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21 results for “patchy population”
Genetic structure in patchy populations of a candidate foundation plant: a case study of Leymus chinensis using genetic and clonal diversity
<p><strong>PREMISE</strong>: The distribution of genetic diversity on the landscape has critical ecological and evolutionary implications. This may be especially the case on a local scale for foundation plant species since they create and define ecological communities, contributing disproportionately to ecosystem function.</p> <p><strong>METHODS</strong>: We examined the distribution of genetic diversity and clones, which we defined first as unique multilocus genotypes (MLG), and then by grouping similar MLGs into multilocus lineages (MLL). We used 186 markers from inter-simple sequence repeats (ISSR) across 358 ramets from 13 patches of the foundation grass <em>Leymus chinensis</em>. We examined the relationship between genetic and clonal diversities, their variation with patch-size, and the effect of the number of markers used to evaluate genetic diversity and structure in this species.</p> <p><strong>RESULTS</strong>: Every ramet had a unique MLG. Almost all patches consisted of individuals belonging to a single MLL. We confirmed this with a clustering algorithm to group related genotypes. The predominance of a single lineage within each patch could be the result of the accumulation of somatic mutations, limited dispersal, some sexual reproduction with partners mainly restricted to the same patch, or a combination of all three.</p> <p><strong>CONCLUSIONS</strong>: We found strong genetic structure among patches of <em>L. chinensis</em>. Consistent with previous work on the species, the clustering of similar genotypes within patches suggests that clonal reproduction combined with somatic mutation, limited dispersal, and some degree of sexual reproduction among neighbors causes individuals within a patch to be more closely related than among patches.</p>
Genetic structure in patchy populations of a candidate foundation plant: a case study of Leymus chinensis using genetic and clonal diversity
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Data from: Patchy distribution and low effective population size raise concern for an at-risk top predator
Aim: Understanding carnivore distribution is important for management decisions that aim to restore naturally-regulated ecosystems and preserve biodiversity. Eastern Wolves, a species at risk in Canada, are centralized in Algonquin Provincial Park and their ability to disperse and establish themselves elsewhere is limited by human-caused mortality associated with hunting, trapping, and vehicle collisions. Here, we refine our understanding of Eastern Wolf distribution and provide the first estimates of their effective population size. Location: Southern Ontario and Gatineau Quebec. Methods: We used noninvasive samples, as well as blood samples archived from other research projects, collected between 2010 – 2014 to generate autosomal microsatellite genotypes at 12 loci for 98 Canis individuals. We utilized Bayesian and multivariate clustering analyses to identify Eastern Wolves in regions that were previously unsampled. Both linkage disequilibrium and temporal approaches were used to estimate effective population size of Eastern Wolves. Results: Assignment tests identified 34 individuals as Eastern Wolves, primarily in or near two provincial parks: Killarney and Queen Elizabeth II Wildlands. Eastern Coyotes were identified in Bon Echo Provincial Park, Frontenac Provincial Park, and Gatineau Park, whereas many of the samples were admixed among the different Canis types. Effective population size (Ne) estimates ranged from 24.3 – 122.1 with a harmonic mean of 45.6. Main Conclusions: The identification of Eastern Wolves in the regions of Killarney and Queen Elizabeth II Wildlands Provincial Parks extends the range of Eastern Wolves north of the French River and southward into previously unidentified regions. The effective population size is low and raises concerns for long-term persistence of this threatened carnivore; values are dangerously close to critical values recommended for short-term persistence. These results provide important information for upcoming Eastern Wolf recovery plans associated with federal and provincial endangered species legislation.
Data from: Seascape habitat patchiness and hydrodynamics explain genetic structuring of kelp populations
Macroalgae underpin most temperate inshore ecosystems, but increasing macroalgal loss, fragmentation and range contractions are eroding connectivity among populations. Understanding loss, and predicting the likelihood of recovery, is dependent on knowledge of population connectivity and how it is mediated by variability in local seascapes. Although many studies of marine connectivity have focussed on influences of geographic distance on genetic structure, the contribution of intervening habitat is rarely considered. We tested the extent to which geographic separation, intervening suitable habitat (reef versus sand and open water) and local hydrodynamics (inferred from particle dispersal models) explained structuring of genetic variation at microsatellite loci in the habitat forming macroalga Lessonia corrugata. Genetic structuring was best explained by the availability of suitable intervening habitat (rocky reef) rather than by geographic separation, although biologically realistic estimates of dispersal probability also became important at smaller spatial scales. Our results indicate that ecological separation can be more influential than geographic distance on population genetic structuring, and this should be considered during the assessment of connectivity and gene flow in marine species.
Data from: Optimizing the trade-off between spatial and genetic sampling efforts in patchy populations: towards a better assessment of functional connectivity using an individual-based sampling scheme
Genetic data are increasingly used in landscape ecology for the indirect assessment of functional connectivity, i.e. the permeability of landscape to movements of organisms. Among available tools, matrix correlation analyses (e.g. Mantel tests or mixed models) are commonly used to test for the relationship between pairwise genetic distances and movement costs incurred by dispersing individuals. When organisms are spatially clustered, a population-based sampling scheme (PSS) is usually performed, so that a large number of genotypes can be used to compute pairwise genetic distances on the basis of allelic frequencies. Because of financial constraints, this kind of sampling scheme implies a drastic reduction in the number of sampled aggregates, thereby reducing sampling coverage at the landscape level. We used matrix correlation analyses on simulated and empirical genetic datasets to investigate the efficiency of an individual-based sampling scheme (ISS) in detecting isolation-by-distance and isolation-by-barrier patterns. Provided that pseudo-replication issues are taken into account (e.g. through restricted permutations in Mantel tests), we showed that the use of inter-individual measures of genotypic dissimilarity may efficiently replace inter-population measures of genetic differentiation: the sampling of only three or four individuals per aggregate may be sufficient to efficiently detect specific genetic patterns in most situations. The ISS proved to be a promising methodological alternative to the more conventional PSS, offering much flexibility in the spatial design of sampling schemes and ensuring an optimal representativeness of landscape heterogeneity in data, with few aggregates left unsampled. Each strategy offering specific advantages, a combined use of both sampling schemes is discussed.
Data from: Does population distribution matter? Influence of a patchy versus continuous distribution on genetic patterns in a wind-pollinated shrub
Aim: Uniform spatial population distributions are predicted to result in lower among-population genetic differentiation and higher within-population genetic diversity than naturally patchy distributions, but there have been surprisingly few attempts to isolate this effect from confounding factors. We studied the widespread wind-pollinated shrub Allocasuarina humilis that is common in a geologically-stable landscape characterised by long-term population persistence to test the influence of semi-continuous versus patchy population distributions on genetic patterns. We also investigated whether A. humilis shows the high population connectedness and genetic diversity typically associated with wind pollination, a relatively uncommon and little-studied syndrome in this landscape. Location: Heath-shrublands ('heath') and forests of south-western Australia. Methods: Populations were sampled from heath and forest regions, which respectively exhibited semi-continuous and patchy population distributions. Genetic structure and diversity were assessed for 27 populations using eight nuclear microsatellite markers and three chloroplast regions. Phylogeographic history was examined using Bayesian phylogeny reconstruction, parsimony analysis and tests of expansion. Results: High haplotype diversity is consistent with long-term population persistence across most of the species' range. Nuclear markers showed low overall population differentiation and no geographical structure over ~900 km, reflecting extensive pollen dispersal. For both marker types, patchily-distributed forest populations were substantially more differentiated with significantly lower within-population diversity than semi-continuous heath populations. Phylogeographic analysis revealed evidence for earlier colonization of heath than forest and recent expansion into wetter forests, consistent with progressive long-term climatic drying. Main conclusions: High population connectedness and genetic diversity probably resulted from wind pollination in combination with dioecy and long life span. Patchy population distributions appear to have influenced genetic structure and diversity through lower pollen and seed dispersal, lower effective population sizes and greater genetic drift. Our approach illustrates the value of minimising confounding variables by testing the effect of a variable ecological trait within a single species.
Combining population genomics with demographic analyses highlights habitat patchiness and larval dispersal as determinants of connectivity in coastal fish species
<p>Gene flow shapes spatial genetic structure as well as the potential for local adaptation of populations. Among marine animals with non-migratory adults, the presence or absence of a pelagic larval stage is thought to be a key determinant in shaping gene flow and the genetic structure of populations. In addition, the spatial distribution of suitable habitats will influence the distribution of biological populations and their pattern of gene flow. We used whole genome sequencing to study demographic history and reduced representation (ddRAD) sequencing data to analyze spatial genetic structure in the broadnosed pipefish (<em>Syngnathus typhle</em>). Its main habitat are seagrass meadows, which along the study coast (SW Norway) have a patchy distribution. Combining the results from several analyses including scans for selection, suggests that stochastic genetic drift has shaped the observed population structure largely due to its patchy habitat distribution. The restricted gene flow is further driven by life history traits such as the presence of parental care combined with no pelagic life stages, resulting in a clear isolation-by-distance pattern spanning 100s of kilometers.</p> <p>The spatial scale of demographic connectivity was inferred from long-term (~30 year) census population counts that uncovered a sharp decline in spatial correlations in abundance with distance (37% decorrelation over 2 km). These findings were contrasted with data from two other fish species sampled along the same coastline, both having pelagic larval stages lasting ~20 days (corkwing wrasse, <em>Symphodus melops</em>, and black goby, <em>Gobus niger</em>) where the population structure is not that evident. For these species, we found a wider spatial scale of demographic connectivity (decorrelation distances of 14 and 28 km, respectively), and weaker isolation-by-distance except at one point along the coast where both species revealed a strong barrier to gene flow, seemingly due to a lack of suitable habitat. Combined, these findings suggest that habitat fragmentation and absence of a pelagic larval stage in pipefish strongly increases geographic structuring, while the pelagic larvae of wrasse and goby increase genetic and demographic connectivity, except over extensive habitat shifts.</p>
Data from: Combined analyses of kinship and FST suggest potential drivers of chaotic genetic patchiness in high gene flow populations
We combine kinship estimates with traditional F-statistics to explain contemporary drivers of population genetic differentiation despite high gene flow. We investigate range-wide population genetic structure of the California spiny (or red rock) lobster (Panulirus interruptus) and find slight, but significant global population differentiation in mtDNA (ΦST = 0.006, P = 0.001; Dest_Chao = 0.025) and seven nuclear microsatellites (FST = 0.004, P < 0.001; Dest_Chao = 0.03), despite the species' 240- to 330-day pelagic larval duration. Significant population structure does not correlate with distance between sampling locations, and pairwise FST between adjacent sites often exceeds that among geographically distant locations. This result would typically be interpreted as unexplainable, chaotic genetic patchiness. However, kinship levels differ significantly among sites (pseudo-F16,988 = 1.39, P = 0.001), and ten of 17 sample sites have significantly greater numbers of kin than expected by chance (P < 0.05). Moreover, a higher proportion of kin within sites strongly correlates with greater genetic differentiation among sites (Dest_Chao, R2 = 0.66, P < 0.005). Sites with elevated mean kinship were geographically proximate to regions of high upwelling intensity (R2 = 0.41, P = 0.0009). These results indicate that P. interruptus does not maintain a single homogenous population, despite extreme dispersal potential. Instead, these lobsters appear to either have substantial localized recruitment or maintain planktonic larval cohesiveness whereby siblings more likely settle together than disperse across sites. More broadly, our results contribute to a growing number of studies showing that low FST and high family structure across populations can coexist, illuminating the foundations of cryptic genetic patterns and the nature of marine dispersal.
Context-dependent dispersal determines relatedness and genetic structure in a patchy amphibian population
<p>Dispersal is a central process in ecology and evolution with far reaching consequences for the dynamics and genetics of spatially structured populations (SSPs). Individuals can adjust their decisions to disperse according to local fitness prospects, resulting in context-dependent dispersal. By determining dispersal rate, distance, and direction, these individual-level decisions further modulate the demography, relatedness, and genetic structure of SSPs. Here, we examined how context-dependent dispersal influences the dynamics and genetics of a Great Crested Newt (<i>Triturus cristatus</i>) SSP. We collected capture-recapture data of 5564 individuals and genetic data of 950 individuals across a SSP in northern Germany. We added genetic data from six sites outside this SSP to assess genetic structure and gene flow at a regional level. Dispersal rates within the SSP were high but dispersal distances were short. Dispersal was context-dependent: individuals preferentially immigrated into high-quality ponds where breeding probabilities were higher. The studied SSP behaved like a patchy population, where subpopulations at each pond were demographically interdependent. High context-dependent dispersal led to weak but significant spatial genetic structure and relatedness within the SSP. At the regional level, a strong hierarchical genetic structure with very few first-generation migrants as well as low effective dispersal rates suggest the presence of independent demographic units. Overall, our study highlights the importance of habitat quality for driving context-dependent dispersal and therefore demography and genetic structure in SSPs. Limited capacity for long-distance dispersal seems to increase genetic structure within a population and leads to demographic isolation in anthropogenic landscapes.</p>
Combining population genomics with demographic analyses highlights habitat patchiness and larval dispersal as determinants of connectivity in coastal fish species
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Data from: Patchy distribution and low effective population size raise concern for an at-risk top predator
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Data from: Local genetic patchiness but no regional differences between Indo-West Pacific populations of the dogtooth tuna Gymnosarda unicolor
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Data from: Optimizing the trade-off between spatial and genetic sampling efforts in patchy populations: towards a better assessment of functional connectivity using an individual-based sampling scheme
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Context-dependent dispersal determines relatedness and genetic structure in a patchy amphibian population
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Data from: Does population distribution matter? Influence of a patchy versus continuous distribution on genetic patterns in a wind-pollinated shrub
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Data from: Population genetic structure of a sandstone specialist and a generalist heath species at two levels of sandstone patchiness across the Strait of Gibraltar
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Data from: Combined analyses of kinship and FST suggest potential drivers of chaotic genetic patchiness in high gene flow populations
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Data from: Seascape habitat patchiness and hydrodynamics explain genetic structuring of kelp populations
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Data from: Infection in patchy populations: contrasting pathogen invasion success and dispersal at varying times since host colonisation
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Data from: Greater growth stability of trees in marginal habitats suggests a patchy pattern of population loss and retention in response to increased drought at the rear edge
Species rear range-edges are predicted to retract as climate warms, yet evidence of population persistence is accumulating. Accounting for this disparity is essential to enable prediction and planning for species' range retractions. At the Mediterranean edge of European beech-dominated temperate forest, we tested the hypothesis that individual performance should decline at the limit of the species' ecological tolerance in response to increased drought. We sampled 40 populations in a crossed factor design of geographical and ecological marginality and assessed tree growth resilience and decline in response to recent drought. Drought impacts occurred across the rear edge, but tree growth stability was unexpectedly high in geographically isolated marginal habitat and lower than anticipated in the species' continuous range and better-quality habitat. Our findings demonstrate that, at the rear edge, range shifts will be highly uneven and characterised by reduction in population density with local population retention rather than abrupt range retractions.
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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)
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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.