Home About us Contact
|
Home About us Contact | ||
|
|
||
Significant Genetic Structuring (significant + genetic_structuring)
Selected AbstractsMicrosatellite variation and population structure in a declining Australian Hylid Litoria aureaMOLECULAR ECOLOGY, Issue 7 2004Emma L. Burns Abstract The green and golden bell frog (Litoria aurea) was once a common Australian Hylid. Today, many populations are small and fragmented as a result of dramatic declines in distribution and abundance. We undertook a large-scale assessment of genetic structure and diversity in L. aurea using four species-specific microsatellite markers. Twenty-one locations were sampled from throughout the species range covering 1000 km of the east coast of Australia. Levels of allelic diversity and heterozygosity were high (uncorrected mean alleles/locus and HE were 4.8,8.8 and 0.43,0.8, respectively) compared to other amphibian species and significant differences among sampled sites were recorded. Despite recent population declines, no sites displayed a genetic signature indicative of a population bottleneck. Significant genetic structuring (overall FST 0.172) was detected throughout the species range, but was relatively low compared to previous amphibian studies employing microsatellites. In addition we found that some areas sampled within continuous habitat showed evidence of weak genetic structuring (data subset FST 0.034). We conclude that maintaining areas of continuous habitat is critical to the conservation of the species and argue that population recovery and/or persistence in all areas sampled is possible if appropriate protection and management are afforded. [source] Analysis of Forensic SNPs in the Canine mtDNA HV1 Mutational Hotspot Region,JOURNAL OF FORENSIC SCIENCES, Issue 6 2008Danielle T. Baute M.S. Abstract:, A 60 bp sequence variation hotspot in the canine mitochondrial DNA hypervariable region 1 was evaluated for its use in forensic investigations. Nineteen haplotypes containing 18 single nucleotide polymorphisms were observed among laboratory-generated and GenBank-derived domestic dog sequences representing five regional localities in the U.S. Samples from the different localities were highly variable with the levels of intra-population variability being similar among the populations studied. AMOVA further confirmed that there was no significant genetic structuring of the populations. Assays using these haplotypes were robust, canid specific and portend a rapid method for correctly excluding individual dogs as noncontributors of forensic evidence. Species-specificity of the primers was confirmed by means of in-tube polymerase chain reaction of human and cat DNA and in-silico assessment of the genomes of several animal species. Breed-specific fragments were not detected among the common haplotypes but there is evidence that this assay may be capable of differentiating domestic dog, wolf, and coyote sequences. [source] Invasion genetics of the Eurasian round goby in North America: tracing sources and spread patternsMOLECULAR ECOLOGY, Issue 1 2009JOSHUA E. BROWN Abstract The Eurasian round goby Neogobius melanostomus (Apollonia melanostoma) invaded the North American Great Lakes in 1990 through ballast water, spread rapidly, and now is widely distributed and moving through adjacent tributaries. We analyse its genetic diversity and divergence patterns among 25 North American (N = 744) and 22 Eurasian (N = 414) locations using mitochondrial DNA cytochrome b gene sequences and seven nuclear microsatellite loci in order to: (i) identify the invasion's founding source(s), (ii) test for founder effects, (iii) evaluate whether the invasive range is genetically heterogeneous, and (iv) determine whether fringe and central areas differ in genetic diversity. Tests include FST analogues, neighbour-joining trees, haplotype networks, Bayesian assignment, Monmonier barrier analysis, and three-dimensional factorial correspondence analysis. We recovered 13 cytochrome b haplotypes and 232 microsatellite alleles in North America and compared these to variation we previously described across Eurasia. Results show: (i) the southern Dnieper River population was the primary Eurasian donor source for the round goby's invasion of North America, likely supplemented by some alleles from the Dniester and Southern Bug rivers, (ii) the overall invasion has high genetic diversity and experienced no founder effect, (iii) there is significant genetic structuring across North America, and (iv) some expansion areas show reduced numbers of alleles, whereas others appear to reflect secondary colonization. Sampling sites in Lake Huron's Saginaw Bay and Lake Ontario significantly differ from all others, having unique alleles that apparently originated from separate introductions. Substantial genetic variation, multiple founding sources, large number of propagules, and population structure thus likely aided the goby's ecological success. [source] Genetic structure among closely spaced leks in a peripheral population of lesser prairie-chickensMOLECULAR ECOLOGY, Issue 2 2004Juan L. Bouzat Abstract We evaluated the genetic structure of birds from four closely spaced leks in a peripheral population of lesser prairie-chickens (Tympanuchus pallidicinctus). Analyses of molecular variance revealed significant genetic structuring among birds from different leks for six microsatellite loci (FST = 0.036; P = 0.002), but we found no genetic differentiation at the mtDNA control region. Significant deviations from Hardy,Weinberg revealed an excess of homozygote genotypes within each of the leks studied (FIS = 0.190,0.307), indicative of increased inbreeding. Estimates of relatedness using microsatellite data suggest that the genetic structuring among lesser prairie-chicken leks occurs in part because of a lek mating system in which males at some leks are related. Structuring may also be caused by stochastic effects associated with a historical decline in population size leading to small, semi-isolated leks and high site fidelity by reproductive males. Results from this study suggest that microspatial genetic structuring may occur in lek-mating bird species with low levels of dispersal. [source] Phylogeographical structure, postglacial recolonization and barriers to gene flow in the distinctive Valais chromosome race of the common shrew (Sorex araneus)MOLECULAR ECOLOGY, Issue 4 2002N. Lugon-Moulin Abstract Using one male-inherited and eight biparentally inherited microsatellite markers, we investigate the population genetic structure of the Valais chromosome race of the common shrew (Sorex araneus) in the Central Alps of Europe. Unexpectedly, the Y-chromosome microsatellite suggests nearly complete absence of male gene flow among populations from the St-Bernard and Simplon regions (Switzerland). Autosomal markers also show significant genetic structuring among these two geographical areas. Isolation by distance is significant and possible barriers to gene flow exist in the study area. Two different approaches are used to better understand the geographical patterns and the causes of this structuring. Using a principal component analysis for which testing procedure exists, and partial Mantel tests, we show that the St-Bernard pass does not represent a significant barrier to gene flow although it culminates at 2469 m, close to the highest altitudinal record for this species. Similar results are found for the Simplon pass, indicating that both passes represented potential postglacial recolonization routes into Switzerland from Italian refugia after the last Pleistocene glaciations. In contrast with the weak effect of these mountain passes, the Rhône valley lowlands significantly reduce gene flow in this species. Natural obstacles (the large Rhône river) and unsuitable habitats (dry slopes) are both present in the valley. Moreover, anthropogenic changes to landscape structures are likely to have strongly reduced available habitats for this shrew in the lowlands, thereby promoting genetic differentiation of populations found on opposite sides of the Rhône valley. [source] Evidence for bias in estimates of local genetic structure due to sampling schemeANIMAL CONSERVATION, Issue 3 2006E. K. Latch Abstract Traditional population genetic analyses typically seek to characterize the genetic substructure caused by the nonrandom distribution of individuals. However, the genetic structuring of adult populations often does not remain constant over time, and may vary relative to season or life-history stages. Estimates of genetic structure may be biased if samples are collected at a single point in time, and will reflect the social organization of the species at the time the samples were collected. The complex population structures exhibited by many migratory species, where temporal shifts in social organization correspond to a large-scale shift in geographic distribution, serve as examples of the importance that time of sampling can have on estimates of genetic structure. However, it is often fine-scale genetic structure that is crucial for defining practical units for conservation and management and it is at this scale that distributional shifts of organisms relative to the timing of sampling may have a profound yet unrecognized impact on our ability to interpret genetic data. In this study, we used the wild turkey to investigate the effects of sampling regime on estimates of genetic structure at local scales. Using mitochondrial sequence data, nuclear microsatellite data and allozyme data, we found significant genetic structuring among localized winter flocks of wild turkeys. Conversely, we found no evidence for genetic structure among sampling locations during the spring, when wild turkeys exist in mixed assemblages of genetically differentiated winter flocks. If the lack of detectable genetic structure among individuals is due to an admixture of social units as in the case of wild turkeys during the spring, then the FIS value rather than the FST value may be the more informative statistic in regard to the levels of genetic structure among population subunits. [source] | ||||||||||