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1,598 results for “genetic diversity”
Data from: History matters more when explaining genetic diversity within the context of the core-periphery hypothesis
The core–periphery hypothesis (CPH) predicts that populations located at the periphery of a species' range should have lower levels of genetic variation than those at the centre of the range. However, most of the research on the CPH focuses on geographic distance and not on ecological distance, or uses categorical definitions of core and periphery to explain the distribution of genetic diversity. We use current climate data and historical climate data from the last glacial maxima to develop quantitative estimates of contemporary and historical ecological suitability using ecological niche models. We analysed genetic diversity using 12 polymorphic microsatellites to estimate changes in heterozygosity, allelic richness and population differentiation in 31 populations of the wood frog (Lithobates sylvaticus) spanning the species' entire eastern clade (33o to 45o latitude) from Alabama, USA, to Nova Scotia, Canada. Our data support predictions based on the CPH. Populations showed significant differences in genetic diversity across the range, with lower levels of genetic variation at the geographic range edge and in areas with lower levels of historical and contemporary ecological suitability. However, history and geography (not current ecological suitability) best explain the patterns. This study highlights the importance of examining more than just geography when assessing the CPH, and the importance of historical ecological suitability in the maintenance of genetic diversity and population differentiation.
Data from: Genetic diversity, linkage disequilibrium and selection signatures in Chinese and Western pigs revealed by genome-wide SNP markers
To investigate population structure, linkage disequilibrium (LD) pattern and selection signature at the genome level in Chinese and Western pigs, we genotyped 304 unrelated animals from 18 diverse populations using porcine 60 K SNP chips. We confirmed the divergent evolution between Chinese and Western pigs and showed distinct topological structures of the tested populations. We acquired the evidence for the introgression of Western pigs into two Chinese pig breeds. Analysis of runs of homozygosity revealed that historical inbreeding reduced genetic variability in several Chinese breeds. We found that intrapopulation LD extents are roughly comparable between Chinese and Western pigs. However, interpopulation LD is much longer in Western pigs compared with Chinese pigs with average r20.3 values of 125 kb for Western pigs and only 10.5 kb for Chinese pigs. The finding indicates that higher-density markers are required to capture LD with causal variants in genome-wide association studies and genomic selection on Chinese pigs. Further, we looked across the genome to identify candidate loci under selection using FST outlier tests on two contrast samples: Tibetan pigs versus lowland pigs and belted pigs against non-belted pigs. Interestingly, we highlighted several genes including ADAMTS12, SIM1 and NOS1 that show signatures of natural selection in Tibetan pigs and are likely important for genetic adaptation to high altitude. Comparison of our findings with previous reports indicates that the underlying genetic basis for high-altitude adaptation in Tibetan pigs, Tibetan peoples and yaks is likely distinct from one another. Moreover, we identified the strongest signal of directional selection at the EDNRB loci in Chinese belted pigs, supporting EDNRB as a promising candidate gene for the white belt coat color in Chinese pigs. Altogether, our findings advance the understanding of the genome biology of Chinese and Western pigs.
Data from: Molecular analysis of H7 avian influenza viruses from Australia and New Zealand: genetic diversity and relationships from 1976 to 2007
Full genome sequencing of 11 Australian and one New Zealand subtype H7 avian influenza A isolates has enabled the comparison of sequences from each of the genome segments to other sequenced subtype H7 avian influenza A. The inference of phylogenetic relationships for each segment has been used to develop a model of the natural history of these viruses in Australia. The Australian H7 hemagglutinins form a monophyletic clade, consistent with the long-term, independent evolution due to geographic isolation. Based on the analysis of the other available H7 hemagglutinins sequences, the three other geographic regions for which similar monophyletic clades have been observed were confirmed; these regions are Eurasia (Africa, Europe and Asia), North America and South America. Analysis of datasets of H7N1, H7N3, H7N7 neuraminidase sequences revealed congruent relationships indicating a similar pattern of geographically constrained independent evolution for each of the neuraminidase subtype datasets. This pattern of evolution in geographic isolation is supported by analysis of each of the six remaining segments of the Australian isolates. These data in combination with the occurrence of five different combinations of neuraminidase subtypes (H7N2, H7N3, H7N4, H7N6, H7N7) among the 11 Australian isolates suggests a single maintenance network of hosts, probably comprising several avian species, for subtype H7 avian influenza A in Australia. A clear time based evolution of the hemagglutinins sequences despite the occurrence of multiple neuraminidase types suggest a genetic pool from which a variety of reassorants arise rather than the presence of a small number of stable viral clones. This pattern of evolution is likely to occur in each of the regions mentioned above as well as possibly a new region comprising of New Zealand, based on the apparent genetic isolation of the isolate analyzed in this study.
Data from: Standing genetic diversity and selection at functional gene loci are associated with differential invasion success in two non-native fish species
Invasive species are expected to experience a unique combination of high genetic drift due to demographic factors while also experiencing strong selective pressures. The paradigm that reduced genetic diversity should limit the evolutionary potential of invasive species and thus their potential for range expansion has received little empirical support, possibly due to the choice of genetic markers. Our goal was to test for effects of genetic drift and selection at functional genetic markers as they relate to the invasion success of two paired invasive goby species, one widespread (successful) and one with limited range expansion (less successful). We genotyped fish using two marker types: single nucleotide polymorphisms (SNPs) in known-function, protein-coding genes and microsatellites to contrast the effects of neutral genetic processes. We identified reduced allelic variation in the invaded range for the less-successful tubenose goby. SNPs putatively under selection were responsible for the observed differences in population structure between marker types for round goby (successful) but not tubenose goby (less successful). A higher proportion of functional loci experienced divergent selection for round goby, suggesting increased evolutionary potential in invaded ranges may be associated with round goby's greater invasion success. Genes involved in thermal tolerance were divergent for round goby populations but not tubenose goby, consistent with the hypothesis that invasion success for fish in temperate regions is influenced by capacity for thermal tolerance. Our results highlight the need to incorporate functional genetic markers in studies to better assess evolutionary potential for the improved conservation and management of species.
Data from: Long live the alien: is high genetic diversity a pivotal aspect of crested porcupine (Hystrix cristata) long-lasting and successful invasion?
Studying the evolutionary dynamics of an alien species surviving and continuing to expand after several generations can provide fundamental information on the relevant features of clearly successful invasions. Here, we tackle this task by investigating the dynamics of the genetic diversity in invasive crested porcupine (Hystrix cristata) populations, introduced to Italy about 1500 years ago, which are still growing in size, distribution range and ecological niche. Using genome-wide RAD markers, we describe the structure of the genetic diversity and the demographic dynamics of the H. cristata invasive populations and compare their genetic diversity with that of native African populations of both H. cristata and its sister species, H. africaeaustralis. First, we demonstrate that genetic diversity is lower in both the invasive Italian and the North Africa source range relative to other native populations from sub-Saharan and South Africa. Second, we find evidence of multiple introduction events in the invasive range followed by very limited gene flow. Through coalescence-based demographic reconstructions, we also show that the bottleneck at introduction was mild and did not affect the introduced genetic diversity. Finally, we reveal that the current spatial expansion at the northern boundary of the range is following a leading-edge model characterized by a general reduction of genetic diversity towards the edge of the expanding range. We conclude that the level of genome-wide diversity of H. cristata invasive populations is less important in explaining its successful invasion than species-specific life-history traits or the phylogeographic history in the native source range.
Data from: Exploring the role of Micronesian islands in the maintenance of coral genetic diversity in the Pacific Ocean
Understanding how genetic diversity is maintained across patchy marine environments remains a fundamental problem in marine biology. The Coral Triangle, located in the Indo-West Pacific, is the center of marine biodiversity and has been proposed as an important source of genetic diversity for remote Pacific reefs. Several studies highlight Micronesia, a scattering of hundreds of small islands situated within the North Equatorial Counter Current, as a potentially important migration corridor. To test this hypothesis, we characterized the population genetic structure of two ecologically important congeneric species of reef-building corals across greater Micronesia, from Palau to the Marshall Islands. Genetic divergences between islands followed an isolation-by-distance pattern, with Acropora hyacinthus exhibiting greater genetic divergences than A. digitifera, suggesting different migration capabilities or different effective population sizes for these closely related species. We inferred dispersal distance using a biophysical larval transport model, which helped explain an additional 15-21% of genetic variation compared to between-island geographic distance alone. For both species, genetic divergence accumulates and genetic diversity diminishes with distance from the Coral Triangle, supporting the hypothesis that Micronesian islands act as important stepping-stones connecting the central Pacific with the species rich Coral Triangle. However, for A. hyacinthus, the species with lower genetic connectivity, immigration from the sub-equatorial Pacific begins to play a larger role in shaping diversity than input from the Coral Triangle. This work highlights the enormous dispersal potential of broadcast-spawning corals and identifies the biological and physical drivers that influence coral genetic diversity on a regional scale.
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: Environmental factors influence both abundance and genetic diversity in a widespread bird species
Genetic diversity is one of the key evolutionary variables that correlate with population size, being of critical importance for population viability and the persistence of species. Genetic diversity can also have important ecological consequences within populations, and in turn, ecological factors may drive patterns of genetic diversity. However, the relationship between the genetic diversity of a population and how this interacts with ecological processes has so far only been investigated in a few studies. Here, we investigate the link between ecological factors, local population size, and allelic diversity, using a field study of a common bird species, the house sparrow (Passer domesticus). We studied sparrows outside the breeding season in a confined small valley dominated by dispersed farms and small-scale agriculture in southern France. Population surveys at 36 locations revealed that sparrows were more abundant in locations with high food availability. We then captured and genotyped 891 house sparrows at 10 microsatellite loci from a subset of these locations (N = 12). Population genetic analyses revealed weak genetic structure, where each locality represented a distinct substructure within the study area. We found that food availability was the main factor among others tested to influence the genetic structure between locations. These results suggest that ecological factors can have strong impacts on both population size per se and intrapopulation genetic variation even at a small scale. On a more general level, our data indicate that a patchy environment and low dispersal rate can result in fine-scale patterns of genetic diversity. Given the importance of genetic diversity for population viability, combining ecological and genetic data can help to identify factors limiting population size and determine the conservation potential of populations.
Data from: Revisiting comparisons of genetic diversity in stable and declining species: assessing genome-wide polymorphism in North American bumble bees using RAD sequencing
Genetic variation is of key importance for a species' evolutionary potential, and its estimation is a major component of conservation studies. New DNA sequencing technologies have enabled the analysis of large portions of the genome in nonmodel species, promising highly accurate estimates of such population genetic parameters. Restriction site-associated DNA sequencing (RADseq) is used to analyse thousands of variants in the bumble bee species Bombus impatiens, which is common, and Bombus pensylvanicus, which is in decline. Previous microsatellite-based analyses have shown that gene diversity is lower in the declining B. pensylvanicus than in B. impatiens. RADseq nucleotide diversities appear much more similar in the two species. Both species exhibit allele frequencies consistent with historical population expansions. Differences in diversity observed at microsatellites thus do not appear to have arisen from long-term differences in population size and are either recent in origin or may result from mutational processes. Additional research is needed to explain these discrepancies and to investigate the best ways to integrate next-generation sequencing data and more traditional molecular markers in studies of genetic diversity.
Urbanization impacts apex predator gene flow but not genetic diversity across an urban-rural divide
<p>Apex predators are important indicators of intact natural ecosystems. They are also sensitive to urbanization because they require broad home ranges and extensive contiguous habitat to support their prey base. Pumas (<i>Puma concolor</i>) can persist near human developed areas, but urbanization may be detrimental to their movement ecology, population structure, and genetic diversity. To investigate potential effects of urbanization in population connectivity of pumas, we performed a landscape genomics study of 130 pumas on the rural Western Slope and more urbanized Front Range of Colorado, USA. Over 12,000 single nucleotide polymorphisms were genotyped using double-digest, restriction site-associated DNA sequencing (ddRADseq). We investigated patterns of gene flow and genetic diversity, and tested for correlations between key landscape variables and genetic distance to assess the effects of urbanization and other landscape factors on gene flow. Levels of genetic diversity were similar for the Western Slope and Front Range, but effective population sizes were smaller, genetic distances were higher, and there was more admixture in the more urbanized Front Range. Forest cover was strongly positively associated with puma gene flow on the Western Slope, while impervious surfaces restricted gene flow and more open, natural habitats enhanced gene flow on the Front Range. Landscape genomic analyses revealed differences in puma movement and gene flow patterns in rural versus urban settings. Our results highlight the utility of dense, genome-scale markers to document subtle impacts of urbanization on a wide-ranging carnivore living near a large urban center.</p>
Genomic time-series data show that gene flow maintains high genetic diversity despite substantial genetic drift in a butterfly species
<p>Effective population size affects the efficacy of selection, rate of evolution by drift, and neutral diversity levels. When species are subdivided into multiple populations connected by gene flow, evolutionary processes can depend on global or local effective population sizes. Theory predicts that high levels of diversity might be maintained by gene flow, even very low levels of gene flow, consistent with species long-term effective population size, but tests of this idea are mostly lacking. Here, we show that Lycaeides butterfly populations maintain low contemporary (variance) effective population sizes (e.g., ~200 individuals) and thus evolve rapidly by genetic drift. In contrast, populations harbored high levels of genetic diversity consistent with an effective population size several orders of magnitude larger. We hypothesized that the differences in the magnitude and variability of contemporary versus long-term effective population sizes were caused by gene flow of sufficient magnitude to maintain diversity but only subtly affect evolution on generational time scales. Consistent with this hypothesis, we detected low but non-trivial gene flow among populations. Furthermore, using short-term population-genomic time-series data, we documented patterns consistent with predictions from this hypothesis, including a weak but detectable excess of evolutionary change in the direction of the mean (migrant gene pool) allele frequencies across populations, and consistency in the direction of allele frequency change over time. The documented decoupling of diversity levels and short-term change by drift in Lycaeides has implications for our understanding of contemporary evolution and the maintenance of genetic variation in the wild.</p>
Figure 2 in Repeated sampling adds to the genetic diversity of Lepidochelys olivacea (Eschscholtz 1829) olive ridley sea turtle
Figure 2. Map of sea turtle migration for five tagged olive ridley sea turtles nesting on Campamento Tortuguero La Gloria, Jalisco, Mexico. Sea turtles with haplotype MLK are observed swimming into the pelagic zone in a south-southwest direction, and along the coast (solid line). The single sea turtle with the haplotype MLN also swam in a south-southwest direction (dotted line).
Figure 1. Haplotype network derived from 704 in Repeated sampling adds to the genetic diversity of Lepidochelys olivacea (Eschscholtz 1829) olive ridley sea turtle
Figure 1. Haplotype network derived from 704 bp mitochondrial D-loop fragment. Circle sizes are proportional to the frequency of each haplotype. The black circles are hypothetical haplotypes not sampled. Each colour represents the ocean basin where the sample was taken: blue is Pacific Ocean, yellow is Indian Ocean, red is Atlantic Ocean, and green is Indo-Pacific Ocean.
Figure 1 in Genetic diversity of Atherina hepsetus (Osteichthyes: Atherinidae) populations as determined by RFLP analysis of three mtDNA regions
Figure 1. Sampling sites: Monastiraki (MON), Panagopoula (PAN), Kiparissi (KIP), Tinos (TIN), Naxos (NAX), Samos (SAM), Nissiros (NIS), Leipsi (LEI), Kos (KOS), Lesvos (MYT) and Evvoia (EVV).
Figure 3 in Genetic diversity of Atherina hepsetus (Osteichthyes: Atherinidae) populations as determined by RFLP analysis of three mtDNA regions
Figure 3. Dollo parsimony (Farris 1977) dendrogram showing the relationships between the 15 mtDNA haplotypes detected. Numbers indicate the bootstrap support (10,000 replicates) of each node of the majority-rule consensus tree.
Oxytenanthera abyssinica (A. Rich.) Munro; lowland bamboo (Poaceae, Bambusinea) in Ethiopia: Genetic diversity, population structure and gene flow analysis
<p><span>As one of the most important non-timber forest resources, a potential alternative to wood and wood product and fastest-growing plant in the world (91 cm (35 in) per day), bamboo is a member of the grass family (Poaceae) and constitutes a single subfamily Bambusoideae. 67% of total area of bamboo in Africa and 7% of world total is contributed by Ethiopia giving more than 1.44 million hectares. Silica gel dried young fresh leaves from 130 individuals of O. abyssinica were collected for DNA extraction and PCR amplification. Each of the PCR amplified ISSR fragments using 19 ISSR primers were used to study band pattern and heterozigosity, level of polymorphism, calculating marker efficiency, Nei`s (H) and Shannon (I) genetic diversity, analysis of molecular variance (AMOVA), analysis for cluster, principal coordinates (PCoA) and admixture results. High genetic variation at species level was observed with the percentage of the polymorphic loci (PPL) = 84.48%. The H, I, observed number of alleles (Na) and effective number of alleles (Ne) at species level was 0.2702, 0.4061, 1.8448, and 1.4744, respectively, showing a relatively high level of genetic diversity. However, the genetic differentiation at the population level was relatively low. AMOVA using grouped populations revealed that, most of the diversity was distributed within the populations (61.05%) with F<sub>ST</sub> = 0.38949, F<sub>SC</sub> = 0.10486 and F<sub>CT</sub> = 0.31797. Cluster analysis grouped the populations into sharply distinct clusters, which could be attributed to cross pollination nature of the plant and long lived to the area. STRUCTURE analyses for all population and excluding Gambella population gives different result K = 2 and K = 11. Using these markers, we find strong evidence linking geographic origin of diversity and samples from Gambella Region found different from others and might tell the availability of additional bamboo species in the country.</span></p>
F in Genetic diversity in the Carabodes marginatus species group (Acarida, Oribatida, Carabodidae) as inferred from allozymes
F. 3. Two-dimensional plot of multilocus genotype profiles based on principal component analysis (PCA).
F in Genetic diversity in the Carabodes marginatus species group (Acarida, Oribatida, Carabodidae) as inferred from allozymes
F. 1. C. marginatus typicus (right) and morphotype with short marginal notogastral setae (left). Both specimens were collected on Mt. Amiata.
Figure 5. Maximum likelihood trees constructed from mitochondrial cytochrome c oxidase subunit I in Cryptic diversity in coastal Australasia: a morphological and mitonuclear genetic analysis of habitat-forming sibling species
Figure 5. Maximum likelihood trees constructed from mitochondrial cytochrome c oxidase subunit I (left; log likelihood: -399.5730) and nuclear adenine nucleotide transporter intron (right; log likelihood: -12170.8682) sequences of Pyura praeputialis and Pyura doppelgangera sp. nov. Nodal support from 1000 bootstrap replications (> 75%) is indicated next to some branches. Circles indicate regions in which a particular allele was present. For simplicity, allele frequencies are not indicated.
Figure 2 in Cryptic diversity in coastal Australasia: a morphological and mitonuclear genetic analysis of habitat-forming sibling species
Figure 2. Pyura doppelgangera sp. nov. A, anal border (view from above); B, anal border (lateral view); C, gonoduct left side; D, an individual specimen collected in Tasmania. Photograph: Carmen Primo; E, the same individual without tunic. Photograph: Carmen Primo; F, dorsal tubercle and lamina with languets; G, internal structure detailing the position of the hepatic gland, dorsal tubercle, gonad on the right side of the body and the gut and gonad on the left side. Scale bars: A-C = 1 mm; D, E = 20 mm; F = 2 mm; G = 10 mm.
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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.
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DANDI Archive for NWB datasets
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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.
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