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2,395 results for “Contrast”
Data from: Climate limitation at the cold edge – contrasting perspectives from species distribution modelling and a transplant experiment
<p>The role of climate in determining range margins is often studied using species distribution models (SDMs), which are easily applied but have well-known limitations, e.g. due to their correlative nature and colonization and extinction time lags. Transplant experiments can give more direct information on environmental effects, but often cover small spatial and temporal scales. We simultaneously applied an SDM using high-resolution spatial predictors and an integral projection (demographic) model based on a transplant experiment at 58 sites to examine the effects of microclimate, light and soil conditions on the distribution and performance of a forest herb, <i>Lathyrus vernus</i>, at its cold range margin in central Sweden. In the SDM, occurrences were strongly associated with warmer climates. In contrast, only weak effects of climate were detected in the transplant experiment, whereas effects of soil conditions and light dominated. The higher contribution of climate in the SDM is likely a result from its correlation with soil quality, forest type, and potentially historic land use, which were unaccounted for in the model. Predicted habitat suitability and population growth rate, yielded by the two approaches, were not correlated across the transplant sites. We argue that the ranking of site habitat suitability is probably more reliable in the transplant experiment than in the SDM because predictors in the former better describe understory conditions, but that ranking might vary among years, e.g. due to differences in climate. Our results suggest that <i>L. vernus</i> is limited by soil and light rather than directly by climate at its northern range edge, where conifers dominate forests and create suboptimal conditions of soil and canopy-penetrating light. A general implication of our study is that to better understand how climate change influences range dynamics, we should not only strive to improve existing approaches but also to use multiple approaches in concert.</p>
Contrasting association of Leptin receptor polymorphisms and haplotypes with polycystic ovary syndrome in Bahraini and Tunisian women: a case–control study
<p><span><b>Background</b>. This study examined the contribution of ethnicity to the association of leptin receptor gene (<i>LEPR)</i> genetic variants with polycystic ovary syndrome (PCOS) in Tunisian and Bahraini Arabic-speaking women.<b> </b></span></p> <p><span><b>Methods. </b>Subjects consisted of 320 women with PCOS, and 446 eumenorrhic women from Tunisia, and 242 women with PCOS and 238 controls from Bahrain. Genotyping of (exonic) rs1137100 and rs1137101 and (intronic) rs2025804 <i>LEPR</i> variants was done by allelic exclusion.<b> </b></span></p> <p><span><b>Results. </b>The minor allele frequencies of rs1137100 and rs1137101 were significantly different between PCOS cases and control women from Bahrain but not Tunisia, and <i>LEPR</i> rs1137101 was associated with increased PCOS susceptibility only in Bahraini subjects. Furthermore, rs1137100 was associated with decreased PCOS risk among Bahrainis under codominant and recessive models; rs1137100 was negatively associated with PCOS in Tunisians after controlling for testosterone. In addition, rs2025804 was associated with increased PCOS risk among Tunisian but not Bahraini women, after adjusting for key covariates. Negative correlation was seen between rs1137101 and triglycerides in Tunisians, while HOMA-IR and insulin correlated with rs2025804 and rs1137101 among Bahraini subjects, and rs1137101 correlated with estradiol and prolactin. Taking TAG haplotype as common, positive association of TAA and negative association of TGG haplotype with PCOS was seen among Bahraini women; no three-locus PCOS-associated haplotypes were found in Tunisians.<b> </b></span></p> <p><span><b>Conclusions. </b>T<span>his study is the first to demonstrate the contribution of ethnicity to the association of <i>LEPR</i> gene variants with PCOS</span>, thereby highlighting the significance of controlling for ethnicity in gene association investigations.</span></p>
Contrasting responses to climate change at Himalayan treelines revealed by population demographics of two dominant species
<ol> <li><span>Alpine treelines are expected to shift upward due to recent climate change. However, interpretation of changes in montane systems has been problematic because effects of climate change are frequently confounded with those of land use changes. The eastern Himalaya, particularly Langtang National Park, Central Nepal, has been relatively undisturbed for centuries and thus presents an opportunity for studying climate change impacts on alpine treeline uncontaminated by potential confounding factors.</span></li> <li><span>We studied two dominant species, <i>Abies spectabilis </i>and <i>Rhododendron campanulatum</i>, above and below the treeline on two mountains. We constructed 13 transects, each spanning up to 400m in elevation, in which we recorded height and state (dead or alive) of all trees, as well as slope, aspect, canopy density, and measures of anthropogenic and animal disturbance. In a subset of individuals, we determined the age of the plants with tree rings.</span></li> <li>All size classes of <i>R. campanulatum</i> plants had lower mortality above treeline than below it, and young <i>R. campanulatum</i> plants (<2m tall) were at higher density above treeline than below. <i>A. spectabilis</i> shows little evidence of a position change from the historic treeline, with a sudden extreme drop in density above treeline compared to below. Recruitment, as measured by size class distribution, was greater above treeline than below for both species but <i>A. spectabilis</i> is confined to ~25m above treeline whereas <i>R. campanulatum</i> is luxuriantly growing up to 200m above treeline. </li> <li> <i>Synthesis.</i> Evidence suggests that the elevational limits of <i>R. campanulatum</i> have shifted upward both because (1) young <i>R. campanulatum</i> plants above treeline benefited from facilitation of recruitment by surrounding vegetation, allowing upward expansion of recruitment, and (2) increased adult survival due to a general temperature amelioration to mature plants. We predict that the current pure stand of <i>R. campanulatum</i> growing above treeline will be colonized by <i>A. spectabilis</i> that will, in turn, outshade and eventually relegate <i>R. campanulatum </i>to be a minor component of the community, as is the current situation below the treeline. </li> </ol>
Phase-contrast CT of BDL rats liver-2 week
<p>Datasets of paper "Insight into ductular reaction in obstructive biliary disease from a three-dimensional perspective using ex vivo PCCT"</p>
Precipitation regime controls bryosphere carbon cycling similarly across contrasting ecosystems
<p>In arctic and boreal ecosystems, ground bryophytes play an important role in regulating carbon (C) exchange between vast belowground C stores and the atmosphere. Climate is changing particularly fast in these high-latitude regions, but it is unclear how altered precipitation regimes will affect C dynamics in the bryosphere (i.e., the ground moss layer including senesced moss, litter, and associated biota) and the closely associated upper humus layer, and how these effects will vary across contrasting environmental conditions. Here, we set up a greenhouse experiment in which mesocosms were assembled containing samples of the bryosphere, dominated by the feather moss <i>Hylocomium splendens</i>, and the upper humus layer, that were collected from across a boreal forest chronosequence in northern Sweden which varies strongly in nutrient availability, productivity, and soil biota. We tested the effect of variation in precipitation volume and frequency on CO<sub>2</sub> exchange and dissolved organic carbon (DOC) export, and on moss growth. As expected, reduced precipitation volume and frequency lowered net CO<sub>2</sub> efflux, DOC export, and moss growth. However, by regulating moisture, the lower bryosphere and humus layers often mediated how precipitation volume and frequency interacted to drive C dynamics. For example, less frequent precipitation reduced moss growth only when precipitation volume was low. When volume was high, high moisture content of the humus layer helped avoid moss desiccation. Variation in precipitation regime affected C cycling consistently in samples collected across the chronosequence, despite large environmental variation along the sequence. This suggests that the bryosphere exerts a strong buffering effect on environmental variation at the forest floor, which leads to similar responses of C cycling to external perturbations across highly contrasting ecosystems. As such, our study indicates that projected increases in droughts and ground evapotranspiration in high-latitude regions resulting from climate change will consistently reduce C losses from moss-dominated ecosystems.</p>
Contrasting latitudinal patterns in diversity and stability in a high-latitude species-rich moth community
<p>Aim: Biodiversity is currently undergoing rapid restructuring across the globe. However, the nature of biodiversity change is not well understood, as community-level changes may hide differential responses in individual population trajectories. Here, we quantify spatio-temporal community and stability dynamics using a long-term high-quality moth monitoring dataset. Location: Finland, Northern Europe. Time period: 1993-2012. Major taxa studied: Nocturnal moths (Lepidoptera). Methods: We quantify patterns of change in species richness, total abundance, dominance and temporal variability at different organisational levels over a 20-year period and along a 1100-km latitudinal gradient. We used mixed-effects and linear models to quantify temporal trends for the different community and stability metrics and to test for latitudinal (or longitudinal) effects. Results: We find contrasting patterns for different community metrics, and strong latitudinal patterns. While total moth abundance has declined, species richness has simultaneously increased over the study period, but with rates accelerating with latitude. Additionally, we reveal a latitudinal pattern in temporal variability – the northernmost locations exhibited higher variability over time, as quantified by both metrics of richness and aggregated species populations trends. Main Conclusions: When combined, our findings likely reflect an influx of species expanding their ranges poleward in response to warming. The overall decline in abundance and the latitudinal effect on temporal variability highlight potentially severe consequences of global change for community structure and integrity across high-latitude regions. Importantly, our results underscore that increases in species richness may be paralleled by a loss of individuals, which in turn might affect higher trophic levels. Our findings suggest that the ongoing global species redistribution is affecting both community structure and stability over time, leading to compounded and partly opposing effects of global change depending on what biodiversity dimension we focus on.</p>
Data from: Contrasting patterns of leaf trait variation among and within species during tropical dry forest succession in Costa Rica
A coordinated response to environmental drivers amongst individual functional traits is central to the plant strategy concept. However, whether the trait co-ordination observed at the global scale occurs at other ecological scales (especially within species) remains an open question. Here, for sapling communities of two tropical dry forest types in Costa Rica, we show large differences amongst traits in the relative contribution of species turnover and intraspecific variation to their directional changes in response to environmental changes along a successional gradient. We studied the response of functional traits associated with the leaf economics spectrum and drought tolerance using intensive sampling to analyse inter- and intra-specific responses to environmental changes and ontogeny. Although the overall functional composition of the sapling communities changed during succession more through species turnover than through intraspecific trait variation, their relative contributions differed greatly amongst traits. For instance, community mean specific leaf area changed mostly due to intraspecific variation. Traits of the leaf economics spectrum showed decoupled responses to environmental drivers and ontogeny. These findings emphasise how divergent ecological mechanisms combine to cause great differences in changes of individual functional traits over environmental gradients and ecological scales.
Data from: Contrasting patterns of functional diversity in coffee root fungal communities associated with organic and conventionally-managed fields
<p>The structure and function of fungal communities in the coffee rhizosphere is shaped by crop environment. Because coffee can be grown along a management continuum from conventional application of pesticides and fertilizers in full sun to organic management in a shaded understory, we used coffee fields to hold host constant while comparing rhizosphere fungal communities in markedly different environmental conditions with regard to shade and inputs. We characterized the shade and soil environment in 25 fields under conventional, organic or transitional management in two regions of Costa Rica. We amplified the ITS2 region of fungal DNA from coffee roots in these fields and characterized the rhizosphere fungal community via high-throughput sequencing. Sequences were assigned to guilds to determine differences in functional diversity and trophic structure among coffee field environments. Organic fields had more shade, a greater richness of shade tree species, more leaf litter, and were less acidic, with lower soil nitrate availability and higher soil copper, calcium, and magnesium than conventionally-managed fields, although differences between organic and conventionally-managed fields in shade, calcium and magnesium depended on region. Differences in richness and community composition of rhizosphere fungi between organic and conventionally-managed fields were also correlated with shade, soil acidity, nitrate, and copper. Trophic structure differed with coffee field management. Saprotrophs, plant pathogens, and mycoparasites were more diverse and plant pathogens were more abundant in organic than in conventionally-managed fields, while saprotroph-plant pathogens were more abundant in conventionally-managed fields. These differences reflected environmental differences and depended on region.</p> <p><b>IMPORTANCE</b></p> <p>Rhizosphere fungi play key roles in ecosystems, as nutrient cyclers, pathogens, and mutualists, yet little is currently known about which environmental factors and how agricultural management shape rhizosphere fungal communities and their functional diversity. This field study of the coffee agroecosystem suggests that organic management not only fosters a greater overall diversity of fungi, but also maintains a greater richness of saprotrophic, plant pathogenic and mycoparasitic fungi that has implications for efficiency of nutrient cycling and regulation of plant pathogen populations in agricultural systems. As well as influencing community composition and richness of rhizosphere fungi, shade management and use of fungicides and synthetic fertilizers altered the trophic structure of the coffee agroecosystem.</p>
Data for 'Phenotypic plasticity and genetic variation in leaf traits of Yushania niitakayamensis (Bambusoideae; Poaceae) in contrasting light environments'
<p>This is the Data for the article entitled 'Phenotypic plasticity and genetic variation in leaf traits of Yushania niitakayamensis (Bambusoideae; Poaceae) in contrasting light environments' submitted to 'Journal of Plant Research'</p> <p><a href="https://doi.org/10.1007/s10265-021-01327-y">https://doi.org/10.1007/s10265-021-01327-y</a></p> <p>Traits' names are listed below:</p> <p>Leaf length (LL), Leaf width (LW), Specific leaf area (SLA), Stomatal density (SD), Leaf thickness (LT), Relative frequency of cavities formed by the collapsed fusoid cells (CFC), Leaf chlorophyll content per unit area ([Chl]area), Ratio of chlorophyll a to chlorophyll b (Chl a/b), Leaf nitrogen content per unit area ([N]area), Leaf stable carbon isotope ratio (δ13C), Photosynthetic photon flux density (PPFD), Actual quantum yield of PSII electron transport (ΦPSII), Electron transport rate (ETR), Light-saturated photosynthetic rate (Asat), Stomatal conductance (gs), Dark respiration rate (Rd), Apparent quantum yield (AQY), The ratio of intercellular to ambient CO2 concentration (Ci/Ca), Photosynthetic water use efficiency (WUE)</p>
Data from: Adaptive maternal investment in the wild? Links between maternal growth trajectory and offspring size, growth, and survival in contrasting environments
Life history theory predicts that investment per offspring should correlate negatively with the quality of environment offspring are anticipated to encounter; parents may use their own experience as juveniles to predict this environment and may modulate offspring traits such as growth capacity as well as initial size. We manipulated nutrient levels in the juvenile habitat of wild Atlantic salmon Salmo salar to investigate the hypothesis that the egg size maximizing juvenile growth and survival depends on environmental quality. We also tested whether offspring traits were related to parental growth trajectory. Mothers that grew fast when young produced more, smaller offspring than mothers that had grown slowly to reach the same size. Despite their size disadvantage, offspring of faster-growing mothers grew faster than those of slow-growing mothers in all environments, counter to the expectation that they would be competitively disadvantaged. However, they had lower relative survival in environments where the density of older predatory/competitor fish was relatively high. These links between maternal (but not paternal) growth trajectory and offspring survival rate were independent of egg size, underscoring that mothers may be adjusting egg traits other than size to suit the anticipated environment faced by their offspring.
Data from: Comparative phylogeography, genetic differentiation, and contrasting reproductive modes in three fungal symbionts of a multipartite bark beetle symbiosis
Multipartite symbioses are complex symbiotic relationships involving multiple interacting partners. These types of partnerships provide excellent opportunities in which to apply a comparative approach to identify common historical patterns of population differentiation and species-specific life history traits. Using three symbiotic blue stain fungal species (Ophiostomatacea) associated with outbreaking populations of the mountain pine beetle (Dendroctonus ponderosae Hopkins) in western Canada, we applied phylogenetic, population genetic, and demographic approaches to clarify phylogeographic patterns among the three fungal species. Broadly, the three species showed significant population differentiation, forming northern and southern populations, despite dramatic differences in haplotype diversity. Finer scale structuring and population demographic patterns were less consistent, showing some interspecific incongruence. By contrasting these species simultaneously, we were able to identify differences in recombination rate and ecological traits that can explain the observed patterns of incongruence among the fungal species. By applying a comparative approach to partners of a multipartite symbiosis we were able to distinguish congruent population structuring and species-specific differences that help us to understand the complexity and evolution of this symbiotic system.
Data from: Müllerian mimicry of a quantitative trait despite contrasting levels of genomic divergence and selection
<p>Hybrid zones, where distinct populations meet and interbreed, give insight into how differences between populations are maintained despite gene flow. Studying clines in genetic loci and adaptive traits across hybrid zones is a powerful method for understanding how selection drives differentiation within a single species, but can also be used to compare parallel divergence in different species responding to a common selective pressure. Here, we study parallel divergence of wing colouration in the butterflies <i>Heliconius erato</i> and <i>H</i><i>. melpomene</i>, which are distantly related Müllerian mimics that show parallel geographic variation in both discrete variation in pigmentation, and quantitative variation in structural colour. Using geographic cline analysis, we show that clines in these traits are positioned in the roughly the same geographic region for both species, which is consistent with direct selection for mimicry. However, the width of the clines varies markedly between species. This difference is explained in part by variation in the strength of selection acting on colour traits within each species, but may also be influenced by differences in the dispersal rate and total strength of selection against hybrids between the species. Genotyping-by-sequencing also revealed weaker population structure in <i>H. melpomene</i>, suggesting the hybrid zones may have evolved differently in each species; which may also contribute to the patterns of phenotypic divergence in this system Overall, we conclude that multiple factors are needed to explain patterns of clinal variation within and between these species, although mimicry has probably played a central role.</p>
Data from: Is MHC diversity a better marker for conservation than neutral genetic diversity? a case study of two contrasting dolphin populations
Genetic diversity is essential for populations to adapt to changing environments. Measures of genetic diversity are often based on selectively neutral markers, such as microsatellites. Genetic diversity to guide conservation management, however, is better reflected by adaptive markers, including genes of the major histocompatibility complex (MHC). Our aim was to assess MHC and neutral genetic diversity in two contrasting bottlenose dolphin (Tursiops aduncus) populations in Western Australia—one apparently viable population with high reproductive output (Shark Bay) and one with lower reproductive output that was forecast to decline (Bunbury). We assessed genetic variation in the two populations by sequencing the MHC class II DQB, which encompasses the functionally important peptide binding regions (PBR). Neutral genetic diversity was assessed by genotyping twenty‐three microsatellite loci. We confirmed that MHC is an adaptive marker in both populations. Overall, the Shark Bay population exhibited greater MHC diversity than the Bunbury population—for example, it displayed greater MHC nucleotide diversity. In contrast, the difference in microsatellite diversity between the two populations was comparatively low. Our findings are consistent with the hypothesis that viable populations typically display greater genetic diversity than less viable populations. The results also suggest that MHC variation is more closely associated with population viability than neutral genetic variation. Although the inferences from our findings are limited, because we only compared two populations, our results add to a growing number of studies that highlight the usefulness of MHC as a potentially suitable genetic marker for animal conservation. The Shark Bay population, which carries greater adaptive genetic diversity than the Bunbury population, is thus likely more robust to natural or human‐induced changes to the coastal ecosystem it inhabits.
Contrasting patterns in biomass allocation, root morphology and mycorrhizal symbiosis for phosphorus acquisition among 20 chickpea genotypes with different amounts of rhizosheath carboxylates
<p>1. Adjustments in root biomass allocation, root morphology, carboxylate exudation and mycorrhizal symbiosis are well-known strategies for plants to cope with phosphorus (P) deficiency. Large genotypic variation in these functional traits has been demonstrated within numerous species. Yet, whether these functional traits are coordinated differently among genotypes of a species to enhance P acquisition remains unknown.</p> <p>2. We characterised 11 root functional traits associated with P acquisition in 20 chickpea genotypes with contrasting amounts of rhizosheath carboxylates, grown in a glasshouse with severely limiting insoluble (10 mg kg<sup>–1</sup> FePO<sub>4</sub>), moderately limiting soluble (10 mg kg<sup>–1</sup> KH<sub>2</sub>PO<sub>4</sub>), and adequate (50 mg kg<sup>–1</sup> KH<sub>2</sub>PO<sub>4</sub>) P supply.</p> <p>3. Substantial variation was found among genotypes in root functional traits associated with P acquisition. Genotypes with a large amount of carboxylates (HRC) had thinner roots, and a lower root mass fraction and root mass density, but higher specific root length and colonisation by arbuscular mycorrhizal fungi (AMF) than genotypes with a small amount of rhizosheath carboxylates.</p> <p>4. In response to soil P availability, chickpea genotypes showed large plasticity in root biomass allocation, rhizosheath pH, carboxylate amount, and colonisation by AMF, but a limited response in most root morphological traits (i.e. mean root diameter, root mass density and specific root length). Shoot P content was strongly correlated with different root functional traits in the three P treatments.</p> <p>5. Our findings suggest a range of predictable relationships between root functional traits among chickpea genotypes; those with HRC tended to have relatively thinner roots with lower cost of root construction, while allocating more resources to carboxylate exudation and colonisation by AMF. The shift in the relationships between shoot P content and root functional traits indicates that <span class="fontstyle01"><span>root traits and/or trait combinations in chickpea vary in a manner that enhances P acquisition under specific soil P conditions (i.e. P sources/ levels)</span></span>. Such knowledge provides valuable information for chickpea genotype breeding and our understanding of evolution of traits with improved root/rhizosphere functioning.</p> <p> </p>
Data from: Contrasting per-gram competitive and soil resource effects in grasses and woody plants
1. Plant species differ in their competitive effects by decreasing resource availability via uptake, but in some cases may increase resource availability via non-uptake pathways. Here we explore differences between grasses and woody plants in their competitive effects, and relate these to differences in resource effects. 2. We grew five species each of grasses and woody plants in monocultures for eight years. In the final two growing seasons, competitive effects were measured by growing transplants in all monocultures and in plots without neighbours. 3. Total competitive effects were significantly greater for woody plants than grasses. In contrast, the competitive effect per gram of grasses was about 17 times greater than that of woody plants. 4. For grasses, soil water and soil available N decreased significantly with increasing biomass. In contrast, for woody plants, soil water and soil available N increased significantly with increasing biomass. The results suggest that the intense per-gram competitive effects in grasses is related to the uptake of soil resources, and that the significantly lower per-gram competitive effects of woody plants may be related to their positive effects on soil resources. 5. Synthesis. The results link differences in competitive effects between grasses and woody plants to differences in the direction of their effects on soil resources. These differences may contribute to the entrainment of negative feedback in grasslands, excluding trees by means of strong competition, and the entrainment of positive feedback beneath woody plants establishing in grasslands, resulting in a state change from grassland to woody vegetation.
Data from: Life cycle matters: DNA barcoding reveals contrasting community structure between fern sporophytes and gametophytes
Ferns are the only major lineage of vascular plants that have nutritionally independent sporophyte (diploid) and gametophyte (haploid) life stages. However, the implications of this unique life cycle for fern community ecology have rarely been considered. To compare patterns of community structure between fern sporophytes and gametophytes, we conducted a survey of the ferns of the islands of Moorea and Tahiti (French Polynesia). We first constructed a DNA barcode library (plastid rbcL and trnH–psbA) for the two island floras including 145 fern species. We then used these DNA barcodes to identify more than 1300 field-collected gametophytes from 25 plots spanning an elevational gradient from 200 to 2000 m. We found that species richness of fern sporophytes conforms to the well-known unimodal (i.e., mid-elevation peak) pattern, reaching a maximum at ca. 1000 – 1200 m. Moreover, we found that fern sporophyte communities become increasingly phylogenetically clustered at high elevations. In contrast, species richness of fern gametophytes was consistent across sites, and gametophytes showed no correlation of phylogenetic community structure with elevation. Turnover of sporophyte and gametophyte communities was closely linked with elevation at shallow phylogenetic levels, but not at deeper nodes in the tree. Finally, we found several species for which gametophytes had broader ranges than sporophytes, including a vittarioid fern with abundant gametophytes but extremely rare sporophytes. Our study highlights the importance of including diverse life history stages in surveys of community structure, and has implications for the possible impacts of climate change on the distribution of fern diversity.
Data from: Contrasting leaf trait responses of conifer and broadleaved seedlings to altered resource availability are linked to resource strategies
<p>(1) Understanding tree seedling responses to water, nutrient and light availability is crucial to precisely predict potential shifts in composition and structure of forest communities under future climatic conditions.</p> <p>(2) We exposed seedlings of widespread central European tree species with contrasting leaf habit, deciduous broadleaves (DB) and evergreen conifers (EC), to factorial combinations of manipulated precipitation (100% and 50% of ambient), shade (40% and 60% of full sunlight) and nutrient availability (low and high NPK), and measured specific leaf area, C/N ratio, soluble sugars, starch and non-structural carbohydrate concentration, and δ<sup>13</sup>C of the leaves.</p> <p>(3) We found contrasting effects of water and nutrient availability on foliar traits of the two species groups: EC exhibited higher tolerance to low resource availability but also less plasticity in foliar traits, which is congruent with a "slow" resource strategy. In contrast, foliage of DB reacted particularly to altered nutrient availability, corresponding to a "fast" resource strategy with high foliar plasticity and rapid adjustments to resource fluctuations, commonly adopted by species with high growth rates.</p> <p>(4) We conclude that DB will respond to environmental change with foliar acclimation, while EC will either tolerate, to some extent, or shift their distribution range in response to environmental change.</p>
Data from: Contrasting complexity of adjacent habitats influences the strength of cascading predatory effects
Although cascading effects of top predators can help structure communities, their influence may vary across habitats that differentially protect prey. Therefore, to understand how and to what degree habitat complexity can affect trophic interactions in adjacent habitats, we used a combination of a broad regional-scale survey, manipulative field trials, and an outdoor mesocosm experiment to quantify predator–prey interaction strengths across four trophic levels. Within estuaries of the southeastern USA, bonnethead sharks (Sphyrna tiburo) hunt blue crabs on mudflats and adjacent oyster reefs, two habitats with vastly different aboveground structure. Using 12-h tethering trials of blue crabs we quantified habitat-dependent loss rates of 37% on reefs and 78% on mudflats. We hypothesized that the sharks' predatory effects on blue crabs would cascade down to release a lower-level mud crab predator, which subsequently would increase juvenile oyster mortality, but that the cascade strength would be habitat-dependent. We experimentally manipulated predator combinations in split-plot mesocosms containing reef and mudflat habitats, and quantified oyster mortality. Bonnetheads exerted strong consumptive and non-consumptive effects on blue crabs, which ceased eating oysters in the sharks' presence. However, mud crabs, regardless of shark and blue crab presence, continued to consume oysters, especially within the structural refuge of the reef where they kept oyster mortality high. Thus, bonnetheads indirectly boosted oyster survival, but only on the mudflat where mud crabs were less active. Our work demonstrates how structural differences in adjacent habitats can moderate trophic cascades, particularly when mesopredators exhibit differential use of structure and different sensitivities to top predators.
Accounting for imperfect detection in data from museums and herbaria when modeling species distributions: Combining and contrasting data-level versus model-level bias correction
The digitization of museum collections as well as an explosion in citizen science initiatives has resulted in a wealth of data that can be useful for understanding the global distribution of biodiversity, provided that the well-documented biases inherent in unstructured opportunistic data are accounted for. While traditionally used to model imperfect detection using structured data from systematic surveys of wildlife, occupancy models provide a framework for modelling the imperfect collection process that results in digital specimen data. In this study, we explore methods for adapting occupancy models for use with biased opportunistic occurrence data from museum specimens and citizen science platforms using 7 species of Anacardiaceae in Florida as a case study. We explored two methods of incorporating information about collection effort to inform our uncertainty around species presence: (1) filtering the data to exclude collectors unlikely to collect the focal species and (2) incorporating collection covariates (collection type, time of collection, and history of previous detections) into a model of collection probability. We found that the best models incorporated both the background data filtration step as well as collector covariates. Month, method of collection and whether a collector had previously collected the focal species were important predictors of collection probability. Efforts to standardize meta-data associated with data collection will improve efforts for modeling the spatial distribution of a variety of species.
Ndaka [ndk] Contrastive Vowels
<p>This is a set of sound files exemplifying the nine Ndaka [ndk] contrastive vowels.</p>
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Annotated Behaviour and Observability Dataset (ABODe)
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