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308 results for “density dependence”
Density-dependent changes of mating system and family structure in Brandt's voles (Lasiopodomys brandtii)
<p>A mating system is an important life history for animals dealing with changing environments. Population density affects the plasticity of a mating system and subsequently the family structure of animals, but its impacts on mating systems and social structures are rarely investigated by using molecular markers in field conditions. In this study, using microsatellite genetic markers, we examined the changes in the social and genetic mating system and family structure of Brandt's voles in the grassland of Inner Mongolia, China, under low-, medium-, and high-density enclosures (each enclosure 0.48-ha with 4 replicates.) We found, that with the increase in population density of the founder voles introduced into the enclosure in early spring, both sexes increased their number of genetic mating partners, while males increased their social partners, resulting in a more promiscuous mating system. The number of genetic fathers and mothers per family, the number of social offspring per founder male or female, and the proportion of extra-group offspring increased with increased density, indicating that the response of the family structure to density change which is consistent with the change in mating system observed in our study. Both male and female voles had multiple mates, but males had a larger number of social and genetic mates, the number of social and genetic offspring, and the number of social and genetic families. Our study highlights the significance of density-dependent plasticity of a mating system and family structure in affecting the population change of small mammals.</p>
Can livestock grazing dampen density dependent fluctuations in wild herbivore populations?
<p>Conservation policy for the high mountains of Asia increasingly recognises the need to encompass large multi-use landscapes beyond the protected area network. Due to limited long-term research in this region, our understanding of even fundamental processes, such as factors regulating large mammal populations is poor.</p> <p>Understanding the factors that regulate animal populations, especially those generating cyclicity, is a long-standing problem in ecology. Long-term research across multiple taxa (mainly from Europe and North America) has focused on the relative roles of food and predation in generating cyclicity in population dynamics. It remains unclear how trophic interactions that are influenced by anthropogenic stressors can affect population dynamics in human-modified landscapes. </p> <p>We present a 10-year study to compare the effects of livestock grazing on density dependent dynamics in two populations of bharal, <em>Pseudois nayaur</em>, in the Himalaya. We combine this with a mechanistic understanding of whether density dependence in these two sites acts predominantly by affecting adult survival or recruitment. We compared and quantified density dependence in the bharal population by fitting Bayesian Gompertz state‐space (GSS) models.</p> <p>We found evidence for negative density dependence which indicates possible cyclic dynamics in the bharal population of the site (Tabo) with low livestock density. The population dynamics of this site were driven by recruited offspring – with a 2-year density dependent lag effect – rather than adult survival. In the site with high livestock density (Kibber), this density dependence was not detected. We postulate the potential role of excessive grazing by livestock in affecting offspring recruitment, thereby affecting the bharal population in Kibber.</p> <p><em>Synthesis and applications</em>: Our results suggest that conservation action to facilitate wild herbivore population recovery, such as the development of protected areas and village reserves, needs to account for density dependent regulation. Sites with trophy hunting require continuous monitoring to understand the effects of density dependence so that appropriate hunting quotas can be formulated.</p>
Insect root feeders incur negative density-dependent damage across plant species in an alpine meadow
<p>Although herbivores are well known to incur positive density-dependent damage and mortality, thereby likely shaping plant community assembly, the response of belowground root feeders to changes in plant density has seldom been addressed. Locally rare plant species (with lower plant biomass per area) are often smaller with shallower roots than common species (with higher plant biomass per area) in competition-intensive grasslands. Likewise, root feeders are often distributed in the upper soil layers. We hypothesized therefore that root feeders would incur a negative density (biomass) dependent damage across plant species. To test this hypothesis, we investigated the diversity and abundance of plant and root feeder species in an alpine meadow, and determined the diet of the root feeders using metabarcoding. Across all species, root feeder load decreased with increasing aboveground plant biomass, root biomass, and total plant biomass per area, indicating negative density dependence of damage across plant species. Aboveground plant biomass per area increased with increasing individual plant biomass and root depth per area across species, suggesting that rare plant species were smaller in size and had shallower root systems compared to common plant species. Both root biomass per area and root feeder biomass per area decreased with soil depth, but the root feeder biomass decreased disproportionally faster compared to root biomass with increasing root depth. Root feeder load decreased with increasing root depth, but was not correlated with the feeding preference of root feeder species. Moreover, the prediction derived from a random process incorporating vertical distributions of root biomass and root feeder biomass significantly accounted for interspecific variation in root feeder load. In conclusion, the data indicate that root feeders incur negative density-dependent damage across plant species. On this basis, we suggest that manipulative experiments should be conducted to determine the effect of the negative density-dependent damage on plant community structure, and that different types of plant-animal interactions should be concurrently examined to fully understand the effect of plant density on overall herbivore damage across plant species.</p>
Data, Figures and Codes for "Experimental analyses of pore-size dependent biomineralization in porous media under various flow rate and bacterial density scenarios"
<pre>This repository contains the data, codes and figures for the manuscript <br>"Experimental analyses of pore-size-dependent biomineralization in porous media under various flow rate and bacterial density scenarios". <br><br>Comments welcome. </pre>
Do natural enemies mediate conspecific negative distance- and density-dependence of trees? A meta-analysis of exclusion experiments
<p>Conspecific negative distance- and density-dependence is believed to be one of the most important mechanisms controlling forest community assembly and species diversity globally. Plant pathogens, and insect and mammalian herbivores, are the most common natural enemy types that have been implicated in this phenomenon, but their general effects at different plant life stages are still unclear. Here, we conduct a meta-analysis of studies that involved robust manipulative experiments, using fungicides, insecticides, or exclosures, to assess the contributions of different natural enemy types to distance- and density-dependent effects at seed and seedling stages. We found that conspecific negative distance- and density-dependence was more common at the seedling stage. Only 30% of studies showed significant conspecific negative distance- and density-dependence. Among those studies, applying fungicides significantly reduced the effect of conspecific negative distance -dependent mortality. Excluding large mammals reduced the effect of conspecifics, but with only marginal significance (p < 0.1). Our study confirms that plant pathogens have a significant impact on distance -dependent mortality and suggests that the impacts of herbivores on seedlings have been understudied. At the seed stage, large and small mammals, respectively, appear to weaken and enhance negative conspecific distance-dependent mortality. Future research should identify specific agents of mortality, investigate the interactions among different enemy types, and assess how global change may affect natural enemies and thus influence the strength of conspecific distance- and density-dependence.</p>
Is negative density-dependent reproduction regulated by density-induced stress in root voles? Two field experiments
<p>Density dependence in reproduction plays an important role in stabilising population dynamics via immediate negative feedback from population density to reproductive output. Although previous studies have shown that negative density-dependent reproduction is associated with strong spacing behaviour and social interaction between individuals, the proximal mechanism for generating negative density-dependent reproduction remains unclear. In this study, we investigated the effects of density-induced stress on reproduction in root voles. Enclosed Founder populations were established by introducing six (low density) and 30 (high density) adults per sex into per enclosure (four enclosures per density in total) during the breeding season from April to July 2012 and from May to August 2015. Faecal corticosterone metabolite (FCM) levels, reproductive traits (recruitment rate and the proportion of reproductively active indivuduals), and founder population numbers were measured following repeated live-trapping in both years. The number of founders was negatively associated with recruitment rates and the proportion of reproductively active indivuduals, displaying a negative density-dependent reproduction. FCM level was positively associated with the number of founders. The number of founder females directly affected the proportion of reproductive females , and directly and indirectly through their FCM levels affected the recruitment rate; the effect of the number of male founders on the proportion of reproductive males was mediated by their FCM level. Our results showed that density-induced stress negatively affected reproductive traits and that density-induced stress is one ecological factor generating negative density-dependent reproduction.</p>
Demographic consequences of heterogeneity in conspecific density dependence among mast fruiting tropical trees
<p>The role of conspecific density dependence (CDD) in the maintenance of species richness is a central focus of tropical forest ecology. However, tests of CDD often ignore the integrated effects of CDD over multiple life-stages and their long-term impacts on population demography. We combined a 10-year time series of seed production, seedling recruitment and sapling and tree demography of three dominant Southeast Asian tree species that adopt a mast fruiting phenology. We used these data to construct individual-based models that examine the effects of CDD on population growth rates (λ) across life-history stages. Recruitment was driven by positive CDD for all species, supporting the predator satiation hypothesis, while negative CDD affected seedling and sapling growth of two species, significantly reducing λ. This negative CDD on juvenile growth overshadowed the positive CDD of recruitment, suggesting the cumulative effects of CDD during seedling and sapling development has greater importance than the positive CDD during infrequent masting events. Overall, CDD varied between positive and negative across life-history stages for all species, suggesting that assessments of CDD on transitions between just two stages (e.g. seeds-seedlings or juveniles-mature trees) likely misrepresents the importance of CDD on population growth and stability.</p>
Dataset of "Modelling the Frequency-Dependent Effective Excess Charge Density in Partially Saturated Porous Media"
<p>This dataset supports the research study 'Modelling the Frequency-Dependent Effective Excess Charge Density in Partially Saturated Porous Media' by S. G. Solazzi, L. D Thanh, K. Hu, and D. Jougnot.</p> <p>We provide with a commented MATLAB code (Freq_Sat_SP.m) for estimating the frequency-dependent (i) effective excess charge density, (ii) the electrokinetic coupling coefficient, and (iii) the effective dynamic permeability for partially saturated porous media. The code allows to consider fractal, lognormal, and double lognormal pore size distributions.</p>
Impacts of flowering density on pollen dispersal and gametic diversity are scale dependent
<p>Pollen dispersal is a key evolutionary and ecological process, but the degree to which variation in the density of concurrently flowering conspecific plants (i.e., co-flowering density) shapes pollination patterns remains understudied. We monitored co-flowering density and corresponding pollination patterns of the insect-pollinated palm <em>Oenocarpus bataua</em> in northwestern Ecuador and found that the influence of co-flowering density on these patterns was scale-dependent: high neighborhood densities were associated with reductions in pollen dispersal distance and gametic diversity of progeny arrays, whereas we observed the opposite pattern at the landscape scale. In addition, neighborhood co-flowering density also impacted forward pollen dispersal kernel parameters, suggesting that low neighborhood densities encourage pollen movement and may promote gene flow and genetic diversity. Our work reveals how co-flowering density at different spatial scales influences pollen movement, which in turn informs our broader understanding of the mechanisms underlying patterns of genetic diversity and gene flow within populations of plants.</p>
Turning summer into winter: nutrient dynamics, temperature, density dependence, and invasive species drive bioenergetic processes and growth of a keystone coldwater fish
<p>A combination of global changes such as species invasions, climate change, and nutrient pollution have altered ecosystems, food webs, and the bioenergetic processes that control growth. These changes are especially pronounced in freshwater ecosystems and often lead to rapid variation in fish growth and dependent ecosystems services such as fishery yield. Understanding the mechanisms driving growth responses to environmental change is important for interpreting past dynamics and sustainably managing ecosystems. This study uses integrated bioenergetics and growth modeling to understand how nutrient dynamics, species invasions, and changing temperatures have altered growth of the keystone pelagic whitefish (<em>Coregonus</em> <em>wartmanni</em>) in Lake Constance, Germany from 1925 to 2020. Growth variation was modeled by allowing covariates to alter temperature-dependent consumption, while size-specific metabolism varied only with temperature. Consumption and growth increased strongly to a maximum with phosphorous, and this effect was stronger when intraspecific competition (measured as whitefish biomass) was low. Increasing whitefish biomass reduced growth under mesotrophic conditions, but had no effect under oligotrophic conditions. In contrast, increasing competition with invasive three-spined stickleback (<em>Gasteosteus</em> <em>aculeauts</em>) was predicted to reduce growth even under oligotrophic conditions. The invasion has effectively turned summer into winter for whitefish, with older fish ceasing to grow and younger fish losing up to 10% of their body weight during the normal growing season in subsequent years. Warming is predicted to further reduce whitefish growth due to competition with invasive stickleback, which would further alter zooplankton food availability and reduce already low fishery yields. These results demonstrate the importance of considering biotic interactions and synergistic effects in global change studies, as well as the value of mechanistic-based models for understanding effects. Similar growth responses to ecosystem change are likely within and across ecosystems, and bioenergetic models can help understand effects to support informed ecosystem management.</p>
Data from: Positive spatial and temporal density-dependence drive early reproductive economy-of-scale effects of masting in a European old-growth forest community
<p>Masting, the spatial synchronization of interannual variation in seed production, can enhance reproductive efficiency through positive density-dependent processes (DD) that result in economies of scale (EOS), such as decreased pollen limitation and predator satiation in years of high reproduction. While the general occurrence of such EOS effects has been documented for masting species, few studies simultaneously investigated how spatial and temporal variation in reproduction affects pollination and predation. Furthermore, it is unclear whether the same mechanisms apply to co-occurring species with different levels of conspecific density, pollen limitation, and seed defenses. Here, we use a long-term data set with high spatial resolution of seed production of European beech (<em>Fagus sylvatica</em>), Norway spruce (<em>Picea abies</em>), and silver fir (<em>Abies alba</em>) in a primeval montane forest to investigate the relationship between reproductive effort, pollination efficiency, and predispersal predation by insects. We found that, along the temporal axis, the proportion of sound (fertilized and unpredated) seeds correlated positively with annual seed production over the 14-year study period in all three species, most strongly in beech and only weakly in silver fir. Moreover, the results show that in beech, spatial seed density interacts with plot-wide annual seed rain to enhance DD effects on seed predation, suggesting additive effects of synchronous reproduction on fitness benefits.</p> <p>Synthesis: For both pollination and predispersal predation in beech and spruce, the strongest DD effects occur at low levels of reproduction and quickly reach asymptotes at higher levels, suggesting the presence of thresholds in different EOS mechanisms. As variability and synchrony in mast-seeding are expected to decline with climate change, EOS effects driven by DD may remain stable until the threshold is reached, at which sudden declines would result in devastating effects on the availability of viable seeds for germination and recruitment.</p>
Data from: Density-dependent disease, life history tradeoffs, and the effect of leaf pathogens on a suite of co-occurring close relatives
1. Plant pathogens reduce the performance of their hosts and therefore may contribute to ecological mechanisms of coexistence. In Chesson's framework, pathogens contribute to stabilizing mechanisms when they intensify negative intraspecific interactions, such as density-dependent disease. Additionally, pathogens contribute to equalizing mechanisms when they reduce differences in performance among species. Life history tradeoffs predict higher susceptibility to pathogens in rapidly growing species, which could equalize performance among fast- and slow-growing species in the presence of pathogens. 2. In a coastal prairie in California, we studied the impact of leaf diseases on the performance of seventeen coexisting species of Trifolium and Medicago ("clovers"). We transplanted clovers in randomized arrays into the natural prairie community in three years of common garden experiments. We quantified infection rates by isolating fungi from leaves, and we measured disease severity as percent leaf area damaged. In a fungicide experiment, we measured the impact of infection on biomass and survival. We assessed whether disease on transplants was positively related to natural abundance of that species in the surrounding community, which we monitored over 5 years. We assessed life history tradeoffs by testing whether more rapidly growing species were more susceptible to pathogens. 3. Rank abundance of clover species was stable over five years despite marked environmental fluctuations. Across hosts, fungal infection was not linearly related to density, although transplants of species that were locally absent showed lower and more variable infection. Disease severity was greater for more abundant species in only one of three years, and response to fungicide was not stronger in more abundant species. Faster-growing species experienced greater fungal infection. Consistent with predictions of the leaf economic spectrum, the impact of infection on faster-growing species was less negative than for slower-growing species. 4. Our results suggest that life history tradeoffs in plant-pathogen interactions may contribute to equalizing mechanisms among species in this guild, but that the combined effects of greater infection with greater tolerance may limit rather than promote coexistence. We also found modest evidence that density-dependent disease may contribute to stabilizing mechanisms. Lack of host specificity, rapid evolution of host use, and temporal variation in climatic conditions may all influence the role that pathogens play in coexistence of these closely related plants.
Robust surface-to-mass coupling and turgor-dependent cell width determine bacterial dry-mass density
<p><span>During growth, cells must expand their cell volumes in coordination with biomass to control the level of cytoplasmic macromolecular crowding. Dry-mass density, the average ratio of dry mass to volume, is roughly constant between different nutrient conditions in bacteria, but it remains unknown whether cells maintain dry-mass density constant at the single-cell level and during non-steady conditions. Furthermore, the regulation of dry-mass density is fundamentally not understood in any organism. Using quantitative phase microscopy and a new image-analysis pipeline, we measured absolute single-cell mass and shape of the model organisms </span><i><span>Escherichia coli</span></i><span> and </span><i><span>Caulobacter crescentus</span></i><span> with improved precision and accuracy. We found that cells control dry-mass density indirectly, by expanding their surface, rather than volume, in direct proportion to biomass growth – according to a new surface growth law. At the same time, cell width is controlled independently. Therefore, cellular dry-mass density varies systematically with cell shape, both during the cell cycle or after nutrient shifts, while the surface-to-mass ratio remains nearly constant on the generation time scale. </span><span><span>Transient deviations from constancy during nutrient shifts can be reconciled with turgor-pressure variations and the resulting elastic changes in surface area.</span></span><span> Finally, we find that plastic changes of cell width after nutrient shifts are likely driven by turgor variations, demonstrating an important regulatory role of mechanical forces for width regulation. In conclusion, turgor-dependent cell width and a new, slowly varying surface-to-mass coupling constant are the independent variables that determine dry-mass density.</span></p>
Relatedness modulates density-dependent cannibalism rates in Drosophila
<p>1. Cannibalism is taxonomically widespread, and can have large impacts on individual fitness and population-level processes. As such, identifying how cannibalism rates vary in response to ecological cues is important for predicting species evolution and population dynamics.</p> <p>2. In this study, we aimed to identify several eco-evolutionary factors that affect cannibalism rate and measure how they interacted with one another.</p> <p>3. To do this, we conducted two experiments using complimentary methods to measure how cannibalism rates varied among larval Drosophila melanogaster and Drosophila simulans in response to changes in conspecific relatedness, social familiarity and density.</p> <p>4. We found that larvae were more likely to cannibalise non-related larval victims in both species, and that this effect increased at high densities in D. simulans. We found no evidence that Drosophila larvae use social familiarity to assess relatedness. Finally, in D. melanogaster, cannibalistic larvae prefer to cannibalise larvae that are being attacked by a greater number of conspecifics, implying that cues linked to conspecific abundance encourage cooperative cannibalism.</p> <p>5. By showing that cannibalism frequency in Drosophila spp. is sensitive to relatedness and several other factors, we reveal the complex relationship between cannibalism frequency and species ecology. Also, by showing that the effect of relatedness on cannibalism frequency is density-dependent, we advance the current understanding of how ecological variables interact to affect kin selection.</p> <p>ANALYSIS CODE IS WRITTEN IN R.</p>
Patterns of frequency and density dependence are highly variable in diverse annual flowering plant communities
<p>Applications of ecological theory to natural communities often assume that competitive, negative density-dependent processes are the only type of interaction important for diversity maintenance. Recent advances suggest that positive interactions within trophic levels (e.g. plant-plant) may also affect plant coexistence. Though positive plant-plant interactions theoretically might result in positive or nonmonotonic frequency or density dependence (FD/DD), less is known about how commonly these patterns occur, or which ecological processes might result in such patterns in natural plant communities. In this study, we test for signals of variable frequency and density dependence in annual flowering plant communities in Western Australia and search for evidence that interactions among plants during flowering might induce positive or nonmonotonic FD/DD in flowering plants. Using four common annual wildflower species, we ask if plant fecundity exhibits positive or nonmonotonic FD/DD and if pollinator-mediated plant-plant interactions during flowering change patterns of FD/DD relative to pollinator-independent plant interactions. Three species exhibited nonmonotonic (hump-shaped) density dependence, and only one species experienced strictly negative density dependence. Each species exhibited a different pattern of frequency dependence (positive, negative, weakly nonmonotonic, and no detectable frequency dependence). Pollinator-mediated plant-plant interactions during flowering induced both nonmonotonic density dependence and negative frequency dependence in one species. Importantly, the extent of variation in FD/DD observed in our study brings into question the dominance of negative density and frequency dependence in theory, suggesting instead that demographic responses of plants to their communities fall along a continuum of possible density- and frequency-dependent patterns.</p>
Population regulation and density‐dependent demography in the Trinidadian guppy
<p>Classic theory for density-dependent selection for delayed maturation requires that a population be regulated through some combination of adult fecundity and/or juvenile survival. We tested whether those demographic conditions were met in four experimental populations of Trinidadian guppies in which delayed maturation of males evolved when the densities of those populations became high. We used monthly mark-recapture data to examine population dynamics and demography in these populations. Three of the four populations displayed clear evidence of regulation. In all four populations, monthly adult survival rates were independent of biomass density or actually increased with increased biomass density. Juvenile recruitment, which is a combination of adult fecundity and juvenile survival, decreased as biomass density increased in all four populations. Demography showed marked seasonality, with greater survival and higher recruitment in the dry season than the wet season. Population regulation via juvenile recruitment supports the hypothesis that density-dependent selection was responsible for the evolution of delayed maturity in males. This body of work represents one of the few complete tests of density-dependent selection theory.</p>
Data for: Distance and density dependence in two native Bornean dipterocarp species
<p>The Janzen-Connell hypothesis proposes that density and distance-dependent mortality generated by specialist natural enemies prevent competitive dominance. Much literature on Janzen Connell mechanisms comes from the neotropics, and evidence of the role of distance and density-dependence is still relatively sparse. We tested the predictions of the J-C hypothesis in a South-East Asian system dominated by mast fruiting species. We hypothesized that seedling survival would decrease with distance and density, seedling growth would increase, and herbivory would decrease, according to the predictions of the Janzen-Connell hypothesis. Experiments were conducted to determine the strength of the Janzen Connell mechanism by manipulating the density and identity of tree species as a function of the distance from parent trees. Survival of conspecific seedlings was reduced near adult trees of one species, but not another. High densities of seedlings decreased the growth of conspecific seedlings of both species. In both species, herbivory rates decreased with distance in low-density areas. This study indicates that dipterocarp species experienced weak Janzen-Connell effects of distance and density dependence at the growth stage studied. Future studies in this system might focus on earlier life-history stages such as seeds and small seedlings, as well as studying mortality during mast-seeding events.</p>
Data from: Density-dependent reproductive success among sympatric dipterocarps during a major mast fruiting event
<p><span>The files hold the data for the paper entitled "</span>Density-dependent reproductive success among sympatric dipterocarps during a major mast fruiting event", which includes <span>(i) the weight and status of seeds collected with seed traps in a Bornean tropical forest during a mast fruiting event, and (ii) the results of a seed sowing experiment in primary and secondary forests. Study site was t</span>he Deramakot and Tangkulap Forest Reserves, Sabah, Malaysia (5°14– 30'N, 117°11–36'E)<span>.</span></p>
Density dependence of seed dispersal and fecundity profoundly alters the spread dynamics of plant populations
<ol> <li>Plant population spread has fundamental ecological and evolutionary importance. Both determinants of plant population spread, fecundity and dispersal, can be density-dependent, which should cause feedback between population densities and spread dynamics. Yet it is poorly understood how density-dependence affects key characteristics of spread: spread rate at which the location of the furthest forward individual moves, edge depth (the geographical area over which individuals contribute to spread) and population continuity (occupancy of the spreading population).</li> <li>We present a general modelling framework for analysing the effects of density-dependent fecundity and dispersal on population spread and parameterize this framework with experimental data from a common-garden experiment using five wind-dispersed plant species grown at different densities. </li> <li>Our model shows that density-dependent fecundity and dispersal strongly affect all three population spread characteristics for both exponential and lognormal dispersal kernels. Spread rate and edge depth are strongly correlated but show weaker correlations with population continuity. Positive density-dependence of fecundity increases all three spread characteristics. Increasingly positive density-dependence of dispersal increases spread rate and edge depth but generally decreases population continuity. Density-dependent fecundity and dispersal are largely additive in their effect on spread characteristics. For population continuity, the joint effects of density-dependent fecundity and dispersal are somewhat contingent on the dispersal kernel.</li> <li>The common-garden experiment and the experimentally parameterized mechanistic dispersal model revealed density-dependent fecundity and dispersal across study species. All study species exhibited negative density-dependent fecundity, but they differed qualitatively in the density-dependence of dispersal distance and probability of long-distance dispersal. The negative density-dependence of fecundity and dispersal found for three species reinforced each other in reducing spread rate and edge depth. The positively density-dependent dispersal found for two species markedly increased spread rate and edge depth. Population continuity was hardly affected by population density in all study species except Crepis sancta in which it was strongly reduced by negatively density-dependent fecundity.</li> <li> <em>Synthesis</em>. Density-dependent fecundity and seed dispersal profoundly alter population spread. In particular, positively density-dependent dispersal should promote the spread and genetic diversity of plant populations migrating under climate change but also complicate the control of invasive species.</li> </ol>
A Great Escape: resource availability and density-dependence shape population dynamics along trailing range edges
<p>Populations along geographical range limits are often exposed to unsuitable climate and low resource availability relative to core populations. As such, there has been a renewed focus on understanding the factors that determine range limits to better predict how species will respond to global change. Using recent theory on range limits and classical understanding of density dependence, we evaluated the influence of resource availability on the snowshoe hare Lepus americanus along its trailing range edge. We estimated variation in population density, habitat use, survival, and parasite loads to test the Great Escape Hypothesis (GEH), i.e. that density dependence determines, in part, a species' persistence along trailing edges. We found that variability in resource availability affected density and population fluctuations and led to trade-offs in survival for snowshoe hare populations in the northeastern USA. Hares living in resource-limited environments had lower and less variable population density, yet higher survival and lower parasitism compared to populations living in resource-rich environments. We suggest that density-dependent dynamics, elicited by resource availability, provide hares a unique survival advantage and partly explain persistence along their trailing edge. We hypothesize that this low-density escape from predation and parasitism occurs for other prey species along trailing edges, but the extent to which it occurs is likely conditional on the quality of matrix habitat. Our work indicates that biotic factors play an important role in shaping species' trailing edges and more detailed examination of non-climatic factors is warranted to better inform conservation and management decisions.</p>
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.