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3,655 results for “Structural data”
Data from: Defining conservation units with enhanced molecular tools to reveal fine scale structuring among Mediterranean green turtle rookeries
Understanding the connectivity among populations is a key research priority for species of conservation concern. Genetic tools are widely used for this purpose, but the results can be limited by the resolution of the genetic markers in relation to the species and geographic scale. Here, we investigate natal philopatry in green turtles (Chelonia mydas) from four rookeries within close geographic proximity (~ 200km) on the Mediterranean island of Cyprus. We genotyped hypervariable mtSTRs, a mtDNA control region sequence (CR) and 13 microsatellite loci to genetically characterise 479 green turtles using markers with different modes of inheritance. We demonstrated matrilineal stock structure for the first time among Mediterranean green turtle rookeries. This result contradicts previous regional assessments and supports a growing body of evidence that green turtles exhibit a more precise level of natal site fidelity than has commonly been recognised. The microsatellites detected weak male philopatry with significant stock structure among three of the six pairwise comparisons. The absence of Atlantic CR haplotypes and mtSTRs among these robust sample sizes reaffirm the reproductive isolation of Mediterranean green turtles and supports their status as a subpopulation. A power analysis effectively demonstrated that the mtDNA genetic markers previously employed to evaluate regional stock identity were confounded by an insufficient resolution considering the recent colonisation of this region. These findings improve the regional understanding of stock connectivity and illustrate the importance of using suitable genetic markers to define appropriate units for management and conservation.
Data from: Human disturbance increases functional but not structural variability of stream fungal communities
Temporal stability of ecosystem functions is often regulated by the same environmental factors that also shape diversity. Therefore, species diversity, ecosystem functions and their environmental regulators should be considered together to understand and predict the consequences of anthropogenic disturbances on ecosystems. We studied the influence of land-use disturbance (agriculture) and a natural stressor (low pH due to specific geology) on the temporal variability (variability among successive years) of fungal decomposer communities and leaf decomposition rates in streams. We used next-generation sequencing techniques (pyrosequencing) to determine the composition of fungal assemblages. Temporal variability of leaf decomposition was higher in human-disturbed streams than in circumneutral reference or naturally acidic sites, whereas the latter two did not differ. Fungal operational taxonomic unit (OTU) richness and evenness were lower in human-impacted sites than in circumneutral reference sites. However, there were no significant differences between stream types in the temporal variability of fungal community composition. Fungal OTU evenness was negatively and among-year variability of water chemistry positively related to temporal variability in leaf decomposition. Partial regressions showed that these two factors had independent effects on decomposition rates. Although the dominant OTUs in the disturbed streams were temporally stable, they did not maintain stable ecosystem functions, suggesting that variability in decomposition was driven mainly by changes in the metabolic responses of dominant taxa to environmental fluctuations. Our results show that leaf decomposition rates in reference sites vary little through time, supporting the use of leaf decomposition assays in bioassessment. Our results also highlight the importance of measuring not only the mean rates, but also temporal variability of process rates when assessing the influence of human disturbance on ecosystem functioning.
Data from: Seeing is believing? comparing plant-herbivore networks constructed by field co-occurrence and DNA barcoding methods for gaining insights into network structures
Plant-herbivore interaction networks provide information about community organization. Two methods are currently used to document pairwise interactions among plants and insect herbivores. One is the traditional method that collects plant-herbivore interaction data by field observation of insect occurrence on host plants. The other is the increasing application of newly developed molecular techniques based on DNA barcodes to the analysis of gut contents. The second method is more appealing because it documents realized interactions. To construct complete networks, each technique of network construction is urgent to be assessed. We addressed this question by comparing the effectiveness and reliability of the two methods in constructing plant-Lepidoptera larval network in a 50 ha subtropical forest in China. Our results showed that the accuracy of diet identification by observation method increased with the number of observed insect occurrences on food plants. In contrast, the molecular method using three plant DNA markers were able to identify food residues for 35.6% larvae and correctly resolved 77.3% plant (diet) species. Network analysis showed molecular networks had three-fold more unique host plant species but fewer links than the traditional networks had. The molecular method detected plants that were not sampled by the traditional method, e.g., bamboos, bryophytes and lianas in the diets of insect herbivores. The two networks also possessed significantly different structural properties. Our study indicates the traditional observation of co-occurrence is inadequate, while molecular method can provide higher species resolution of ecological interactions.
Data from: Aquatic community structure across an Andes-to-Amazon fluvial gradient
Aim: Little is known about factors affecting the elevational and longitudinal zonation of tropical Andean stream communities. We investigated epilithon, macroinvertebrate and fish assemblages along a 4100-m elevational–longitudinal gradient in an Andean headwater of the Amazon Basin. We interpret our results within the context of environmental factors, emphasizing temperature, as well as ecological theory relating shifts in metazoan functional feeding groups to shifts in basal resources along the fluvial continuum. Location: Arazá-Inambari-Madre de Dios watershed, south-eastern Peru. Methods: We sampled water physicochemistry, epilithon and macroinvertebrate diversity and abundance, and fish diversity at 18 main-stem and 14 tributary sites from high puna grasslands (4300 m a.s.l.) to Amazon Basin lowlands (200 m a.s.l.). Results: Water physicochemical parameters and the taxonomic and ecological structure of invertebrate and fish assemblages displayed mostly nonlinear responses to elevation: water temperature and percentage of macroinvertebrate taxa identified as leaf shredders had U-shaped responses; dissolved oxygen and percentage of macroinvertebrate taxa identified as grazers had hump-shaped responses. Epilithon richness increased slightly with elevation whereas macroinvertebrate and fish richness decreased. Main conclusions: Elevational gradients in physicochemical parameters are insufficient to explain abrupt and nonlinear shifts in community taxonomic and functional structure. Rather, trophic interactions, including predation and longitudinal turnover in basal food resources, seem to exert a stronger influence on the distributions of Andean aquatic organisms. A steep elevational decline in relative taxonomic diversity of leaf-shredding (versus algae-grazing) insects supports the hypothesis that temperature affects the functional composition of insect assemblages via its influence on microbial decomposition rates. This relationship, and the distributions of several insect and fish species across narrow elevational bands, suggests that Andean stream communities may be sensitive to global warming. Placer mining and road building impacts have already altered stream community structure, including the absence of many benthic species from low-elevation habitats.
Data from: Gynodioecy in structured populations: understanding fine-scale sex ratio variation in Beta vulgaris ssp. maritima
Natural selection, random processes, and gene flow are known to generate sex ratio variations among sexually polymorphic plant populations. In gynodioecious species, in which hermaphrodites and females coexist, the relative effect of these processes on the maintenance of sex polymorphism is still up for debate. The aim of this study was to document sex ratio and cytonuclear genetic variation at a very local scale in wind-pollinated gynodioecious Beta vulgaris ssp. maritima, and attempt to elucidate which processes explained the observed variation. The study sites were characterized by geographically distinct patches of individuals and appeared to be dynamic entities, with recurrent establishment of distinct haplotypes through independent founder events. Along with substantial variation in sex ratio and unexpectedly low gene flow within study sites, our results showed a high genetic differentiation among a mosaic of genetically distinct demes, with isolation by distance or abrupt genetic discontinuities taking place within a few tens of meters. Overall, random founder events with restricted gene flow could be primary determinants of sex structure, by promoting the clumping of sex-determining genes. Such high levels of sex structure provide a landscape for differential selection acting on sex-determining genes, which could modify the conditions of maintenance of gynodioecy in structured populations.
Data from: The structural and functional connectivity of the grassland plant Lychnis flos-cuculi
Understanding the relationship between structural and functional connectivity is essential for successful restoration and conservation management, particularly in intensely managed agricultural landscapes. We evaluated the relationship between structural and functional connectivity of the wetland plant Lychnis flos-cuculi in a fragmented agricultural landscape using landscape genetic and network approaches. First, we studied the effect of structural connectivity, such as geographic distance and various landscape elements (forest, agricultural land, settlements and ditch verges), on gene flow among populations as a measurement of functional connectivity. Second, we examined the effect of structural graph-theoretic connectivity measures on gene flow among populations and on genetic diversity within populations of L. flos-cuculi. Among landscape elements, forests hindered gene flow in L. flos-cuculi, whereas gene flow was independent of geographic distance. Among the structural graph-theoretic connectivity variables, only intrapopulation connectivity, which was based on population size, had a significant positive effect on gene flow, that is, more gene flow took place among larger populations. Unexpectedly, interpopulation connectivity of populations, which takes into account the spatial location and distance among populations, did not influence gene flow in L. flos-cuculi. However, higher observed heterozygosity and lower inbreeding was observed in populations characterised by higher structural interpopulation connectivity. This finding shows that a spatially coherent network of populations is significant for maintaining the genetic diversity of populations. Nevertheless, lack of significant relationships between gene flow and most of the structural connectivity measures suggests that structural connectivity does not necessarily correspond to functional connectivity.
Data from: Investigating population genetic structure in a highly mobile marine organism: the minke whale Balaenoptera acutorostrata acutorostrata in the North East Atlantic
Inferring the number of genetically distinct populations and their levels of connectivity is of key importance for the sustainable management and conservation of wildlife. This represents an extra challenge in the marine environment where there are few physical barriers to gene-flow, and populations may overlap in time and space. Several studies have investigated the population genetic structure within the North Atlantic minke whale with contrasting results. In order to address this issue, we analyzed ten microsatellite loci and 331 bp of the mitochondrial D-loop on 2990 whales sampled in the North East Atlantic in the period 2004 and 2007–2011. The primary findings were: (1) No spatial or temporal genetic differentiations were observed for either class of genetic marker. (2) mtDNA identified three distinct mitochondrial lineages without any underlying geographical pattern. (3) Nuclear markers showed evidence of a single panmictic population in the NE Atlantic according STRUCTURE's highest average likelihood found at K = 1. (4) When K = 2 was accepted, based on the Evanno's test, whales were divided into two more or less equally sized groups that showed significant genetic differentiation between them but without any sign of underlying geographic pattern. However, mtDNA for these individuals did not corroborate the differentiation. (5) In order to further evaluate the potential for cryptic structuring, a set of 100 in silico generated panmictic populations was examined using the same procedures as above showing genetic differentiation between two artificially divided groups, similar to the aforementioned observations. This demonstrates that clustering methods may spuriously reveal cryptic genetic structure. Based upon these data, we find no evidence to support the existence of spatial or cryptic population genetic structure of minke whales within the NE Atlantic. However, in order to conclusively evaluate population structure within this highly mobile species, more markers will be required.
Data from: Limited gene dispersal and spatial genetic structure as stabilizing factors in an ant-plant mutualism
Comparative studies of the population genetics of closely associated species are necessary to properly understand the evolution of these relationships because gene flow between populations affects the partners' evolutionary potential at the local scale. As a consequence (at least for antagonistic interactions), asymmetries in the strength of the genetic structures of the partner populations can result in one partner having a co-evolutionary advantage. Here, we assess the population genetic structure of partners engaged in a species-specific and obligatory mutualism: the Neotropical ant-plant, Hirtella physophora, and its ant associate, Allomerus decemarticulatus. Although the ant cannot complete its life cycle elsewhere than on H. physophora and the plant cannot live for long without the protection provided by A. decemarticulatus, these species also have antagonistic interactions: the ants have been shown to benefit from castrating their host plant and the plant is able to retaliate against too virulent ant colonies. We found similar short dispersal distances for both partners, resulting in the local transmission of the association and, thus, inbred populations in which too virulent castrating ants face the risk of local extinction due to the absence of H. physophora offspring. On the other hand, we show that the plant populations probably experienced greater gene flow than did the ant populations, thus enhancing the evolutionary potential of the plants. We conclude that such levels of spatial structure in the partners' populations can increase the stability of the mutualistic relationship. Indeed, the local transmission of the association enables partial alignments of the partners' interests, and population connectivity allows the plant retaliation mechanisms to be locally adapted to the castration behaviour of their symbionts.
Data from: Climate structuring of Batrachochytrium dendrobatidis infection in the threatened amphibians of the northern Western Ghats, India
Batrachochytrium dendrobatidis (Bd) is a pathogen killing amphibians worldwide. Its impact across much of Asia is poorly characterised. This study systematically surveyed amphibians for Bd across rocky plateaus in the northern section of the Western Ghats Biodiversity Hotspot, India, including for the first surveys of the plateaus in the coastal region. These ecosystems offer an epidemiological model system since they are characterised by differing levels of connectivity, edaphic and climatic conditions, and anthropogenic stressors. One hundred and eighteen individuals of 21 species of Anura and Apoda on 13 plateaus ranging from 67-1179m above sea level and 15.89 to 17.92° North Latitude were sampled. Using qPCR protocols 79% of species and 27% of individuals tested were positive for Bd. This is the first record of Bd in caecilians in India, the Critically Endangered Xanthophryne tigenrinus and Endangered Fejervarya cf. sahyadris. Mean site prevalence was 28.15%. Prevalence below the escarpment was 31.2% and 25.4% above. The intensity of infection (GE) showed the reverse pattern. Infection may be related to elevational temperature changes, thermal exclusion, inter-site connectivity and anthropogenic disturbance. Coastal plateaus may be thermal refuges from Bd. Infected amphibians represented a wide range of ecological traits posing interesting questions about transmission routes.
Data from: Genetic structure of Omani goats reveals admixture among populations from geographically proximal sites
The genetic diversity of most global goat populations has been assessed in recent decades using nuclear markers but remains unstudied in the south Arabian Peninsula, particularly in Sultanate of Oman, despite the importance of these animals for the local economy and food supply. Therefore, the present study provides a comparative analysis of the genetic diversity of five native Omani goat populations and evaluates possible admixture rates with the four most frequently imported goat populations from geographically proximal countries. Quality control of 15 loci was conducted and molecular characterization of nine populations was performed with 11 microsatellite markers. Accordingly, a data set based on 11 high informative microsatellites loci genotypes from nine populations was used to estimate the population genetic parameters. The summary statistics for the parameters depicted relatively highly diverse populations (Ho = 0.667, He = 0.663) with relatively low and mostly non-significant levels of inbreeding (FIS). Furthermore, the population substructure estimators (AMOVA) and population differentiation coefficient (FST) were indicated weak genetic differentiation among populations (P < 0.001).A finer analysis of the population substructure and differentiation using STRUCTURE, discriminant analyses of principal components (DAPCs) and a neighbor-joining (NJ) tree were supported a scenario that a high level of gene flow between populations from close geographical locations are the main evolutionary driving force. Thus, any future conservation strategy and breeding programs should include to preserve unique alleles that might be contributing to with stand the limited feed and requirement in desert ecosystems as well as economic traits.
Data from: The interplay of dispersal limitation, rivers, and historical events shapes the genetic structure of an Amazonian frog
Disentangling the impact of landscape features such as rivers and historical events on dispersal is a challenging but necessary task to gain a comprehensive picture of the evolution of diverse biota such as that found in Amazonia. Adenomera andreae, a small, territorial, terrestrial frog species of the Amazonian forest represents a good model for such studies. We combined Cytochrome b sequences with 12 microsatellites to investigate the genetic structure at two contrasted spatial scales in French Guiana: along a ~6 km transect to evaluate dispersal ability and between paired bank populations along a ~65 km stretch of the Approuague river to test the effect of rivers as barriers to dispersal. We observed significant spatial genetic structure between individuals at a remarkably small geographical scale and conclude that the species has a restricted dispersal ability likely tied to its life history traits. Mitochondrial and microsatellite data also indicate a high level of differentiation among populations on opposite banks of the river and, in some cases, among populations on the same riverbank. These results suggest that the observed population structure in A. andreae is due to restricted dispersal abilities combined with the action of rivers and Quaternary population isolation. Given that Amazonia hosts a great portion of anurans, as well as other small vertebrates, that display life history traits comparable to Adenomera andreae, we argue that our analyses provide new insights into the complex interactions among evolutionary processes shaping Amazonian biodiversity.
Data from: Noninvasive sampling reveals population genetic structure in the Royle's pika, Ochotona roylei, in the western Himalaya
Understanding population genetic structure of climate-sensitive herbivore species is important as it provides useful insights on how shifts in environmental conditions can alter their distribution and abundance. Herbivore responses to the environment can have a strong indirect cascading effect on community structure. This is particularly important for Royle's pika (Lagomorpha: Ochotona roylei), a herbivorous talus-dwelling species in alpine ecosystem, which forms a major prey base for many carnivores in the Himalayan arc. In this study, we used seven polymorphic microsatellite loci to detect evidence for recent changes in genetic diversity and population structure in Royle's pika across five locations sampled between 8 km to 160 km apart in the western Himalaya. Using four clustering approaches, we found the presence of significant contemporary genetic structure in Royle's pika populations. The detected genetic structure could be primarily attributed to the landscape features in alpine habitat (e.g. wide lowland valleys, rivers) that may act as semi-permeable barriers to gene flow and distribution of food plants, which are key determinants in spatial distribution of herbivores. Pika showed low inbreeding coefficients (FIS) and a high level of pairwise relatedness for individuals within 1km suggesting low dispersal abilities of talus-dwelling pikas. We have found evidence of a recent population bottleneck, possibly due to effects of environmental disturbances (e.g. snow melting patterns or thermal stress). Our results reveal significant evidence of isolation by distance in genetic differentiation (FST range = 0.04−0.19). This is the first population genetics study on Royle's pika, which helps to address evolutionary consequences of climate change which are expected to significantly affect the distribution and population dynamics in this talus dwelling species.
Data from: Genetic population structure of the blister beetle Gnathium minimum: core and peripheral populations
Populations on the periphery of a species' range tend to contain lower genetic variation and increased genetic differentiation compared to populations at the core of a species range, although some exceptions to this generalization occur. The blister beetle Gnathium minimum (Say) exhibits a wide-ranging distribution in the western United States but has peripheral or disjunct populations in Mexico, Florida, and Wisconsin. We used amplified fragment length polymorphism (AFLP) to compare the genetic variation and magnitude of genetic differentiation of the Wisconsin peripheral population to western core populations (Colorado, Kansas, New Mexico, and Texas). The proportion of polymorphic loci was 53.6 and 54.3, and expected heterozygosity 0.1864 and 0.1933 for the Kansas/Colorado (n = 87) and New Mexico/Texas (n = 35) regions, respectively. Specimens from Wisconsin (n = 121) had a lower proportion of polymorphic loci (38.4) and expected heterozygosity (0.1475). Genetic cluster estimation with GENELAND and F ST values showed greater genetic differentiation among the sampling locations within Wisconsin compared to core regions. Significant isolation-by-distance (IBD) was also observed in Wisconsin but not within the core regions. Lower genetic variation and increased isolation may reduce the Wisconsin population's ability to respond to change, thereby increasing their susceptibility to extinction.
Data from: Rodent-avoidance, topography and forest structure shape territory selection of a forest bird
Background - Understanding the factors underlying habitat selection is important in ecological and evolutionary contexts, and crucial for developing targeted conservation action in threatened species. However, the key factors associated to habitat selection often remain poorly known. We evaluated hypotheses related to abiotic and biotic factors thought to affect territory selection of the wood warbler Phylloscopus sibilatrix, a passerine living in an unpredictable environment owing to irregular rodent outbreaks and showing long-term declines particularly in Western Europe. Results - Comparing breeding territories to unoccupied areas located close-by revealed that territory occupancy in north-western Switzerland was positively related to slope steepness (topographic hypothesis supported) as well as to numbers of tussocks and trees, respectively, while it showed a unimodal relationship to cover of herb layer (forest structure hypothesis supported). Furthermore, a strong negative correlation between breeding territory occupancy and rodent numbers was found, suggesting that wood warblers avoid areas with high rodent densities (rodent-avoidance hypothesis supported). Comparing breeding territories to abandoned territories showed that breeding territories were located on steeper slopes (topography hypothesis supported), at larger distance from the forest edge (anthropogenic disturbance hypothesis supported) and harboured more trees (forest structure hypothesis supported) than abandoned territories. Conclusions - Aside from structural and topographic features of the habitat, wood warblers are affected by rodent numbers when settling, making habitat selection unpredictable from year to year. Forestry practices promoting relatively high tree densities, few bushes and an intermediate low-growing ground vegetation cover would enhance habitat quality for this declining passerine. In contrast, forestry practices aiming at increasing light in forests (selective thinning, group-felling) or keeping forest stands permanently covered with shrubs, bushes and trees of various sizes (continuous cover forestry) do not benefit the wood warbler.
Data from: Fine-scale genetic structure in a wild bird population: the role of limited dispersal and environmentally-based selection as causal factors
Individuals are typically not randomly distributed in space; consequently ecological and evolutionary theory depends heavily on understanding the spatial structure of populations. The central challenge of landscape genetics is therefore to link spatial heterogeneity of environments to population genetic structure. Here, we employ multivariate spatial analyses to identify environmentally induced genetic structures in a single breeding population of 1174 great tits Parus major genotyped at 4701 single-nucleotide polymorphism (SNP) loci. Despite the small spatial scale of the study relative to natal dispersal we found multiple axes of genetic structure. We built distance-based Moran's eigenvector maps to identify axes of pure spatial variation, which we used for spatial correction of regressions between SNPs and various external traits known to be related to fitness components (avian malaria infection risk, local density of conspecifics, oak tree density and altitude). We found clear evidence of fine-scale genetic structure, with 21, 7 and 9 significant SNPs respectively associated with infection risk by two species of avian malaria (Plasmodium circumflexum and P. relictum) and local conspecific density. Such fine-scale genetic structure relative to dispersal capabilities suggests ecological and evolutionary mechanisms maintain within-population genetic diversity in this population with the potential to drive micro-evolutionary change.
Data from: Defining spatial and temporal patterns of phylogeographic structure in Madagascar's iguanid lizards (Genus Oplurus)
Understanding the remarkably high species diversity and levels of endemism found among Madagascar's flora and fauna has been the focus of many studies. One hypothesis that has received much attention proposes that Pleistocene climate fluctuations spurred diversification. However, while spatial patterns of distribution and phylogenetic relationships can provide support for biogeographic predictions, temporal estimates of divergence are required to determine the fit of these geospatial patterns to climatic or biogeographic mechanisms. We use multilocus DNA sequence data to test whether divergence times among Malagasy iguanid lizards of the subfamily Oplurinae are compatible with a hypotheses of Quaternary diversification. We estimate the oplurine species tree and associated divergence times under a relaxed clock model. In addition, we examine the phylogeographic structure and population divergence times within two sister-species of Oplurus primarily distributed in the northwest and southwest of Madagascar (O. cuvieri and O. cyclurus, respectively). We find that divergence events among oplurine lineages occurred in the Oligocene and Miocene and are thus far older and incompatible with the hypothesis that recent climate fluctuations are related to current species diversity. However, the timing of intraspecific divergences and spatial patterns of population genetic structure within O. cuvieri and O. cyclurus suggest a role for both intrinsic barriers and recent climate fluctuations at population-level divergences. Integrating information across spatial and temporal scales allows us to identify and better understand the mechanisms generating patterns diversity.
Data from: Subtle changes in elevation shift bat-assemblage structure in Central Amazonia
The distribution patterns of animal species at local scales have been explained by direct influences of vegetation structure, topography, food distribution and availability. However, these variables can also interact and operate indirectly on the distribution of species. Here, we examined the direct and indirect effects of food availability (fruits and insects), vegetation clutter and elevation in structuring phyllostomid-bat assemblages in a continuous terra firme forest in Central Amazonia. Bats were captured in 49 plots over 25-km² of continuous forest. We captured 1138 bats belonging to 52 species with 7056 nethours of effort. Terrain elevation was the strongest predictor of species and guild compositions, and of bat abundance. However, changes in elevation were associated with changes in vegetation clutter, and availability of fruits and insects consumed by bats, which are likely to have had direct effects on bat assemblages. Frugivorous-bat composition was more influenced by availability of food-providing plants, while gleaning-animalivore composition was more influenced by the structural complexity of the vegetation. Although probably not causal, terrain elevation may be a reliable predictor of bat-assemblage structure at local scales in other regions. In situations where it is not possible to collect local variables, terrain elevation can substitute other variables, such as vegetation structure, and availability of fruits and insects.
Data from: Population genetic structure of the tree-hole tick Ixodes arboricola (Acari: Ixodidae) at different spatial scales
The endophilic tick Ixodes arboricola infests cavity-nesting birds, and its dispersal strongly depends on the movements of its host. Population genetic structure of I. arboricola was studied with seven polymorphic microsatellite markers. We collected 268 ticks from 76 nest boxes in four woodlots near Antwerp, Belgium. These nest boxes are mainly used by the principal hosts of I. arboricola, the great tit Parus major and the blue tit Cyanistes caeruleus. As these birds typically return to the same cavity for roosting or breeding, ticks within nest boxes were expected to be highly related, and tick populations were expected to be spatially structured among woodlots and among nest boxes within woodlots. In line with the expectations, genetic population structure was found among woodlots and among nest boxes within woodlots. Surprisingly, there was considerable genetic variation among ticks within nest boxes. This could be explained by continuous gene flow from ticks from nearby tree holes, yet this remains to be tested. A pairwise relatedness analysis conducted for all pairs of ticks within nest boxes showed that relatedness among larvae was much higher than among later instars, which suggests that larvae are the most important instar for tick dispersal. Overall, tick populations at the studied spatial scale are not as differentiated as predicted, which may influence the scale at which host–parasite evolution occurs.
Data from: Influence of northern limit range on genetic diversity and structure in a widespread North American tree, sugar maple (Acer saccharum Marshall)
Due to climate change, the ranges of many North-American tree species are expected to shift northward. Sugar maple (Acer saccharum Marshall) reaches its northern continuous distributional limit in north-eastern North America at the transition between boreal mixed-wood and temperate deciduous forests. We hypothesized that marginal fragmented northern populations from the boreal mixed-wood would have a distinct pattern of genetic structure and diversity. We analyzed 18 microsatellite loci variation in 23 populations distributed along three latitudinal transects (west, central and east) that encompass the continuous-discontinuous species range. Each transect was divided into two zones, continuous (temperate deciduous) and discontinuous (boreal mixed-wood), based on sugar maple stand abundance. Respective positive and negative relationships were found between the distance of each population to the northern limit (D north), and allelic richness (AR) and population differentiation (FST). These relations were tested for each transect separately; the pattern (discontinuous/continuous) remained significant only for the western transect. structure analysis revealed the presence of four clusters. The most northern populations of each transect were assigned to a distinct group. Asymmetrical gene flow occurred from the southern into the four northernmost populations. Southern populations in Québec may have originated from two different postglacial migration routes. No evidence was found to validate the hypothesis that northern populations were remnants of a larger population that had migrated further north of the species range after the retreat of the ice sheet. The northernmost sugar maple populations possibly originated from long distance dispersal.
Data from: Structural complexity of hunting habitat and territoriality increase the reversed sexual size dimorphism in diurnal raptors
Despite numerous efforts and many hypotheses to explain the selective pressures that may have favoured reversed sexual dimorphism (RSD) in raptors ‐ i.e. that the female is larger than the male ‐ some drivers of RSD are still unknown. Here we analyse how much variation in RSD is explained by hunting habitat structure, territoriality or territory size. We do so using data on diurnal raptors from the New World and the Western Palearctic – i.e. Cathartidae, Pandionidae, Accipitridae and Falconidae, the largest bird group showing RSD ‐ taking into account the phylogenetic relationships among species. Our results identify the type of the main prey as a major factor explaining RSD in raptors. We also found RSD to increase with increasing structural complexity in the hunting habitat from open or semi‐open habitats to forest interior. RSD also increased with increasing degree of territoriality of the species (non‐territorial < facultative < territorial). Finally, for territorial species RSD increased with increasing size of nesting territory. A model comprising only three predictor variables (prey type, structural complexity of hunting habitat and territoriality) explained up to 50% of the variation in RSD of European and American diurnal raptor species, and up to 40% of the variation in RSD when only territorial species were considered. Our results highlight the relevance of spatial facets of the niche – e.g. hunting habitat, territoriality and territory size ‐ in exerting selective pressures on the body size of diurnal raptors. These selective pressures, joint with already known trophic factors – e.g. diet ‐ are decisive for the evolution of the RSD, a key trait in the functional ecology of raptors. Our findings open up new perspectives in the study of sexual size divergence in birds.
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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.