing make it the method of choice for measuring color in the wild. Here, we use digital images as a quick, noninvasive method to estimate relative anthocyanin concentrations in species exhibiting color variation. Using a consumer-level digital camera and a free image processing toolbox, we extracted RGB values from digital images to generate color indices. We tested petals, stems, pedicels, and calyces of six species, which contain different types of anthocyanin pigments and exhibit different pigmentation patterns. Color indices were assessed by their correlation to biochemically determined anthocyanin concentrations. For comparison, we also calculated color indices from spectral reflectance and tested the correlation with anthocyanin concentration. Indices perform differently depending on the nature of the color variation. For both digital images and spectral reflectance, the most accurate estimates of anthocyanin concentration emerge from anthocyanin content-chroma ratio, anthocyanin content-chroma basic, and strength of green indices. Color indices derived from both digital images and spectral reflectance strongly correlate with biochemically determined anthocyanin concentration; however, the estimates from digital images performed better than spectral reflectance in terms of r 2 and normalized root-mean-square error. This was particularly noticeable in a species with striped petals, but in the case of striped calyces, both methods showed a comparable relationship with anthocyanin concentration. Using digital images brings new opportunities to accurately quantify the anthocyanin concentrations in both floral and vegetative tissues. This method is efficient, completely noninvasive, applicable to both uniform and patterned color, and works with samples of any size. We use digital images as a quick, noninvasive method to estimate relative anthocyanin concentration in vegetative and reproductive plant tissues. This method is efficient, completely noninvasive, and applicable to both uniform and patterned color.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 59
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    Wiley-Blackwell
    Publication Date: 2018-02-17
    Description: Suboptimal environmental conditions are ubiquitous in nature and commonly drive the outcome of biological interactions in community processes. Despite the importance of biological interactions for community processes, knowledge on how species interactions are affected by a limiting resource, for example, low food availability, remains limited. Here, we tested whether variation in food supply causes nonadditive consumption patterns, using the macroinvertebrate community of intertidal sandy beaches as a model system. We quantified isotopically labeled diatom consumption by three macroinvertebrate species ( Bathyporeia pilosa , Haustorius arenarius, and Scolelepis squamata ) kept in mesocosms in either monoculture or a three-species community at a range of diatom densities. Our results show that B. pilosa was the most successful competitor in terms of consumption at both high and low diatom density, while H. arenarius and especially S. squamata consumed less in a community than in their respective monocultures. Nonadditive effects on consumption in this macroinvertebrate community were present and larger than mere additive effects, and similar across diatom densities. The underlying species interactions, however, did change with diatom density. Complementarity effects related to niche-partitioning were the main driver of the net diversity effect on consumption, with a slightly increasing contribution of selection effects related to competition with decreasing diatom density. For the first time, we showed that nonadditive effects of consumption are independent of food availability in a macroinvertebrate community. This suggests that, in communities with functionally different, and thus complementary, species, nonadditive effects can arise even when food availability is low. Hence, at a range of environmental conditions, species interactions hold important potential to alter ecosystem functioning. To test whether variation in food supply causes nonadditive consumption patterns, we quantified isotopically labeled diatom consumption by three intertidal macroinvertebrate species kept in mesocosms in either monoculture or a community at a range of diatom densities. Complementarity effects on consumption were the main driver of the net diversity effect, with a slightly increasing contribution of selection effects with decreasing diatom density. For the first time, we have shown that nonadditive effects of consumption are independent from food availability in a macroinvertebrate community.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 60
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    Wiley-Blackwell
    Publication Date: 2018-02-17
    Description: The purpose of this study was to determine whether limited occurrence data for highly threatened species can provide useful spatial information to inform conservation. The study was conducted across central and southern China. We developed a habitat suitability model for the Critically Endangered Chinese giant salamander ( Andrias davidianus ) based on one biotic and three abiotic parameters from single-site locality records, which represent the only relevant environmental data available for this species. We then validated model quality by testing whether increased percentage of predicted suitable habitat at the county level correlated with independent data on giant salamander presence. We randomly selected 48 counties containing historical records which were distinct from, and independent of, the single-site records used to develop the model, and 47 additional counties containing 〉50% predicted suitable habitat. We interviewed 2,812 respondents near potential giant salamander habitat across these counties and tested for differences in respondent giant salamander reports between counties selected using each method. Our model predicts that suitable giant salamander habitat is found widely across central and southern China, with counties containing ≥50% predicted suitable habitat distributed in 13 provinces. Counties with historical records contain significantly more predicted suitable habitat than counties without historical records. There are no statistical differences in any patterns of respondent giant salamander reports in surveyed counties selected from our model compared with the areas of known historical giant salamander distribution. A Chinese giant salamander habitat suitability model with strong predictive power can be derived from the restricted range of environmental variables associated with limited available presence-only occurrence records, constituting a cost-effective strategy to guide spatial allocation of conservation planning. Few reported sightings were recent, however, with most being over 20 years old, so that identification of areas of suitable habitat does not necessarily indicate continued survival of the species at these locations. To determine whether limited occurrence data can provide useful spatial information to inform conservation, we used one biotic and three abiotic parameters from single-site locality records to develop a habitat suitability model for the Critically Endangered Chinese giant salamander ( Andrias davidianus ). We then validated our model by testing whether increased percentage of predicted suitable habitat at the county level correlated with independent data on giant salamander presence. The accuracy of our habitat suitability model was supported by a close statistical congruence with the pattern and timing of giant salamander reports made by local respondents across surveyed counties with known historical records of the species, showing that a restricted range of environmental correlates derived from a limited sample of presence-only occurrence records can, at least in some cases, be used to develop robust models with strong predictive power.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 61
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    Wiley-Blackwell
    Publication Date: 2018-02-18
    Electronic ISSN: 1942-2466
    Topics: Geography , Geosciences
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  • 62
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    Wiley-Blackwell
    Publication Date: 2018-02-18
    Description: No abstract is available for this article.
    Electronic ISSN: 2333-5084
    Topics: Geosciences , Physics
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  • 63
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    Wiley-Blackwell
    Publication Date: 2018-02-18
    Description: Direct or indirect supplemental feeding of free-ranging animals occurs worldwide, resulting in significant impacts on population density or altered demographic processes. Another potential impact of increased energy intake from supplemental feeding is altered immunocompetence. As immune system maintenance is energetically costly, there may be trade-offs between immune responses and other energy-demanding physiological processes in individual animals. Although increased availability of food sources through supplemental feeding is expected to increase the overall immunocompetence of animals, empirical data verifying the association between supplemental feeding and different immune parameters are lacking. Understanding the potential influence of supplemental feeding on immune phenotypes is critical, as it may also impact host–pathogen dynamics in free-ranging animals. Using urban stray cats as a study model, we tested for associations between the intensity of supplemental feeding due to cat caretaker activity (CCA); body condition; and immune phenotype (bacterial killing assay (BKA), immunoglobulin G (IgG) concentration, and leukocyte counts). Significantly higher bacterial killing ability was observed in cats from high CCA districts, whereas higher IgG concentration and eosinophil counts were observed in cats from low CCA districts. Other leukocyte counts and body condition indices showed no significant association with CCA. We observed varying patterns of different immune components in relation to supplemental feeding. Out data suggest that supplemental feeding influences immune phenotype, not only by means of energy provisioning, but also by potentially reducing exposure rates to parasite infections through stray cat behavioral changes. Using urban stray cats as a study model, we tested for associations between the intensity of supplemental feeding due to cat caretaker activity (CCA); body condition; and immune phenotype (bacterial killing assay (BKA), immunoglobulin G (IgG) concentration, and leukocyte counts). Significantly, higher bacterial killing ability was observed in cats from high CCA districts, whereas significantly higher IgG concentration and eosinophil counts were observed in cats from low CCA districts. Out data suggest that supplemental feeding influences immune phenotype, not only by means of energy provisioning, but also by means of potentially reducing exposure rates to parasite infections through stray cat behavioral changes.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 64
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    Wiley-Blackwell
    Publication Date: 2018-02-20
    Description: Insects are often chemically defended against predators. There is considerable evidence for a group-beneficial element to their defenses, and an associated potential for individuals to curtail their own investment in costly defense while benefitting from the investments of others, termed “automimicry.” Although females in chemically defended taxa often lay their eggs in clusters, leading to siblings living in close proximity, current models of automimicry have neglected kin-selection effects, which may be expected to curb the evolution of such selfishness. Here, we develop a general theory of automimicry that explicitly incorporates kin selection. We investigate how female promiscuity modulates intragroup and intragenomic conflicts overinvestment into chemical defense, finding that individuals are favored to invest less than is optimal for their group, and that maternal-origin genes favor greater investment than do paternal-origin genes. We translate these conflicts into readily testable predictions concerning gene expression patterns and the phenotypic consequences of genomic perturbations, and discuss how our results may inform gene discovery in relation to economically important agricultural products. Insects are often chemically defended against predators. Although females in such taxa often lay their eggs in clusters, leading to siblings living in close proximity, current models have neglected kin-selection effects. Here, we investigate how female promiscuity modulates intragroup and intragenomic conflicts over investment into chemical defense, and translate these conflicts into testable predictions concerning patterns of genomic imprinting.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 65
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    Wiley-Blackwell
    Publication Date: 2018-02-20
    Description: While the effects of carcass decomposition on microorganisms have been demonstrated in recent years, little is known of how this impacts necrophagous insects. A common assumption is that insects that exploit carcasses are exposed to a high density of potentially harmful microorganisms, but no field data have so far validated this. Necrophagous beetles such as the Scarabaeinae have complex nesting behaviors with elaborate parental care. So here, we begin to explore whether this conjunction of life history and nesting behavior represents an adaptive response to the threat posed by microbes in these environments, mainly by entomopathogens. We evaluated the density and distribution of fungi and bacteria from soil near the carcasses, and their ability to infect and kill insects that are in contact with this soil during the decomposition process. Our data showed an increase in the density and activity of opportunistic or facultative pathogens during the apex of decomposition, when there is a predominance of necrophagous insects. Meanwhile, the survivorship of bait insects decreased when in contact with soil from this period of decomposition, indicating a potential risk of infection. However, the density and activity of these microorganisms decreased with distance from the carcass, mainly with depth, which would benefit tunneller beetles in particular. We have thus provided the first field data to show that necrophagous insects are indeed exposed to high densities of potentially harmful microorganisms. Furthermore, we propose that some parental care strategies may have arisen not only as a response to competition, but also as adaptations that reduce the risks of disease. Although we have focused on carrion feeders, we suggest that the same occurs with coprophagous beetles, as both carrion and dung are nutrient-rich resources. Carcasses are rich, unpredictable, and ephemeral sources of nutrients for which organisms compete, but we show for the first time that their decomposition also increases local densities of potentially harmful microorganisms, including insect pathogens. We propose that the diversity of nesting strategies among necrophagous insects is largely the result of natural selection to deal with threats from these microorganisms, rather than competition as previously understood.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 66
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    Wiley-Blackwell
    Publication Date: 2018-02-20
    Description: An organism's life history is closely interlinked with its allocation of energy between growth and reproduction at different life stages. Theoretical models have established that diminishing returns from reproductive investment promote strategies with simultaneous investment into growth and reproduction (indeterminate growth) over strategies with distinct phases of growth and reproduction (determinate growth). We extend this traditional, binary classification by showing that allocation-dependent fecundity and mortality rates allow for a large diversity of optimal allocation schedules. By analyzing a model of organisms that allocate energy between growth and reproduction, we find twelve types of optimal allocation schedules, differing qualitatively in how reproductive allocation increases with body mass. These twelve optimal allocation schedules include types with different combinations of continuous and discontinuous increase in reproduction allocation, in which phases of continuous increase can be decelerating or accelerating. We furthermore investigate how this variation influences growth curves and the expected maximum life span and body size. Our study thus reveals new links between eco-physiological constraints and life-history evolution and underscores how allocation-dependent fitness components may underlie biological diversity. Growth patterns are commonly classified as determinate or indeterminate depending on whether growth stops or continues after the onset of reproduction. It has been suggested that the latter strategy is promoted when organisms obtain diminishing returns from reproductive investments. Here, we extend this classic, binary result by demonstrating that a surprising diversity of optimal life histories may arise when varying the shapes of allocation-dependent fecundity and mortality functions. We specifically identify a system of twelve types of optimal allocation schedules, differing qualitatively in how reproductive allocation increases with body mass, and describe how they impact maximum body size and life span.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 67
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    Wiley-Blackwell
    Publication Date: 2018-02-20
    Description: Parasitoid fitness is influenced by the ability to overcome host defense strategies and by the ability of parasitoid females to select high-quality host individuals. When females are unable to differentiate among hosts, their fitness will decrease with an increasing abundance of resistant hosts. To understand the effect of mixed host populations on female fitness, it is therefore necessary to investigate the ability of female parasitoids to select among hosts. Here, we used behavioral assays, headspace volatile collection, and electrophysiology to study the ability of Asecodes parviclava to use olfactory cues to select between a susceptible host ( Galerucella calmariensis ) and a resistant host ( Galerucella pusilla ) from a distance. Our studies show that parasitoid females have the capacity to distinguish the two hosts and that the selection behavior is acquired through experiences during earlier life stages. Further, we identified two volatiles (α-terpinolene and [ E ]-β-ocimene) which amounts differ between the two plant–herbivore systems and that caused behavioral and electrophysiological responses. The consequence of this selection behavior is that females have the capacity to avoid laying eggs in G. pusilla , where the egg mortality is higher due to much stronger immune responses toward A. parviclava than in larvae of G .  calmariensis . Parasitoid fitness is influenced by the ability to overcome host defence strategies and by the ability of parasitoid females to select high quality host individuals. Here, we used behavioural assays, headspace volatile collection and electrophysiology to study the ability of Asecodes parviclava to use olfactory cues to select between a susceptible host ( Galerucella calmariensis ) and a resistant host ( Galerucella pusilla ) from a distance. Our studies show that parasitoid females have the capacity to separate the two hosts and that the selection behaviour is acquired through experiences during earlier life stages.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 68
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    Wiley-Blackwell
    Publication Date: 2018-02-20
    Description: Global consumption of crops with a yield that is dependent on animal pollinators is growing, with greater areas planted each year. However, the floral traits that influence pollinator visitation are not usually the focus of breeding programmes, and therefore, it is likely that yield improvements may be made by optimizing floral traits to enhance pollinator visitation rates. We investigated the variation present in the floral reward of the bee-pollinated crop Vicia faba (field bean). We examined the genetic potential for breeding flowers with a greater reward into current commercial varieties and used bee behavioral experiments to gain insight into the optimal nectar concentration to maximize bee preference. There was a large range of variation in the amount of pollen and nectar reward of flowers in the genotypes investigated. Bee behavioral experiments using nectar sugar concentrations found in V. faba lines suggest that Bombus terrestris prefers 55% w/w sugar solution over 40% w/w, but has no preference between 55% w/w and 68% w/w sugar solution. We provide a first indication of the force required to open V. faba flowers. Our results provide a valuable starting point toward breeding for varieties with optimized floral reward. Field studies are now needed to verify whether the genetic potential for breeding more rewarding flowers can translate into higher yield and yield stability. This study examines heritable variation in, and pollinator response to, key flower reward traits of an important legume crop. These traits represent potential targets for breeding to improve crop yield by enhancing pollinator visitation and to support pollinator populations in agricultural areas.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 69
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    Wiley-Blackwell
    Publication Date: 2018-02-20
    Description: Domestication is a type of experimental evolution in which humans have artificially selected for specific desired traits. Selected strain animals can be utilized to identify correlated responses by comparing them to the wild strain. In particular, domestic turkeys have been selected for increased body mass and high-growth rate, most significantly over the past 60 years. Yet it remains unclear how artificial selection has affected the morphology and evolution of the musculoskeletal system as a whole. Here, we compare growth rate over 21 weeks, hind limb bone scaling across ontogeny via in vivo CT scanning, and muscle proportions in wild and domestic turkeys to identify differences in structural scaling and the potential contributions of selection and developmental plasticity to whole-organism morphology. The domestic turkeys grew at a higher rate (0.14 kg/day vs. 0.05 kg/day) and reached over 3 times the body mass of wild birds. Comparing the proportional muscle masses in adult turkeys, only the trunk had a greater mass ratio in the domestic turkey, driven solely by M. pectoralis (2.8 times larger). The proportional increase in only breast meat and no other muscles highlights the surgical precision attainable with artificial selection. The domestic turkey femur and tibiotarsus displayed increases in polar moment of area, apparently maintaining torsional strength as body mass increased. The lack of dimensional change in the more vertically held tarsometatarsus is consistent with the pattern expected due to developmental plasticity. These results from the domestic turkey emphasize that there are morphological limits to preserving the balance between growth and function, and varying rates of trait evolution can further complicate this equilibrium. Artificial selection has resulted in domestic turkeys that are three times the body mass of wild turkeys, an interesting example of experimental evolution. While most muscles increase in mass, the pectoralis muscle is a greater proportion of the overall body mass in the domestic birds, highlighting the precision of selection. While the hind limb bones do not increase much in length, dimensional changes maintain torsional strength, likely due to developmental plasticity.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 70
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    Wiley-Blackwell
    Publication Date: 2018-02-18
    Description: Intraspecific aggression represents a major source of mortality for many animals and is often experienced alongside the threat of predation. The presence of predators can strongly influence ecological systems both directly by consuming prey and indirectly by altering prey behavior or habitat use. As such, the threat of attack by higher level predators may strongly influence agonistic interactions among conspecifics via nonconsumptive (e.g., behaviorally mediated) predator effects. We sought to investigate these interactions experimentally using larval salamanders ( Ambystoma maculatum ) as prey and dragonfly nymphs ( Anax junius ) as predators. Specifically, we quantified salamander behavioral responses to perceived predation risk (PPR) from dragonfly nymphs and determined the degree to which PPR influenced intraspecific aggression (i.e., intraspecific biting and cannibalism) among prey. This included examining the effects of predator exposure on the magnitude of intraspecific biting (i.e., extent of tail damage) and the resulting change in performance (i.e., burst swim speed). Salamander larvae responded to PPR by reducing activity and feeding, but did not increase refuge use. Predator exposure did not significantly influence overall survival; however, the pattern of survival differed among treatments. Larvae exposed to PPR experienced less tail damage from conspecifics, and maximum burst swim speed declined as tail damage became more extensive. Thus, escape ability was more strongly compromised by intraspecific aggression occurring in the absence of predation risk. We conclude that multitrophic indirect effects may importantly modulate intraspecific aggression and should be considered when evaluating the effects of intraspecific competition. Using a dragonfly nymph (predator)–salamander larvae (prey) system, we experimentally investigate the effect of perceived predation risk on the extent of intraspecific aggression among prey. Larval salamander activity, feeding behavior, and the extent of tail damage from conspecifics were reduced by exposure to predator-treated water. We conclude that multitrophic indirect effects may importantly modulate intraspecific aggression and should be considered when evaluating the effects of intraspecific competition.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 71
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-02-22
    Description: Biological nitrogen (N 2 ) fixation is one of the main sources of available N for pristine ecosystems such as subarctic and arctic tundra. Although this has been acknowledged more than a decade ago, few attempts have been undertaken to identify the foremost driver of N 2 fixation in the high Arctic. Here, we report results from in situ measurements of N 2 fixation throughout the main growing period (June–August) in high arctic tundra, Greenland, in climate change treatments, shading and warming, and control. Nitrogen fixation was also measured in cores that received additional water prior to the measurements. The climate change field treatments did not lead to significant changes in any measured parameters; however, N 2 fixation was promoted by adding water, and moisture was the most important factor influencing N 2 fixation in all climate change field treatments. Maximum N 2 fixation rates were measured below 14°C soil temperature, which is much lower than the theoretical and previously reported temperature optimum for the nitrogenase enzyme. Diazotroph (N 2 fixing bacteria) communities are adapted to low temperatures in high arctic settings, and increased temperature in a future climate may lead to decreased N 2 fixation rates, or to a shift in diazotroph communities.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 72
    Publication Date: 2018-02-16
    Description: Urban ecosystems are widely hypothesized to be more ecologically homogeneous than natural ecosystems. We argue that urban plant communities assemble from a complex mix of horticultural and regional species pools, and evaluate the homogenization hypothesis by comparing cultivated and spontaneously occurring urban vegetation to natural area vegetation across seven major U.S. cities. There was limited support for homogenization of urban diversity , as the cultivated and spontaneous yard flora had greater numbers of species than natural areas, and cultivated phylogenetic diversity was also greater. However, urban yards showed evidence of homogenization of composition and structure . Yards were compositionally more similar across regions than were natural areas, and tree density was less variable in yards than in comparable natural areas. This homogenization of biodiversity likely reflects similar horticultural source pools, homeowner preferences, and management practices across U.S. cities.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 73
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    Wiley-Blackwell
    Publication Date: 2018-02-24
    Description: There is little direct evidence for effects of soil heterogeneity and root plasticity on the competitive interactions among plants. In this study, we experimentally examined the impacts of temporal nutrient heterogeneity on root growth and interactions between two plant species with very different rooting strategies: Liquidambar styraciflua (sweet gum), which shows high root plasticity in response to soil nutrient heterogeneity, and Pinus taeda (loblolly pine), a species with less plastic roots. Seedlings of the two species were grown in sandboxes in inter- and intraspecific combinations. Nutrients were applied in a patch either in a stable (slow-release) or in a variable (pulse) manner. Plant aboveground biomass, fine root mass, root allocation between nutrient patch and outside the patch, and root vertical distribution were measured. L. styraciflua grew more aboveground (40% and 27% in stable and variable nutrient treatment, respectively) and fine roots (41% and 8% in stable and variable nutrient treatment, respectively) when competing with P. taeda than when competing with a conspecific individual, but the growth of P. taeda was not changed by competition from L. styraciflua . Temporal variation in patch nutrient level had little effect on the species’ competitive interactions. The more flexible L. styraciflua changed its vertical distribution of fine roots in response to competition from P. taeda , growing more roots in deeper soil layers compared to its roots in conspecific competition, leading to niche differentiation between the species, while the fine root distribution of P. taeda remained unchanged across all treatments. Synthesis . L. styraciflua showed greater flexibility in root growth by changing its root vertical distribution and occupying space of not occupied by P. taeda . This flexibility gave L. styraciflua an advantage in interspecific competition. Liquidambar styraciflua showed greater flexibility in root growth by changing its root vertical distribution and occupying space not occupied by Pinus taeda . This flexibility gave L. styraciflua an advantage in interspecific competition.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 74
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    Wiley-Blackwell
    Publication Date: 2018-02-24
    Description: Animal signals are inherently complex phenotypes with many interacting parts combining to elicit responses from receivers. The pattern of interrelationships between signal components reflects the extent to which each component is expressed, and responds to selection, either in concert with or independently of others. Furthermore, many species have complex repertoires consisting of multiple signal types used in different contexts, and common morphological and physiological constraints may result in interrelationships extending across the multiple signals in species’ repertoires. The evolutionary significance of interrelationships between signal traits can be explored within the framework of phenotypic integration, which offers a suite of quantitative techniques to characterize complex phenotypes. In particular, these techniques allow for the assessment of modularity and integration, which describe, respectively, the extent to which sets of traits covary either independently or jointly. Although signal and repertoire complexity are thought to be major drivers of diversification and social evolution, few studies have explicitly measured the phenotypic integration of signals to investigate the evolution of diverse communication systems. We applied methods from phenotypic integration studies to quantify integration in the two primary vocalization types (advertisement and aggressive calls) in the treefrogs Hyla versicolor , Hyla cinerea, and Dendropsophus ebraccatus . We recorded male calls and calculated standardized phenotypic variance–covariance ( P ) matrices for characteristics within and across call types. We found significant integration across call types, but the strength of integration varied by species and corresponded with the acoustic similarity of the call types within each species. H. versicolor had the most modular advertisement and aggressive calls and the least acoustically similar call types. Additionally, P was robust to changing social competition levels in H. versicolor . Our findings suggest new directions in animal communication research in which the complex relationships among the traits of multiple signals are a key consideration for understanding signal evolution. Signals, such as body parts, are complex structures that must be integrated to function properly, yet this integration also may limit the independent evolution of signal traits. We investigated how different signal traits were integrated across the repertoires of three treefrog species and found evidence for variation between species in the strength of integration that seemed to correspond with the similarity of different signal types.
    Electronic ISSN: 2045-7758
    Topics: Biology
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  • 75
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-02-24
    Description: Migratory ungulates are often exposed to anthropogenic infrastructure along their migration routes. Understanding the influence of such development on migratory behavior is critical to successful planning and conservation. Impermeable barriers have obvious and detrimental effects to migratory ungulate populations, but the influence of semi-permeable barriers, where the connectivity of migration habitat is maintained but the migration routes are compromised by anthropogenic development, remains unclear. We evaluated the influence of development on the migratory behavior of individual mule deer ( Odocoileus hemionus ) in western Wyoming, USA. We used fine-scale movement data to evaluate the influence of anthropogenic infrastructure on deer movement rates, stopover use, and fidelity to migration routes for individual animals across multiple seasons and years. Deer avoided human infrastructure when selecting stopover sites. Fidelity to migration routes and stopover areas, as measured by the degree of spatial overlap between years, was not influenced by development, except in one heavily developed area. Our results suggested that deer increased rate of movement, reduced time in stopovers, and shifted stopovers in areas of intense development. In most cases, deer maintained fidelity to migration routes, regardless of development, suggesting that deer mediated exposure to development by altering movement—rates and timing—rather than the routes they traversed. This work adds to a growing number of studies indicating that development can disrupt migratory behavior. Understanding how different types and intensities of development influence migration can help inform land-use planning and conservation of migratory ungulates.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 76
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    Wiley-Blackwell
    Publication Date: 2018-02-24
    Description: Sibling cannibalism—the killing and consumption of conspecifics within broods—carries a high risk of direct and inclusive fitness loss for parents and offspring. We reported previously that a unique vibrational behavior shown by the mother of the subsocial burrower bug, Adomerus rotundus (Heteroptera: Cydnidae), induced synchronous hatching. Maternal regulation may be one of the most effective mechanisms for preventing or limiting sibling cannibalism. Here, we tested the hypothesis that synchronous hatching induced by maternal vibration in A. rotundus prevents sibling cannibalism. Mothers and their mature egg masses were allocated to three groups: synchronous hatching by maternal vibration (SHmv), synchronous hatching by artificial vibration (SHav), and asynchronous hatching (AH). We then investigated the influence of each hatching strategy on the occurrence of sibling cannibalism of eggs and early-instar nymphs in the laboratory. No difference in the proportion of eggs cannibalized was observed among the three groups. However, the proportion of nymphs cannibalized was higher in the AH group than in the SHmv group. The difference in the number of days to first molting within clutch was significantly higher in the AH group than in the SHmv group. Junior nymphs were sometimes eaten by senior nymphs. However, immediately after molting, senior nymphs were at a high risk of being eaten by junior nymphs. Our results indicate that synchronous hatching of A .  rotundus is necessary to mitigate the risk of sibling cannibalism. Mother subsocial burrower bugs ( Adomerus rotundus ) use a unique vibrational behavior to induce synchronous hatching. We found that conditions lacking maternal hatching regulation facilitated asynchronous hatching and asynchronous molting and increased sibling cannibalism within a brood. Our results provide experimental evidence that synchronous hatching regulated by mother mitigates the risk of sibling cannibalism.
    Electronic ISSN: 2045-7758
    Topics: Biology
    Published by Wiley-Blackwell
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  • 77
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    Wiley-Blackwell
    In: Ecosphere
    Publication Date: 2018-02-24
    Description: Arctic vegetation phenology is a sensitive indicator of a changing climate, and rapid assessment of vegetation status is necessary to more comprehensively understand the impacts on foliar condition and photosynthetic activity. Airborne and space-borne optical remote sensing has been successfully used to monitor vegetation phenology in Arctic ecosystems by exploiting the biophysical and biochemical changes associated with vegetation growth and senescence. However, persistent cloud cover and low sun angles in the region make the acquisition of high-quality temporal optical data within one growing season challenging. In the following study, we examine the capability of “near-field” remote sensing technologies, in this case digital, true-color cameras to produce surrogate in situ spectral data to characterize changes in vegetation driven by seasonal pigment dynamics. Simple linear regression was used to investigate relationships between common pigment-driven spectral indices calculated from field-based spectrometry and red, green, and blue (RGB) indices from corresponding digital photographs in three dominant vegetation communities across three major seasons at Toolik Lake, North Slope, Alaska. We chose the strongest and most consistent RGB index across all communities to represent each spectral index. Next, linear regressions were used to relate RGB indices and extracted leaf-level pigment content with a simple additive error propagation of the root mean square error. Results indicate that the green-based RGB indices had the strongest relationship with chlorophyll a and total chlorophyll, while a red-based RGB index showed moderate relationships with the chlorophyll to carotenoid ratio. The results suggest that vegetation color contributes strongly to the response of pigment-driven spectral indices and RGB data can act as a surrogate to track seasonal vegetation change associated with pigment development and degradation. Overall, we find that low-cost, easy-to-use digital cameras can monitor vegetation status and changes related to seasonal foliar condition and photosynthetic activity in three dominant, low-Arctic vegetation communities.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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