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464 results for “Population Genetic Diversity”
Genetic diversity, population structure, and linkage disequilibrium among tropical quality protein maize (QPM) lines assessed with high-density SNP markers
<p>The study of genetic diversity (GD), population structure, and linkage disequilibrium (LD) provides a better understanding of the genetic relationships between individuals in a population which can be utilized in crop research and improvement. Genotyping-by-sequencing (GBS) was used to detect and genotype single nucleotide polymorphisms (SNPs) in a collection of 74 quality protein maize (QPM) lines and further to characterize their genetic diversity, population structure, and linkage disequilibrium. A total of 235,214 high-quality SNPs were used for different genetic analyses except for structure analysis where 11,950 SNPs were used. Analysis of molecular variance (AMOVA) based on these SNPs revealed high genetic heterozygosity among the five populations with 1% of the total genetic variation present among the subpopulations and 99% of the variation among individuals within the populations. Population structure analysis using Bayesian-based clustering revealed that the 74 lines could be clustered into four groups. However, neighbor-joining trees indicate the lines are grouped into three major clusters. Further analysis using principal component analyses (PCA) clustered the genotypes into five groups which are concordant with the groups based on pedigree information. Higher genetic diversity was detected in population 1 with a GD value of 0.484 and the lowest in population 5 (0.396) and overall, with a mean of 0.434. The LD pattern in the quality protein maize was investigated and we observed a relatively rapid LD decay of 3.53kb and 10.66kb at r<sup>2</sup> =0.2 and r<sup>2</sup>= 0.1, respectively. Our findings provide important information for future Linkage mapping studies, genome-wide association analyses, and marker-assisted selective breeding of maize as well as genomic prediction-based selection in tropical germplasm.</p>
Geographical gradients of genetic diversity and differentiation among the southernmost marginal populations of Abies sachalinensis revealed by EST-SSR polymorphism
Research Highlights: We detected the longitudinal gradients of genetic diversity parameters, such as the number of alleles, effective number of alleles, heterozygosity, and inbreeding coefficient, and found that these might be attributable to climatic conditions, such as temperature and snow depth. Background and Objectives: Genetic diversity among local populations of a plant species at its distributional margin has long been of interest in ecological genetics. Populations at the distribution center grow well in favorable conditions, but those at the range margins are exposed to unfavorable environments, and the environmental conditions at establishment sites might reflect the genetic diversity of local populations. This is known as the central-marginal hypothesis in which marginal populations show lower genetic variation and higher differentiation than do central populations. In addition, genetic variation in a local population is influenced by phylogenetic constraints and the population history of selection under environmental constraints. In this study, we investigated this hypothesis in relation to Abies sachalinensis, a major conifer species in Hokkaido. Materials and methods: A total of 1,189 trees from 25 natural populations were analyzed using 19 EST-SSR loci. Results: The eastern populations; namely, those in the species distribution center, showed greater genetic diversity than did the western peripheral populations. Another important finding is that the southwestern marginal populations were highly differentiated from the other populations. Conclusions: These differences might be due to genetic drift in the small and isolated populations at the range margin. Therefore, our results indicated that the central-marginal hypothesis held true for the southernmost A. sachalinensis populations in Hokkaido.
Fig. 3 in Genetic diversity and population structure of Brycon nattereri (Characiformes: Bryconidae): a Neotropical fish under threat of extinction
Fig. 3. Haplotype network based on partial sequencing of the D-loop region (mtDNA) of 92 individuals of Brycon nattereri from the Laranjinha River. Circle sizes are pro- portional to haplotype frequency.
Data from: Drift happens: molecular genetic diversity and differentiation among populations of jewelweed (Impatiens capensis Meerb.) reflect fragmentation of floodplain forests
Landscape features often shape patterns of gene flow and genetic differentiation in plant species. Populations that are small and isolated enough also become subject to genetic drift. We examined patterns of gene flow and differentiation among 12 floodplain populations of the selfing annual jewelweed (Impatiens capensis Meerb.) nested within four river systems and two major watersheds in Wisconsin, USA. Floodplain forests and marshes provide a model system for assessing the effects of habitat fragmentation within agricultural/urban landscapes and for testing whether rivers act to genetically connect dispersed populations. We generated a panel of 12,856 single nucleotide polymorphisms and assessed genetic diversity, differentiation, gene flow, and drift. Clustering methods revealed strong population genetic structure with limited admixture and highly differentiated populations (mean multilocus FST = 0.32, FST' = 0.33). No signals of isolation by geographic distance or environment emerged, but alleles may flow along rivers given that genetic differentiation increased with river distance. Differentiation also increased in populations with fewer private alleles (R2 = 0.51) and higher local inbreeding (R2 = 0.22). Populations varied greatly in levels of local inbreeding (FIS = 0.2 to 0.9) and FIS declined in smaller, more isolated populations. These results suggest that genetic drift dominates other forces in structuring these Impatiens populations. In rapidly changing environments, species must migrate or genetically adapt. Habitat fragmentation limits both processes, potentially compromising the ability of species to persist in fragmented landscapes.
Georeferenced data for the study Environmental suitability throughout the late Quaternary explains population genetic diversity
<p>Data filtered from GBIF (datasetKey: 50c9509d-22c7-4a22-a47d-8c48425ef4a7) Contains 150 records of the <i>Sciurus aberti </i>squirrel filtered in latitudinal windows of 5 degrees from 20 to 45 degrees N. </p>
Data from: Chrysolaena obovata, A SPECIES NATIVE OF BRAZILIAN CERRADO: GENETIC DIVERSITY AND STRUCTURE OF NATURAL POPULATIONS AND POTENTIAL FOR INULIN PRODUCTION
<p><em>Chrysolaena obovata</em> (Less.) M. Dematteis, an herbaceous Asteraceae species widely distributed across different Brazilian Cerrado physiognomies, has underground organs, named rhizophores, that accumulate high concentrations of inulin-type fructans. These carbohydrates are recognized as beneficial soluble fibers for human health and are currently used in the food and pharmaceutical industries. Considering that fructans, in addition to their economic potential, provide plants with greater tolerance to drought, heat and cold, it is important to understand whether their metabolism is conserved in natural populations. In this work, we aimed to investigate if the levels of genetic diversity in the populations studied allow the selection of localities with a high genetic base and higher fructan content for future programs of <em>in</em> <em>situ</em> conservation and genetic improvement for inulin production. Therefore, we characterized the diversity, structure, and gene flow of seven natural populations from Brazilian Cerrado, using nine microsatellite loci (SSR). In addition, we compared whether the fructan composition varied between populations of different Cerrado phytophysiognomies. Overall, we found that <em>C. obovata</em> populations exhibited moderate levels of genetic diversity, low genetic differentiation, and high gene flow. This study identified two populations with less genetic diversity and therefore, greater attention should be given to conservation programs including these populations. Fructan metabolism is conserved in all populations, indicating that <em>C. obovata</em> is an important genetic resource with high potential for inulin production.</p> <p><strong>File descriptions</strong></p> <p>Population_code.txt - Contains a matrix that indicates the population_code, Population_name, Brazilian-state, Phytophysiognomy, Collection coordinates and Altitudes (m).</p> <p>Date_ Diaz et al.xlsx – Contains Genotypes crude of the individuals analyzed. Primer used for nine microsatellite loci (Camacho <em>et al</em> 2017). </p> <p>Carbohydrates_Diaz et al - Contains data for carbohydrates in <em>C. obovata</em> plant rhizophores in each population (BRA, UB, SD, SP).</p> <p><strong>Location: Brazilian Cerrado</strong></p>
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>
Effects of insularity on genetic diversity within and among natural populations
<p>We conducted a review of genetic diversity (GD) within and among populations in relation to categorical population size and isolation (together "insularity"). Using populations from within the same studies, we were able to control for between-study variation in methodology, as well as demographic and life histories. Contradictory to typical expectations, insularity had relatively minor effects on GD within and among population, which points to the more important roles of other factors in shaping evolutionary processes. Such effects of insularity were sometimes seen – particularly in systems (i.e. studies) where GD was already high overall. That is, insularity influenced GD in a study system when GD was high even in non-insular populations of the same system – suggesting an important role for the "scope" of influences on GD. These conclusions were more robust for within - population GD than among - population GD, although a number of biases might underlie this difference. Overall, our findings indicate that population-level genetic assumptions need to be tested rather than assumed in nature, particularly for topics highly relevant to current conservation management practices.</p> <p> </p>
Data from: Genome-wide association mapping within a local Arabidopsis thaliana population more fully reveals the genetic architecture for defensive metabolite diversity
<p>A paradoxical finding from genome-wide association studies (GWAS) in plants is that variation in metabolite profiles typically maps to a small number of loci, despite the complexity of underlying biosynthetic pathways. This discrepancy may partially arise from limitations presented by geographically diverse mapping panels. Properties of metabolic pathways that impede GWAS by diluting the additive effect of a causal variant, such as allelic and genic heterogeneity and epistasis, would be expected to increase in severity with the geographic range of the mapping panel. We hypothesized that a population from a single locality would reveal an expanded set of associated loci. We tested this in a French <em>Arabidopsis thaliana</em> population (< 1 km transect) by profiling and conducting GWAS for glucosinolates, a suite of defensive metabolites that have been studied in depth through functional and genetic mapping approaches. For two distinct classes of glucosinolates, we discovered more associations at biosynthetic loci than previous GWAS with continental-scale mapping panels. Candidate genes underlying novel associations were supported by concordance between their observed effects in the TOU-A population and previous functional genetic and biochemical characterization. Local populations complement geographically diverse mapping panels to reveal a more complete genetic architecture for metabolic traits.</p>
Fig. 2 in Genetic diversity of Egyptian populations of the African Common Toad (Sclerophrys regularis, Reuss 1833)
Fig. 2. Phylogenetic tree of African Common Toad, using COI haplotypes based on the Maximum Likelihood method. Numbers refer to localities mentioned in the text: 1. Sharm El-Shaikh; 2. Arish; 3. Ismailia; 4. Damietta; 5. Alexandria; 6. Matrouh; 7. Gharbiya; 8. Cairo; 9. SiwaOasis; 10. Bani Sweif; 11. Menia; 12. Sohag; 13. Qena; 14. Aswan.
Fig. 1 in Genetic Diversity In Peripheral And Central Populations Of Rusty-Necklaced Partridge (Alectoris Magna) Based On Mitochondrial And Microsatellite Dna
Fig. 1. Rusty-necklaced partridge sampling sites: 1 = Lanzhou, 2 = Jingyuan, 3 = Haiyuan, 4 = Dingxi, 5 = Huining, 6 = Wushan, 7 = Beidao, 8 = Lixian
Fig. 11 in Trypanosomes genetic diversity, polyparasitism and the population decline of the critically endangered Australian marsupial, the brush tailed bettong or woylie (Bettongia penicillata)
Fig. 11. Transmission electron micrograph of an epimastigote and an amastigote of G2 (Clade A). (A) Epimastigote in culture; Ax: Axoneme showing nine doublets of microtubules surrounding a central pair; Ac: Acidocalcisomes; Arrow: Subpellicular microtubules. (B) Amastigote inside a VERO cell. Scale bars = 0.5 µm (A), 1 µm (B).
Fig. 9 in Trypanosomes genetic diversity, polyparasitism and the population decline of the critically endangered Australian marsupial, the brush tailed bettong or woylie (Bettongia penicillata)
Fig. 9. Infection of Vero (A) and L6 cells (B) with G2 (Clade A) and T. cruzi as a positive control of infection (Diff-Quick stained). (A) Intracellular amastigotes of G2. (B) Intracellular amastigotes of T. cruzi. Scale bars = 10 µm.
Fig. 8 in Trypanosomes genetic diversity, polyparasitism and the population decline of the critically endangered Australian marsupial, the brush tailed bettong or woylie (Bettongia penicillata)
Fig. 8. Epimastigotes of G1 and G2 (Clade A) arranged in rosettes in culture. (A) Diff-Quick stained rosettes. (B) Rosettes in fresh wet preparations showing numerous intracellular acidocalcisomes. Scale bars = 10 µm.
Fig. 7 in Trypanosomes genetic diversity, polyparasitism and the population decline of the critically endangered Australian marsupial, the brush tailed bettong or woylie (Bettongia penicillata)
Fig. 7. Light microscopy of Diff-Quick stained blood and culture forms of G1 and G2 (Clade A) (A) Trypomastigote in blood of a woylie naturally infected; (B) slender epimastigote in culture; (C and D) shaped epimastigote in culture; (E) spheromastigote in culture; (F) spheromastigotes dividing in culture. Scale bars = 10 µm.
Fig. 6 in Trypanosomes genetic diversity, polyparasitism and the population decline of the critically endangered Australian marsupial, the brush tailed bettong or woylie (Bettongia penicillata)
Fig. 6. Structures suggestive of amastigotes (arrows) of G2 (Clade A) in heart tissue positive by PCR (H&E stained). Scale bars = (A) 20 µm, (B) 10 µm.
Fig. 5 in Trypanosomes genetic diversity, polyparasitism and the population decline of the critically endangered Australian marsupial, the brush tailed bettong or woylie (Bettongia penicillata)
Fig. 5. Histopathology of two woylies naturally infected with G2 (Clade A) (H&E stained). (A) Multifocal, moderate to severe, chronic, pyogranulomatous myocarditis and (B) endocarditis. (C) Mineralisation of heart tissue. (D) Tongue showing multifocal, moderate, chronic, pyogranulomatous glossitis. (E) Skeletal muscle degeneration. (F) Inflammatory cells around a blood vessel. Scale bars = 20 µm.
Fig. 3 in Trypanosomes genetic diversity, polyparasitism and the population decline of the critically endangered Australian marsupial, the brush tailed bettong or woylie (Bettongia penicillata)
Fig. 3. Phylogenetic relationships of the new trypanosome isolates from Western Australian marsupials based on gGAPDH sequences (~810 bp) using Mr Bayes. The tree was rooted with five sequences as outgroups. Bayesian posterior probabilities are shown at nodes. Bar, 0.07 substitutions per site.
Fig. 10 in Trypanosomes genetic diversity, polyparasitism and the population decline of the critically endangered Australian marsupial, the brush tailed bettong or woylie (Bettongia penicillata)
Fig. 10. Scanning electron micrograph of G2 (Clade A) grown in culture with Vero cells. (A) Trypomastigote invading a cell, with the flagella still external to the cell. (B) Dead cell(s) surrounded by amastigotes and trypomastigotes. Scale bars = 2 µm (A), 4 µm (B).
Fig. 4 in Trypanosomes genetic diversity, polyparasitism and the population decline of the critically endangered Australian marsupial, the brush tailed bettong or woylie (Bettongia penicillata)
Fig. 4. Prevalence of infection with trypanosomes within the different clades in woylies from the stable and declining populations. 95% confidence intervals (95% CI).
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