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1.
Using our results and literature data on multilocus DNA fingerprinting, we propose a method of obtaining unbiased estimates of the between-population genetic similarity index and a measure of population subdivision based on modified Wright's F ST-statistics. On the basis of multiple comparison T 2 Hotelling's test and Holmes' procedure, the F ST-statistics was applied to assess differentiation of four (Pacific and Atlantic) subpopulations of humpback whale Megaptera novaeangliae, six populations of Californian island gray fox Urocyon littoralis, and geographically isolated Ob' and Yakutia populations of Siberian white crane Crus leucogeranus. It was shown that the regional humpback whale subpopulations do not constitute a single panmictic unit (P < 10–4). The subdivision index of the Pacific and Atlantic populations expressed in terms of F-statistics varied from 0.101 to 0.157. The differentiation estimates for the island fox populations, which ranged from 0.2109 to 0.4027, indicate that subdivision of these populations is a function of the distance between the islands, island size, and population size. In particular, the smallest and the greatest differences were found respectively between the populations of the geographically closest northern islands (F ST = 0.2157, F ST = 0.2109) and between those of the most distant northern and southern islands (F ST = 0.4027, F ST = 0.3869). Subdivision of the island populations with minimum areas and low population number was intermediate (F ST = 0.3789). Mean values of heterozygosity, within-population genetic similarity index, and the number of coinciding fragments for two random individuals of Siberian white crane from the Ob' and Yakutia population were not statistically significantly different (P 0.852, P 0.491, P 0.325). However, pairwise comparisons of mean F ST values indicated that the differentiation estimates for samples from these populations fall within the limits of population subdivision (P = 0.01). The subdivision estimate (0.108–0.133) of various groups of Siberian white cranes is comparable to interregional subdivision of humpback whale. Based on the results of this study, we recommend the approach based on modified Wright's F ST-statistics for studying genetic population structure aimed at detecting population subdivision.  相似文献   

2.
The genetic structure of five natural populations of common wild rice Oryza rufipogon Griff. from China, was investigated with 21 microsatellite loci and compared to estimates of genetic diversity and genetic differentiation detected by 22 allozyme loci. Microsatellite loci, as expected, have much higher levels of genetic diversity (mean values of A = 3.1, P = 73.3%, Ho = 0.358 and He = 0.345) than allozyme loci (mean values of A = 1.2, P = 12.7%, Ho = 0.020 and He = 0.030). Genetic differentiation detected by microsatellite loci ( FST = 0.468, mean I = 0.472) was higher than that for allozyme loci ( FST =0.388, mean I = 0.976). However, microsatellite markers showed less deviation from Hardy-Weinberg expectation (Wright's inbreeding coefficient FIS = -0.069) than do allozymes ( FIS = 0.337). These results suggest that microsatellite markers are powerful high-resolution tools for the accurate assessment of important parameters in population biology and conservation genetics of O. rufipogon, and offer advantages over allozyme markers.  相似文献   

3.
E S Dement'eva 《Genetika》1975,10(7):122-130
The article comprises the results on the analysis of the structure of the great Pamirs' population (of a higher rank) and of one of its parts, the subpopulation of the valley of the river Bartang. Wright's F coefficient was used for the statistical treatment of the data obtained in the course of the analysis. The FST estimates were obtained from the variances of the frequencies of the genes located in 5 loci (ABO, MN, P, Rh and P.T.C.) culculated for 23 samples of the great populations of the Pamirs and for 9 samples of the population of the Bartang river valley. The general inbreeding coefficient for the Pamirs FIT=0,0323, its random component FST=0,0017 and the non-random component FIS=0.0306.  相似文献   

4.
The estimation of population differentiation with microsatellite markers   总被引:54,自引:0,他引:54  
Microsatellite markers are routinely used to investigate the genetic structuring of natural populations. The knowledge of how genetic variation is partitioned among populations may have important implications not only in evolutionary biology and ecology, but also in conservation biology. Hence, reliable estimates of population differentiation are crucial to understand the connectivity among populations and represent important tools to develop conservation strategies. The estimation of differentiation is c from Wright's FST and/or Slatkin's RST, an FST -analogue assuming a stepwise mutation model. Both these statistics have their drawbacks. Furthermore, there is no clear consensus over their relative accuracy. In this review, we first discuss the consequences of different temporal and spatial sampling strategies on differentiation estimation. Then, we move to statistical problems directly associated with the estimation of population structuring itself, with particular emphasis on the effects of high mutation rates and mutation patterns of microsatellite loci. Finally, we discuss the biological interpretation of population structuring estimates.  相似文献   

5.
A technique for obtaining unbiased estimates of genetic parameters (allelic frequencies of RAPD loci, heterozygosity (H), Wright's F statistic, and Nei's genetic distances) in populations of the European (Capreolus capreolus L.) and Siberian (Capreolus pygargus Pall.) roe deer is presented. The technique employs jackknifing and multiple comparative analysis based on a modified Holmes's procedure for Bonferroni's test. It was demonstrated that samples from local groups of roe deer in the Trans-Ural region did not differ significantly in allelic frequencies (0.8, 0.81, and 0.78; P > 0.447) or Nei's genetic distances (0.0056, 0.0273, and 0.0218; P = 0.26), but they could be differentiated based on Wright's F statistic (0.0346, 0.0519, and 0.0450; P = 10(-9)). The parameters of intrapopulation heterozygosity (from 0.18 to 0.042) formed a gradient from the east to the west. Calibration estimates of molecular evolution rate in the family Cervidae obtained based on published data and Jukes-Cantor genetic distances estimated in this study demonstrated that the Siberian roe deer has split into two subspecies, C. pygargus pygargus Pall. and C. pygargus tianschanicus Satunin in the interval between 229 and 462.3 thousand years ago. The species formation of the Siberian and European roe deer was dated between 1.375 and 2.75 Myr ago. Based on the results obtained we recommend the approaches used in the study for analysis of population genetic structure and phylogenetic relationships between populations, subspecies, species, and higher taxa.  相似文献   

6.
An important characteristic of the genetic structure of populations, random inbreeding (interpopulation variation), was evaluated on the basis of quasi-genetic markers (surnames). The following methodological issues are considered: estimation of random inbreeding using the coefficient of isonymy fr in a subdivided population; a comparison of inbreeding levels calculated on the basis of surname frequencies using fr and Wright's FST; a comparison of inbreeding estimates obtained on the basis of surnames and genetic markers; inbreeding variation in populations of the same hierarchical rank; and planning of genetic studies of a subdivided population. The population of Adygs (an indigenous ethnic group of Northern Caucasus) was examined as a model subdivided population. The population system of Adygs is hierarchical. Parameters of random inbreeding were examined at each level of the system "ethnic group==>tribe==>geographic group of auls==>aul." Frequencies of surnames were collected subtotally. Data on frequencies of 1340 surnames in 61 auls representing all Adyg tribes were analyzed. In total, 60,000 people were examined. The inbreeding estimates obtained on the basis of Wright's FST and the coefficient of isonymy fr virtually coincided: for Adygs in general, FST x 10(2) = 2.13 and fr x 10(2) = 2.09. At the same time, the inbreeding level exhibited marked differences among tribes: in Shapsugs, these differences were an order of magnitude higher than in Kabardins (fr x 10(2) = 2.53 and 0.25, respectively). The inbreeding estimates for auls differed by two orders of magnitudes: fr x 10(2) = 0.07 and fr x 10(2) = 7.88. An analysis of ten auls yielded fully coinciding inbreeding estimates based on quasi-genetic (fr x 10(2) = 0.60) and classical (FST x 10(2) = 0.69) gene markers. Computer maps of surname distributions in Adygs (1340 maps) were constructed for the first time ever. Based on these maps, the map of random inbreeding in the Adyg population was obtained.  相似文献   

7.
A clear understanding of population structure is essential for assessing conservation status and implementing management strategies. A small, non-migratory population of humpback whales in the Arabian Sea is classified as “Endangered” on the IUCN Red List of Threatened Species, an assessment constrained by a lack of data, including limited understanding of its relationship to other populations. We analysed 11 microsatellite markers and mitochondrial DNA sequences extracted from 67 Arabian Sea humpback whale tissue samples and compared them to equivalent datasets from the Southern Hemisphere and North Pacific. Results show that the Arabian Sea population is highly distinct; estimates of gene flow and divergence times suggest a Southern Indian Ocean origin but indicate that it has been isolated for approximately 70,000 years, remarkable for a species that is typically highly migratory. Genetic diversity values are significantly lower than those obtained for Southern Hemisphere populations and signatures of ancient and recent genetic bottlenecks were identified. Our findings suggest this is the world''s most isolated humpback whale population, which, when combined with low population abundance estimates and anthropogenic threats, raises concern for its survival. We recommend an amendment of the status of the population to “Critically Endangered” on the IUCN Red List.  相似文献   

8.
Methods of estimating within- and between-population gene diversity in parthenogenetic species using mini- and microsatellite DNA markers and modified Wright's FST statistic are presented with special reference to model populations of lizards of the genus Darevskia (D. dahli, D. armeniaca, D. unisexualis). We used DNA fingerprinting data for several populations of these species examined earlier. The effects of variation in M13, minisatellite, (GACA)n and (TCC)n microsatellite loci on the formation of within-population gene diversity in parthenogenetic species D. dahli and D. armeniaca were shown to be different. The equality of the realized gene diversity H and its maximum possible value Hmax in two populations of D. dahli (Hmax = 0.032, H = 0.031, P < < 0.0431; Hmax = 0.024, H = 0.027, P = 0.09) and D. armeniaca (Hmax = 0.05, H = 0.053, P = 0.03; Hmax = 0.054, H = 0.055, P = 0.02) suggests that variation in (GACA)n loci substantially contributes to the maintenance of within-population genetic diversity. Analysis of between-population genetic diversity using loci M13, (GACA)n, and (TCC)n showed differentiation of D. dahli populations from northeastern and northwestern Armenia (FST = 0.0272, P = 3 x 10(-13)) and genetic homogeneity of the Armenian and Introduced to the Ukraine populations of D. armeniaca characteristic of one clone (FST = 0, P = 1).  相似文献   

9.
简曙光  吴梅  刘念   《广西植物》2005,25(6):566-569,561
采用等位酶技术,分析了葫芦苏铁5个居群的遗传多样性。分析6个酶系统,共获得了13个基因位点, 结果表明:葫芦苏铁具有较高水平的遗传变异性,多态位点百分率(P)为56.9%,等位基因平均数A=1.62,等 位基因多样性指数Ho=0.105,He=0.164,居群杂合体过量的位点为50%。居群遗传结构分析表明,大部分 遗传变异(93.6%)存在于居群内(FST=0.064),居群间分化程度甚微。根据葫芦苏铁的居群遗传结构式样并 结合相关研究,提出了就地保护所有居群,迁地保护从东一、王下和水田三个大居群取样的保护策略。  相似文献   

10.
Genetic diversity and differentiation of Kermode bear populations   总被引:5,自引:0,他引:5  
The Kermode bear is a white phase of the North American black bear that occurs in low to moderate frequency on British Columbia's mid-coast. To investigate the genetic uniqueness of populations containing the white phase, and to ascertain levels of gene flow among populations, we surveyed 10 highly polymorphic microsatellite loci, assayed from trapped bear hairs. A total of 216 unique bear genotypes, 18 of which were white, was sampled among 12 localities. Island populations, where Kermodes are most frequent, show approximately 4% less diversity than mainland populations, and the island richest in white bears (Gribbell) exhibited substantial genetic isolation, with a mean pairwise FST of 0.14 with other localities. Among all localities, FST for the molecular variant underlying the coat-colour difference (A893G) was 0.223, which falls into the 95th percentile of the distribution of FST values among microsatellite alleles, suggestive of greater differentiation for coat colour than expected under neutrality. Control-region sequences confirm that Kermode bears are part of a coastal or western lineage of black bears whose existence predates the Wisconsin glaciation, but microsatellite variation gave no evidence of past population expansion. We conclude that Kermodism was established and is maintained in populations by a combination of genetic isolation and somewhat reduced population sizes in insular habitat, with the possible contribution of selective pressure and/or nonrandom mating.  相似文献   

11.
The relative roles of natural selection and direct environmental induction, as well as of natural selection and genetic drift, in creating clinal latitudinal variation in quantitative traits have seldom been assessed in vertebrates. To address these issues, we compared molecular and quantitative genetic differentiation between six common frog (Rana temporaria) populations along an approximately 1600 km long latitudinal gradient across Scandinavia. The degree of population differentiation (QST approximately 0.81) in three heritable quantitative traits (age and size at metamorphosis, growth rate) exceeded that in eight (neutral) microsatellite loci (FST = 0.24). Isolation by distance was clear for both neutral markers and quantitative traits, but considerably stronger for one of the three quantitative traits than for neutral markers. QST estimates obtained using animals subjected to different rearing conditions (temperature and food treatments) revealed some environmental dependency in patterns of population divergence in quantitative traits, but in general, these effects were weak in comparison to overall patterns. Pairwise comparisons of FST and QST estimates across populations and treatments revealed that the degree of quantitative trait differentiation was not generally predictable from knowledge of that in molecular markers. In fact, both positive and negative correlations were observed depending on conditions where the quantitative genetic variability had been measured. All in all, the results suggest a very high degree of genetic subdivision both in neutral marker genes and genes coding quantitative traits across a relatively recently (< 9000 years) colonized environmental gradient. In particular, they give evidence for natural selection being the primary agent behind the observed latitudinal differentiation in quantitative traits.  相似文献   

12.
Ecological and life history characteristics such as population size, dispersal pattern, and mating system mediate the influence of genetic drift and gene flow on population subdivision. Bull trout (Salvelinus confluentus) and mountain whitefish (Prosopium williamsoni) differ markedly in spawning location, population size and mating system. Based on these differences, we predicted that bull trout would have reduced genetic variation within and greater differentiation among populations compared with mountain whitefish. To test this hypothesis, we used microsatellite markers to determine patterns of genetic divergence for each species in the Clark Fork River, Montana, USA. As predicted, bull trout had a much greater proportion of genetic variation partitioned among populations than mountain whitefish. Among all sites, FST was seven times greater for bull trout (FST = 0.304 for bull trout, 0.042 for mountain whitefish. After removing genetically differentiated high mountain lake sites for each species FST, was 10 times greater for bull trout (FST = 0.176 for bull trout; FST = 0.018 for mountain whitefish). The same characteristics that affect dispersal patterns in these species also lead to predictions about the amount and scale of adaptive divergence among populations. We provide a theoretical framework that incorporates variation in ecological and life history factors, neutral divergence, and adaptive divergence to interpret how neutral and adaptive divergence might be correlates of ecological and life history factors.  相似文献   

13.
In the Southwestern Atlantic Ocean, humpback whales migrate every winter to the Brazilian coast for breeding and calving in the Abrolhos Bank. This breeding stock represents the remnants of a larger population heavily exploited during the beginning of the 20th century. Despite its relevance to conservation efforts, the degree of current genetic variation and the migratory relationship with Antarctic feeding areas for this population are still largely unknown. To examine these questions, we sequenced ∼400 bp of the mitochondrial DNA control region from samples taken off the Brazilian coast (n = 171) and near the Antarctic Peninsula (n = 77). The genetic variability of the Brazilian humpback whale breeding population was high and similar to that found in other Southern Hemisphere breeding grounds. Phylogenetic analysis suggested the existence of a new mitochondrial clade that exists at low frequency among Southern Hemisphere populations. Direct comparison between the Brazilian and the Colombia breeding populations and the Antarctic Peninsula feeding population showed no genetic differentiation between this feeding region and the Colombian breeding area or between feeding Areas I and II near the Antarctic Peninsula. In contrast, these populations were genetically distinct from the Brazilian population. Two humpback whales sampled off South Georgia Islands, in the Scotia Sea, shared identical haplotypes to whales from Brazil. Our results, supported by photo-identification and satellite telemetry data, suggest that the main feeding area of the Southern Hemisphere humpback whale population is likely to be located near the South Georgia/South Sandwich Islands area and not in the Antarctic Peninsula.  相似文献   

14.
Skeletal remains of baleen whales killed during the onset of 20th century commercial whaling lie scattered across the shores and abandoned whaling stations of the subantarctic island of South Georgia. Here we report on genetic species identification of whale bones collected from South Georgia using standard historical DNA protocols. We amplified and sequenced short fragments of the mitochondrial DNA (mtDNA) control region from 281 available bone samples. Of these, 231 provided mtDNA sequences of sufficient quality and length (174–194 bp) for species identification: 158 bones were identified as humpback whale (Megaptera novaeangliae), 51 bones were identified as fin whale (Balaenoptera physalus), 18 bones were identified as blue whale (B. musculus), two bones were identified as sei whale (B. borealis), one bone was identified as a southern right whale (Eubalaena australis), and one bone was identified as a southern elephant seal (Mirounga leonina). The prominence of humpback, fin, and blue whale bones in the sample collection corresponds to the catch record of the early years of whaling on the island of South Georgia (pre‐1915), prior to the depletion of these populations.  相似文献   

15.
For neutral, additive quantitative characters, the amount of additive genetic variance within and among populations is predictable from Wright's FST, the effective population size and the mutational variance. The structure of quantitative genetic variance in a subdivided metapopulation can be predicted from results from coalescent theory, thereby allowing single-locus results to predict quantitative genetic processes. The expected total amount of additive genetic variance in a metapopulation of diploid individual is given by 2Ne sigma m2 (1 + FST), where FST is Wright's among-population fixation index, Ne is the eigenvalue effective size of the metapopulation, and sigma m2 is the mutational variance. The expected additive genetic variance within populations is given by 2Ne sigma e2(1-FST), and the variance among demes is given by 4FSTNe sigma m2. These results are general with respect to the types of population structure involved. Furthermore, the dimensionless measure of the quantitative genetic variance among populations, QST, is shown to be generally equal to FST for the neutral additive model. Thus, for all population structures, a value of QST greater than FST for neutral loci is evidence for spatially divergent evolution by natural selection.  相似文献   

16.
The krill surplus hypothesis of unlimited prey resources available for Antarctic predators due to commercial whaling in the 20th century has remained largely untested since the 1970s. Rapid warming of the Western Antarctic Peninsula (WAP) over the past 50 years has resulted in decreased seasonal ice cover and a reduction of krill. The latter is being exacerbated by a commercial krill fishery in the region. Despite this, humpback whale populations have increased but may be at a threshold for growth based on these human-induced changes. Understanding how climate-mediated variation in prey availability influences humpback whale population dynamics is critical for focused management and conservation actions. Using an 8-year dataset (2013–2020), we show that inter-annual humpback whale pregnancy rates, as determined from skin-blubber biopsy samples (n = 616), are positively correlated with krill availability and fluctuations in ice cover in the previous year. Pregnancy rates showed significant inter-annual variability, between 29% and 86%. Our results indicate that krill availability is in fact limiting and affecting reproductive rates, in contrast to the krill surplus hypothesis. This suggests that this population of humpback whales may be at a threshold for population growth due to prey limitations. As a result, continued warming and increased fishing along the WAP, which continue to reduce krill stocks, will likely impact this humpback whale population and other krill predators in the region. Humpback whales are sentinel species of ecosystem health, and changes in pregnancy rates can provide quantifiable signals of the impact of environmental change at the population level. Our findings must be considered paramount in developing new and more restrictive conservation and management plans for the Antarctic marine ecosystem and minimizing the negative impacts of human activities in the region.  相似文献   

17.
We estimated humpback and blue whale abundance from 1991 to 1997 off the west coast of the U. S. and Mexico comparing capture-recapture models based on photographically identified animals and line-transect methods from ship-based surveys. During photo-identification research we obtained 4,212 identifications of 824 humpback whales and 2,403 identifications of 908 blue whales primarily through non-systematic small-boat surveys along the coast of California, Oregon, and Washington. Line-transect surveys from NOAA ships in 1991, 1993, and 1996 covered approximately 39,000 km along the coast of Baja California, California, Oregon, and Washington out to 555 km from shore. The nearshore and clumped distribution of humpback whales allowed photographic identification from small boats to cost-effectively sample a substantial portion of the population, but made it difficult to obtain effective samples in the line-transect surveys covering broad areas. The humpback capture-recapture estimates indicated humpback whale abundance increased over the six years (from 569 to 837). The broader more offshore distribution of blue whales made it harder to obtain a representative sample of identification photographs, but was well suited to the line-transect estimates. The line-transect estimates, after correction for missed animals, indicated approximately 3,000 blue whales (CV = 0.14). Capture-recapture estimates of blue whales were lower than this: approximately 2,000 when using photographs obtained from the line-transect surveys as one of the samples. Comparison of the results from the two methods provides validation, as well as insight into potential biases associated with each method.  相似文献   

18.
We assessed the effects of long-term habitat fragmentation on genetic (random amplified polymorphic DNA) diversity in 11 Peromyscus maniculatus populations in the Lake Superior watershed. We analysed genetic structure at two spatial scales and the effect of island size and isolation on genetic diversity. At the regional scale, island populations differed from mainland populations (FST = 0.36), but mainland populations did not differ from each other (FST = 0.01). At the local scale, populations of the main island of Isle Royale differed from adjacent islet populations (P < 0.001; Monte Carlo approximation of Fisher's exact test), but not from each other (combined P = 0.63). Although geographical distance and genetic distance were positively correlated (P < 0.01; Mantel test), cluster analysis revealed some inconsistencies. Finally, genetic diversity was inversely related to isolation (P = 0.01), but had an unexpectedly negative relationship with island area (P = 0.03). The genetic structure of P. maniculatus populations in portions of the Lake Superior watershed appears to have been affected by long-term habitat fragmentation.  相似文献   

19.
Understanding the population structure of a species is critical to its effective management and conservation. The humpback whale ( Megaptera novaeangliae ) has been the target of numerous research projects in several ocean basins, but no clear picture of its population structure has emerged. In the North Atlantic Ocean, genetic analyses and photo-identification movements have shown significant heterogeneity among the summer feeding grounds. Building on this knowledge, we test the hypothesis that the feeding grounds represent distinct populations by analyzing the spatial pattern of summer humpback whale sightings and survey effort. Controlling for the spatial pattern of effort, sightings are clustered, with peaks at radial distances of 300 km, 600 km, and 1,500 km. These results provide insight into the spatial extent of the summer population structure of humpback whales in the North Atlantic Ocean. Fine-scale clustering at distances of 300 km and 600 km is compatible with multiple populations consisting of the Gulf of Maine, eastern Canada, western Greenland, and Iceland. Broad-scale clustering at distances of 1,500 km may represent divisions between the western and eastern North Atlantic populations. These results provide spatial bounds to the feeding grounds of humpback whales and emphasize their distinct nature as management units.  相似文献   

20.
Gao LZ 《Molecular ecology》2005,14(14):4287-4297
Oryza officinalis Wall. ex Watt. is an agriculturally important but seriously endangered species of wild rice. To obtain more accurate estimates of population structure for improved conservation planning of the species, genetic variability at 14 microsatellite DNA loci was examined in population samples covering most of the species' range in China. Considerable genetic variability (overall Na = 1.886, P = 62%, HO = 0.056, HE = 0.216, and HS = 0.277) was detected at the 14 loci in 442 individuals of the 18 natural populations. The evaluation of partitioning of genetic variability (FST = 0.442) suggested high genetic differentiation among the Chinese O. officinalis populations. An overall value of Nm = 0.316 suggested limited gene flow occurred among the sampled populations. Most of the populations showed heterozygote deficits in tests of Hardy-Weinberg equilibrium and significantly positive FIS values. This could be due to some inbreeding occurring in this predominantly outcrossing species. For effective in situ conservation and restoration genetics, maintenance of significant historical processes is particularly important, including high outbreeding, considerable gene flow, and large population effective sizes. The high FST values detected among populations in this study are instructive for adopting a conservation plan that includes representative populations with the greatest genetic variation for either in situ conservation management or germplasm collection expeditions.  相似文献   

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