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1.
Genetic differentiation in 20 hierarchically sampled populations of wild barley was analyzed with quantitative traits, allozymes and Random Amplified Polymorphic DNAs (RAPDs), and compared for three marker types at two hierarchical levels. Regional subdivision for both molecular markers was much lower than for quantitative traits. For both allozymes and RAPDs, most loci exhibited minor or no regional differentiation, and the relatively high overall estimates of the latter were due to several loci with exceptionally high regional differentiation. The allozyme- and RAPD-specific patterns of differentiation were concordant in general with one another, but not with quantitative trait differentiation. Divergent selection on quantitative traits inferred from very high regional Q(ST) was in full agreement with our previous results obtained from a test of local adaptation and multilevel selection analysis. In contrast, most variation in allozyme and RAPD variation was neutral, although several allozyme loci and RAPD markers were exceptional in their levels of regional differentiation. However, it is not possible to answer the question whether these exceptional loci are directly involved in the response to selection pressure or merely linked to the selected loci. The fact that Q(ST) and F(ST) did not differ at the population scale, that is, within regions, but differed at the regional scale, for which local adaptation has been previously shown, implies that comparison of the level of subdivision in quantitative traits, as compared with molecular markers, is indicative of adaptive population differentiation only when sampling is carried out at the appropriate scale. 相似文献
2.
Thirteen allozyme loci and 68 random amplified polymorphic DNA (RAPD) markers were analyzed to assess the genetic diversity and population structure of threatened Antirrhinum microphyllum (Scrophulariaceae), a narrow endemic of central Spain known from only four populations. According to allozyme data, species genetic diversity (p = 46.15%, A = 2.61, and H(e) = 0.218), as well as within-population genetic diversity (p = 44.23%, A = 2.10, and H(e) = 0.204), were high when compared to average estimates for other narrowly distributed plant species. Ninety-four percent of species genetic diversity corresponded to within-population genetic diversity. Nevertheless, significant differences were found among populations in allele frequencies of four of the six polymorphic loci, and three private alleles were detected. Inbreeding coefficients (F(IS)) suggest that populations are structured in genetic neighborhoods. The RAPDs also showed high levels of genetic diversity (p = 89.71% and H(e) = 0.188 at the species level, and p = 67.65% and H(e) = 0.171 at the population level). Nei's genetic distances estimated both from allozymes and RAPDs indicated low differentiation among populations. In spite of this, the low frequencies of certain alleles and the presence of private alleles indicate that efforts should be made to conserve all four remaining populations. 相似文献
3.
Random amplified polymorphic DNA (RAPD) and quantitative trait variation of the widespread and ephemeral Senecio gallicus were surveyed in 11 populations sampled from the Iberian Peninsula and southern France. The aim of the study was to compare population relationships and levels of geographical differentiation with chloroplast (cp) DNA and allozyme variation assessed previously in the same populations. Employing multivariate statistics, a moderate level of intraspecific differentiation was observed among populations from Iberian coastal and inland regions for both RAPDs and quantitative traits. However, RAPDs provided greater resolution in identifying additional population structure within the hypothesized, Pleistocene refugial source area of the species in coastal Iberia. A major part of the geographical subdivision in RAPD and quantitative traits was concordant with the coastal vs. inland divergence as previously inferred from cpDNA haplotype frequencies, but strongly contrasted with the geographical uniformity of the species for allozymes. This concordance across various nuclear and cytoplasmic markers (RAPDs/quantitative traits, cpDNA) suggests that geographical uniformity for allozymes is more attributable to low rates of evolution and/or small genome sampling rather than high rates of pollen dispersal, slow rates of nuclear lineage sorting, or indirect balancing selection. The present study underscores the value of using additional classes of nuclear markers for narrowing the numbers of competing causal hypotheses about intraspecific cpDNA-allozyme discrepancies and their underlying evolutionary processes. 相似文献
4.
Insights into processes that lead to the distribution of genetic variation within plant species require recognition of the importance of both pollen and seed movement. Here we investigate the contributions of pollen and seed movement to overall gene flow in the Central American epiphytic orchid, Laelia rubescens. Genetic diversity and structure were examined at multiple spatial scales in the tropical dry forest of Costa Rica using nuclear (allozymes) and chloroplast restriction fragment length polymorphism (RFLP) markers, which were found to be diverse (allozymes, P = 73.3%; HE = 0.174; cpDNA, HE = 0.741). Nuclear genetic structure (FSTn) was low at every spatial scale (0.005-0.091). Chloroplast markers displayed more structure (0.073-0.254) but relatively similar patterns. Neither genome displayed significant isolation-by-distance. Pollen and seed dispersal rates did not differ significantly from one another (mp/ms = 1.40) at the broadest geographical scale, among sites throughout Costa Rica. However, relative contributions of pollen and seeds to gene flow were scale-dependent, with different mechanisms determining the dominant mode of gene flow at different spatial scales. Much seed dispersal is highly localized within the maternal population, while some seeds enter the air column and are dispersed over considerable distances. At the intermediate scale (10s to 100s of metres) pollinators are responsible for substantial pollen flow. This species appears capable of distributing its genes across the anthropogenically altered landscape that now characterizes its Costa Rican dry forest habitat. 相似文献
5.
Tyrone Ridgway 《Biodiversity and Conservation》2005,14(1):135-149
Understanding genetic variability and gene flow between populations of scleractinian corals separated by one to several hundred kilometers is crucially important as we head into a century of climate change in which an understanding of the connectivity of populations is a critically important question in management. Genetic methods that directly use molecular variance in the DNA should offer greater precision in detecting differences among individuals and populations than the more traditional allozyme electrophoresis. However, this paper highlights the point that the limited number of DNA markers that have been identified for scleractinian coral genetic studies do not necessarily offer greater precision than that offered by allozymes. In fact, at present allozyme electrophoresis yields greater information than the eight different DNA markers used in this study. Given the relative ease of use of allozymes and the wealth of comparable data sets from numerous previously published studies, allozyme electrophoresis should not be dismissed for population structure and connectivity studies on coral reefs. While continued effort should be placed into searching for new DNA markers, until a more sensitive DNA marker becomes available for scleractinian corals, allozyme electrophoresis remains a powerful and relevant technique for understanding the connectivity of coral population studies. 相似文献
6.
The clonal and population structure of a rare endemic plant, Wyethia reticulata (Asteraceae): allozyme and RAPD analysis 总被引:3,自引:0,他引:3
Genetic structure arises when limited gene flow between populations favours the development of distinct arrays of genetic characters within each population. Determining the spatial scale at which this differentiation occurs is critical to our understanding of population biology and microevolution of species. The genetic structure and spatial pattern of genetic variation in an endemic, clonal perennial, Wyethia reticulata E. Greene, was investigated using random amplified polymorphic DNA (RAPD) markers and allozyme alleles. Large stands (250–360 m2 ) were found to contain few genetic individuals. Despite the small population sizes and endemism of the species, W. reticulata was highly diverse genetically, with most of the variation (75–81%) distributed within populations. A population structure in full agreement with spatially defined populations was achieved only by combining RAPD and allozyme markers. Analysis using both types of markers appeared to provide estimates of genetic similarity between individuals that were most consistent with empirical data on plant distributions. We postulated that large, long-lived clones dominated genetic relationships within populations but also provided opportunities for gene flow between populations on a longer time scale. The two marker types yielded different estimates of between-individual similarity and revealed disparate patterns of population structure. This result will arise because allozymes and random DNA segments have dissimilar evolutionary dynamics with respect to mutation and selection. 相似文献
7.
K G Ross D D Shoemaker M J Krieger C J DeHeer L Keller 《Molecular biology and evolution》1999,16(4):525-543
We used 30 genetic markers of 6 different classes to describe hierarchical genetic structure in introduced populations of the fire ant Solenopsis invicta. These included four classes of presumably neutral nuclear loci (allozymes, codominant random amplified polymorphic DNAs (RAPDs), microsatellites, and dominant RAPDs), a class comprising two linked protein-coding nuclear loci under selection, and a marker of the mitochondrial DNA (mtDNA). Patterns of structure revealed by F statistics and exact tests of differentiation were highly concordant among the four classes of neutral nuclear markers, although the microsatellites were the most effective markers for detecting structure. The results from the mtDNA complemented those from the neutral nuclear markers by revealing that strong limitations to female-mediated gene flow were the cause of the local structure registered by the nuclear markers. The pattern of structure inferred from the selected nuclear loci was markedly different from the patterns derived from the other sets of markers but was predictable on the basis of the presumed mode of selection acting on these loci. In general, the results for all six classes of markers can be explained by known features of the social and reproductive biology of fire ants. Thus, the results from these diverse sets of markers, combined with detailed natural history data, provide an unusually complete picture of how the fundamental evolutionary forces of gene flow, drift, and selection govern the distribution of genetic variation within and between fire ant populations. 相似文献
8.
羊草种群遗传分化的RAPD分析Ⅱ.RAPD数据的统计分析 总被引:9,自引:4,他引:5
对松嫩草原上分布的灰绿型和黄绿型羊草9个种群进行了15个引物的RAPD分析,统计结果表明,两类种群的扩增片段数和多态位点比率明显不同,黄绿型种群低于灰绿型,其值分别<90与>100,<50%与>70%,比较了7种不同统计方法据RAPD表型或基因型频率估算的种群遗传多样性,几种统计结果都揭示,黄绿型种群低于灰绿型种群,用F1s值矫正种群对Hardy-Weinberg平衡的偏离后,估算等位基因频率,通过Shannon指数和Nei指数估计羊草种群间分化分别为37.6%和35.7%,高于等位酶的分析,讨论比较了等位酶和RAPD分析结果的异同。 相似文献
9.
Genetic variation at allozyme and RAPD loci in sessile oak Quercus petraea (Matt.) Liebl.: the role of history and geography 总被引:7,自引:0,他引:7
The nuclear genetic variation within and among 21 populations of sessile oak was estimated at 31 RAPD loci in conjunction with previous estimates of variation at eight allozyme loci. The aim of the study was to assess the relative role of isolation-by-distance and postglacial history on patterns of nuclear variation. Because of its small effective population size and maternal transmission, the chloroplast genome is a good marker of population history. Both kinds of nuclear variation (RAPD and allozyme) were therefore compared, first, to the geographical distances among populations and, secondly, to chloroplast DNA restriction polymorphism in the same populations. Multiple Mantel tests were used for this purpose. Although RAPDs revealed less genetic diversity than allozymes, levels of genetic differentiation ( G ST ) were identical. The standard genetic distance calculated at all RAPD loci was correlated with geographical distances but not with the genetic distance calculated from chloroplast DNA data. Conversely, allozyme variation was correlated with chloroplast DNA variation, but not with geography. Possibly, divergent selection at two allozyme loci during the glacial period could explain this pattern. Because of its greater number of loci assayed, RAPDs probably provided a less biased picture of the relative role of geography and history. 相似文献
10.
Patterns of variation in quantitative characters and genetic markers were compared among six regional populations of white spruce [Picea glauca (Moench) Voss]. Although some phenotypic characters were correlated with latitude (r = 0.791), longitude (r = -0.796) and precipitation during the growing season (r = 0.789), variability at genetic markers was not correlated with geographical or bioclimatic variables, and followed neutral expectations. Estimates of genetic diversity and population differentiation for 14 allozymes (translated regions of coding genes) were essentially indistinguishable from those observed for 11 expressed sequence tag polymorphisms (ESTPs) from untranslated regions of coding genes. Variation among populations for quantitative traits such as eighth year height (Q(ST) = 0.082), thirteenth year height (Q(ST) = 0.069), total wood density (Q(ST) = 0.102) and date of budset (Q(ST) = 0.246), was greater than for allozymes (G(ST) = 0.014) and ESTPs (G(ST) = 0.019). These trends suggest a strong adaptive response in quantitative traits, contrasting to allozymes and ESTPs where no selective response could be detected and where populations appeared to be essentially in a migration-drift equilibrium. 相似文献
11.
Z. Münzbergová S. A. O. Cousins T. Herben I. Plačková M. Mildén J. Ehrlén 《Plant biology (Stuttgart, Germany)》2013,15(1):195-202
Many recent studies have explored the effects of present and past landscape structure on species distribution and diversity. However, we know little about the effects of past landscape structure on distribution of genetic diversity within and between populations of a single species. Here we describe the relationship between present and past landscape structure (landscape connectivity and habitat size estimated from historical maps) and current genetic structure in a perennial herb, Succisa pratensis. We used allozymes as co‐dominant markers to estimate genetic diversity and deviation from Hardy–Weinberg equilibrium in 31 populations distributed within a 5 km2 agricultural landscape. The results showed that current genetic diversity of populations was related to habitat suitability, habitat age, habitat size and habitat connectivity in the past. The effects of habitat age and past connectivity on genetic diversity were in most cases also significant after taking the current landscape structure into account. Moreover, current genetic similarity between populations was affected by past connectivity after accounting for current landscape structure. In both cases, the oldest time layer (1850) was the most informative. Most populations showed heterozygote excess, indicating disequilibrium due to recent gene flow or selection against homozygotes. These results suggest that habitat age and past connectivity are important determinants of distribution of genetic diversity between populations at a scale of a few kilometres. Landscape history may significantly contribute to our understanding of distribution of current genetic structure within species and the genetic structure may be used to better understand landscape history, even at a small scale. 相似文献
12.
Apostolos P. Apostolidis Katerina A. Moutou Costas Stamatis Zissis Mamuris 《Biologia》2009,64(5):1005-1010
In the present work we used three molecular techniques (allozymes, RAPDs and mtDNA RFLPs) in order to study the genetic structure
of three commercial marine species (Mullus surmuletus, Mullus barbatus, and Pagellus erythrinus). Each species was sampled from three locations within the Gulf of Pagasitikos, Greece and from two neighbouring locations
outside the Gulf (Trikeri and Alonissos). Values of genetic heterozygosity and nucleotide diversity for all populations studied
were similar or above the mean values observed in marine fishes. None of the three types of molecular markers used revealed
diagnostic patterns, which could allow the allocation of individuals to one of the populations. The analyses revealed that
the three populations within Pagasitikos were homogenous representing thus a panmictic stock. However, there were evidences
of genetic population subdivision between localities from inside and outside of the Pagasitikos Gulf. The results provide
essential information for the design of a sustainable management plan of the Gulf of Pagasitikos and its demersal fish resources. 相似文献
13.
Curt L. Elderkin Edward J. Perkins Paul L. Leberg Paul L. Klerks Richard F. Lance 《Freshwater Biology》2004,49(11):1487-1494
1. We predicted that zebra mussel, Dreissena polymorpha (Pallas), genetic structure in the Mississippi River would follow a model of invasive species genetics, which predicts low genetic structure among populations of recently established species. This prediction was upheld in our previous genetic study using allozymes, however, one locus yielded anomalous results. 2. We employed amplified fragment length polymorphism (AFLP) analysis as a neutral marker to assess the amount of genetic structure within and among populations, and as a test of expected population structure from both invasion genetic theory, and the results from our previous study. 3. There was greater spatial differentiation, as measured by Fst, observed using AFLP's than for allozymes (P < 0.001). There was no evidence that AFLP variation conformed to an isolation by distance model, and genetic relationships of populations, as measured by AFLP markers, were not similar to those detected in our allozyme survey. 4. The lack of concordance between these two genetic marker systems probably reflects their differential responses to drift, migration, and selection occurring during this rapid invasion. Strong population structure is counter to predictions that populations of invasive species will not be differentiated, as with observations based on allozyme markers. Therefore, newly established species may require genetic surveys using multiple marker systems to evaluate population structure. 相似文献
14.
Evolutionary implications of allozyme and RAPD variation in diploid populations of dioecious buffalograss Buchloë dactyloides 总被引:1,自引:0,他引:1
Buffalograss, Buchloë dactyloides, is widely distributed throughout the Great Plains of North America, where it is an important species for rangeland forage and soil conservation. The species consists of two widespread polyploid races, with narrowly endemic diploid populations known from two regions: central Mexico and Gulf Coast Texas. We describe and compare the patterns of allozyme and RAPD variation in the two diploid races, using a set of 48 individuals from Texas and Mexico (four population samples of 12 individuals each). Twelve of 22 allozyme loci were polymorphic, exhibiting 35 alleles, while seven 10-mer RAPD primers revealed 98 polymorphic bands. Strong regional differences were detected in the extent of allozyme polymorphism: Mexican populations exhibited more internal gene diversity (He= 0.20, 0.19) than did the Texan populations (He= 0.08, 0.06), although the number of RAPD bands in Texas (n= 62) was only marginally smaller than in Mexico (n= 68). F-statistics for the allozyme data, averaged over loci, revealed strong regional differentiation (mean FRT=+ 0.30), as well as some differentiation among populations within regions (mean FPR=+ 0.09). In order to describe and compare the partitioning of genetic variation for multiple allozyme and RAPD loci, we performed an Analysis of Molecular Variance (AMOVA). AMOVA for both allozyme and RAPD data revealed similar qualitative patterns: large regional differences and smaller (but significant) population differences within regions. RAPDs revealed greater variation among regions (58.4% of total variance) than allozymes (45.2%), but less variation among individuals within populations (31.9% for RAPDs vs. 45.2% for allozymes); the proportion of genetic variance among populations within regions was similar (9.7% for RAPDs vs. 9.6% for allozymes). Despite this large-scale concordance of allozyme and RAPD variation patterns, multiple correlation Mantel techniques revealed that the correlations were low on an individual by individual basis. Our findings of strong regional differences among the diploid races will facilitate further study of polyploid evolution in buffalograss. 相似文献
15.
The conservation of a crop's wild relatives as genetic resources requires an understanding of the way genetic diversity is maintained in their populations, notably the effect of crop-to-wild gene flow. In this study, the amount of differentiation between natural and cultivated populations of Medicago sativa was analysed using random amplified polymorphic DNA (RAPD) markers and an extension of the AMOVA procedure adapted to autotetraploid organisms. Simulations of structured populations were performed to test whether AMOVA provides estimates of population structure in autotetraploids that can be directly compared to those obtained for allozyme data. Simulations showed that straight phi-statistics allow a good estimation of population differentiation when unbiased allelic frequencies are used to correct the conditional expectations of squared genetic distances. But such unbiased estimates can not be practically guaranteed, and population structure is notably overestimated when some populations are fixed for the presence of amplified fragments. However, removing fixed loci from the data set improves the statistical power of the test for population structure. The genetic variation of 15 natural and six cultivated populations of M. sativa was analysed at 25 RAPD loci and compared to estimates computed with allozymes on the same set of populations. Although RAPD markers revealed less within-population genetic diversity than allozymes, the quantitative and qualitative patterns of population structure were in full agreement with allozymes. This confirmed the conclusions drawn from the allozymic survey: crop-to-wild gene flow occurred in many locations, but some other mechanisms opposed cultivated traits to be maintained into natural populations. 相似文献
16.
Eric Routman 《Journal of evolutionary biology》1993,6(3):329-357
Genetic relationships, population subdivision and genetic diversity were estimated from mtDNA and allozyme data for two subspecies of tiger salamander, one of which is obligately metamorphic and the other polymorphic for paedomorphosis (larval reproduction). Far greater genetic differentiation exists between subspecies than within subspecies, suggesting that the subspecies have evolved in allopatry. Values of Fst calculated from both mtDNA and allozymes were greater than 0.400 for each subspecies. Significant population subdivision was detected even on a microgeographic scale. This extensive population subdivision indicates that populations can respond to extremely localized selection pressures. In the case of paedomorphosis, populations in permanent water should evolve paedomorphosis as long as the appropriate genes exist. For both mtDNA and allozymes, comparisons of population structure within the polymorphic subspecies and between polymorphic and metamorphic subspecies reveal no discernible effects of paedomorphosis. However, a comparison of paedomorphic and metamorphic populations of the polymorphic subspecies showed significantly higher mtDNA diversity in paedomorphic populations. The discrepancy between the allozyme and mtDNA results may be due to the lower effective population size of mtDNA compared to autosomal genes. 相似文献
17.
T. Fahima G. L. Sun A. Beharav T. Krugman A. Beiles E. Nevo 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(3-4):434-447
Genetic diversity in random amplified polymorphic DNAs (RAPDs) was studied in 110 genotypes of the tetraploid wild progenitor
of wheat, Triticum dicoccoides, from 11 populations sampled in Israel and Turkey. Our results show high level of diversity of RAPD markers in wild wheat
populations in Israel. The ten primers used in this study amplified 59 scorable RAPD loci of which 48 (81.4%) were polymorphic
and 11 monomorphic. RAPD analysis was found to be highly effective in distinguishing genotypes of T. dicoccoides originating from diverse ecogeographical sites in Israel and Turkey, with 95.5% of the 100 genotypes correctly classified
into sites of origin by discriminant analysis based on RAPD genotyping. However, interpopulation genetic distances showed
no association with geographic distance between the population sites of origin, negating a simple isolation by distance model.
Spatial autocorrelation of RAPD frequencies suggests that migration is not influential. Our present RAPD results are non-random
and in agreement with the previously obtained allozyme patterns, although the genetic diversity values obtained with RAPDs
are much higher than the allozyme values. Significant correlates of RAPD markers with various climatic and soil factors suggest
that, as in the case of allozymes, natural selection causes adaptive RAPD ecogeographical differentiation. The results obtained
suggest that RAPD markers are useful for the estimation of genetic diversity in wild material of T. dicoccoides and the identification of suitable parents for the development of mapping populations for the tagging of agronomically important
traits derived from T. dicoccoides.
Received: 13 July 1998 / Accepted: 13 August 1998 相似文献
18.
Population genetic theory for 'traditional' codominant loci showing low levels of allelic diversity (eg allozymes) has been well characterised and evaluated. In contrast, appropriate methods for the analysis of data from more recently developed marker systems are still being refined. For multilocus dominant markers such as amplified fragment length polymorphisms (AFLPs) and randomly amplified polymorphic DNA (RAPDs), the methods of data analysis can be split into two main categories. In population-based approaches, population allele frequencies are compared to obtain some measure of the partitioning of genetic diversity into within- and between-population components. In contrast, individual-based approaches use individual multilocus genotypes as the unit of analysis. Inferences on population processes such as gene flow are based on inter-relationships among individual samples as visualised on phenetic diagrams such as neighbour joining trees. Using a simulation approach coupled with neighbour joining analyses, we show that while the underlying population genetic structure is an important determinant of tree shape in the analysis of dominant data, the number of loci examined also affects the topology. At low levels of population differentiation (eg FST=0.07), mutually exclusive clustering of individuals into their respective populations can occur when sufficiently large numbers of loci are scored (eg 250 loci, typical of many AFLP studies). In contrast, unresolved star-shaped topologies can be recovered at higher levels of population differentiation (FST= >0.15) when lower numbers of loci are employed (eg 50 loci, typical of many RAPD studies). Thus, the relationship between tree topology and the extent of genetic structuring of populations is contingent upon the number of dominant loci scored. The consequences of these findings for the biological interpretation of individual-based analysis of dominant data sets are discussed. 相似文献
19.
1. Flow regime and riverine architecture are two important landscape characteristics that influence genetic diversity and gene flow in riverine species.
2. Using population genetic markers (mtDNA, microsatellites and allozymes), this study aimed to investigate genetic diversity and gene flow in the freshwater fish, Neosilurus hyrtlii , across two major drainage divisions in northern and central Australia (the Gulf of Carpentaria and Lake Eyre basins). These basins lie adjacent to each other and differ in their hydrological inputs and riverine structure, providing an ideal opportunity to identify the impact of landscape processes upon population dynamics of freshwater fish.
3. Populations were strongly structured among basins, among catchments within basins and were weakly structured within catchments in the Lake Eyre Basin, providing support for the Stream Hierarchy Model.
4. Interestingly, mtDNA and microsatellite diversity was much higher in the Gulf of Carpentaria Basin compared to the Lake Eyre Basin. It was concluded that this difference was due to the extreme hydrological variability in this basin and boom-bust population cycles resulting in smaller effective population sizes in the Lake Eyre Basin. 相似文献
2. Using population genetic markers (mtDNA, microsatellites and allozymes), this study aimed to investigate genetic diversity and gene flow in the freshwater fish, Neosilurus hyrtlii , across two major drainage divisions in northern and central Australia (the Gulf of Carpentaria and Lake Eyre basins). These basins lie adjacent to each other and differ in their hydrological inputs and riverine structure, providing an ideal opportunity to identify the impact of landscape processes upon population dynamics of freshwater fish.
3. Populations were strongly structured among basins, among catchments within basins and were weakly structured within catchments in the Lake Eyre Basin, providing support for the Stream Hierarchy Model.
4. Interestingly, mtDNA and microsatellite diversity was much higher in the Gulf of Carpentaria Basin compared to the Lake Eyre Basin. It was concluded that this difference was due to the extreme hydrological variability in this basin and boom-bust population cycles resulting in smaller effective population sizes in the Lake Eyre Basin. 相似文献
20.
JULIE A. LEE-YAW REW DAVIDSON† BRAD H. MCRAE‡ DAVID M. GREEN§ 《Molecular ecology》2009,18(9):1863-1874
Understanding factors that influence population connectivity and the spatial distribution of genetic variation is a major goal in molecular ecology. Improvements in the availability of high-resolution geographic data have made it increasingly possible to quantify the effects of landscape features on dispersal and genetic structure. However, most studies examining such landscape effects have been conducted at very fine (e.g. landscape genetics) or broad (e.g. phylogeography) spatial scales. Thus, the extent to which processes operating at fine spatial scales are linked to patterns at larger scales remains unclear. Here, we test whether factors impacting wood frog dispersal at fine spatial scales are correlated with genetic structure at regional scales. Using recently developed methods borrowed from electrical circuit theory, we generated landscape resistance matrices among wood frog populations in eastern North America based on slope, a wetness index, land cover and absolute barriers to wood frog dispersal. We then determined whether these matrices are correlated with genetic structure based on six microsatellite markers and whether such correlations outperform a landscape-free model of isolation by resistance. We observed significant genetic structure at regional spatial scales. However, topography and landscape variables associated with the intervening habitat between sites provide little explanation for patterns of genetic structure. Instead, absolute dispersal barriers appear to be the best predictor of regional genetic structure in this species. Our results suggest that landscape variables that influence dispersal, microhabitat selection and population structure at fine spatial scales do not necessarily explain patterns of genetic structure at broader scales. 相似文献