Population structure and colour variation of the cichlid fishes Labeotropheus fuelleborni Ahl along a recently formed archipelago of rocky habitat patches in southern Lake Malawi

Extremely fine-scale genetic partitioning has recently been detected among populations of Lake Malawi''s rock-dwelling cichlids through the study of microsatellite loci. Understanding the mechanisms of genetic differentiation that operate in this rapidly speciating group requires further investigation of the geographic patterns of gene flow and the congruence between morphological and genetic divergence. In pursuit of this goal, genetic variation at four microsatellite loci and variation in male breeding coloration were examined in several populations of Labeotropheus fuelleborni from southern Lake Malawi. Significant genetic differentiation exists among populations (overall F_ST = 0.063; p = 0.0002). While migration appears unrestricted within continuous rocky patches, deep waters and sandy bays more than 2 km wide act as strong barriers to gene flow. Dispersal of L. fuelleborni appears to follow a stepping-stone model in which the distribution of habitats often constrains migration to one dimension. It is hypothesized that clinal colour variation in the study area has resulted from the secondary contact of divergent lineages, although reproductive isolation between colour variants is not apparent. Relative to shoreline populations, reduced levels of gene flow among populations inhabiting isolated, deep-water islands provides greater opportunities for drift, adaptation to local conditions, or sexual selection to effect genetic differentiation in this species.     

The coupling hypothesis: why genome scans may fail to map local adaptation genes

Genomic scans of multiple populations often reveal marker loci with greatly increased differentiation between populations. Often this differentiation coincides in space with contrasts in ecological factors, forming a genetic-environment association (GEA). GEAs imply a role for local adaptation, and so it is tempting to conclude that the strongly differentiated markers are themselves under ecologically based divergent selection, or are closely linked to loci under such selection. Here, we highlight an alternative and neglected explanation: intrinsic (i.e. environment-independent) pre- or post-zygotic genetic incompatibilities rather than local adaptation can be responsible for increased differentiation. Intrinsic genetic incompatibilities create endogenous barriers to gene flow, also known as tension zones, whose location can shift over time. However, tension zones have a tendency to become trapped by, and therefore to coincide with, exogenous barriers due to ecological selection. This coupling of endogenous and exogenous barriers can occur easily in spatially subdivided populations, even if the loci involved are unlinked. The result is that local adaptation explains where genetic breaks are positioned, but not necessarily their existence, which can be best explained by endogenous incompatibilities. More precisely, we show that (i) the coupling of endogenous and exogenous barriers can easily occur even when ecological selection is weak; (ii) when environmental heterogeneity is fine-grained, GEAs can emerge at incompatibility loci, but only locally, in places where habitats and gene pools are sufficiently intermingled to maintain linkage disequilibria between genetic incompatibilities, local-adaptation genes and neutral loci. Furthermore, the association between the locally adapted and intrinsically incompatible alleles (i.e. the sign of linkage disequilibrium between endogenous and exogenous loci) is arbitrary and can form in either direction. Reviewing results from the literature, we find that many predictions of our model are supported, including endogenous genetic barriers that coincide with environmental boundaries, local GEA in mosaic hybrid zones, and inverted or modified GEAs at distant locations. We argue that endogenous genetic barriers are often more likely than local adaptation to explain the majority of Fst-outlying loci observed in genome scan approaches - even when these are correlated to environmental variables.     

Genetic consequences of a century of protection: serial founder events and survival of the little spotted kiwi (Apteryx owenii)

We present the outcome of a century of post-bottleneck isolation of a long-lived species, the little spotted kiwi (Apteryx owenii, LSK) and demonstrate that profound genetic consequences can result from protecting few individuals in isolation. LSK were saved from extinction by translocation of five birds from South Island, New Zealand to Kapiti Island 100 years ago. The Kapiti population now numbers some 1200 birds and provides founders for new populations. We used 15 microsatellite loci to compare genetic variation among Kapiti LSK and the populations of Red Mercury, Tiritiri Matangi and Long Islands that were founded with birds from Kapiti. Two LSK native to D''Urville Island were also placed on Long Island. We found extremely low genetic variation and signatures of acute and recent genetic bottleneck effects in all four populations, indicating that LSK have survived multiple genetic bottlenecks. The Long Island population appears to have arisen from a single mating pair from Kapiti, suggesting there is no genetic contribution from D''Urville birds among extant LSK. The N_e/N_C ratio of Kapiti Island LSK (0.03) is exceptionally low for terrestrial vertebrates and suggests that genetic diversity might still be eroding in this population, despite its large census size.     

Microsatellite variation among diverging populations of Drosophila mojavensis

Divergence and speciation may occur by various means, depending on the particular history, selective environments, and genetic composition of populations. In Drosophila mojavensis, a good model of incipient speciation, understanding the population genetic structure within this group facilitates our ability to understand the context in which reproductive isolation among populations is developing. Here we report the genetic structure and relationships of D. mojavensis populations at nuclear loci. We surveyed 29 populations throughout the distribution of D. mojavensis for four microsatellite loci to differentiation among populations of this species. These loci reveal four distinct geographical regions of D. mojavensis populations in the south-western United States and north-western Mexico--(i) Baja California peninsula (Baja), (ii) Sonora, Mexico-southern Arizona, United States (Sonora), (iii) Mojave Desert and Grand Canyon (Mojave), and (iv) Santa Catalina Island (Catalina). While all regions show strong isolation, Mojave and Catalina are highly diverged from other regions. Within any region, populations are largely homogenous over broad geographical distances. Based on the population structure, we find clear geographical barriers to gene flow appear to have a strong effect in isolating populations across regions for this species.     

Incipient ecological speciation between successional varieties of a dominant tree involves intrinsic postzygotic isolating barriers

Whereas disruptive selection imposed by heterogeneous environments can lead to the evolution of extrinsic isolating barriers between diverging populations, the evolution of intrinsic postzygotic barriers through divergent selection is less certain. Long‐lived species such as trees may be especially slow to evolve intrinsic isolating barriers. We examined postpollination reproductive isolating barriers below the species boundary, in an ephemeral hybrid zone between two successional varieties of the landscape‐dominant Hawaiian tree, Metrosideros polymorpha, on volcanically active Hawai'i Island. These archipelago‐wide sympatric varieties show the weakest neutral genetic divergence of any taxon pair on Hawai'i Island but significant morphological and ecological differentiation consistent with adaptation to new and old lava flows. Cross‐fertility between varieties was high and included heterosis of F₁ hybrids at the seed germination stage, consistent with a substantial genetic load apparent within varieties through low self‐fertility and a lack of self‐pollen discrimination. However, a partial, but significant, barrier was observed in the form of reduced female and male fertility of hybrids, especially backcross hybrids, consistent with the accumulation of genetic incompatibilities between varieties. These results suggest that partial intrinsic postzygotic barriers can arise through disruptive selection acting on large, hybridizing populations of a long‐lived species.     

浙江省境内七子花天然种群遗传多样性研究

利用RAPD技术对浙江省境内的七子花9个天然种群遗传多样性和遗传分化进行研究.结果表明,12种随机引物对180棵植物进行检测,共得到164个可重复的位点.多态位点百分率在14.60%～27.44%(平均为20.73%),以括苍山种群最高,其次是四明山种群,最低是观音坪种群.Shannon指数和Nei指数均反映出七子花各种群具有较低的遗传多样性,但遗传分化明显.Shannon指数显示种群内遗传多样性只占总遗传多样性的27.28%,而种群间遗传多样性却占72.72%;Nei指数表明种群内的遗传变异较小,种群间的遗传变异较大,种群间的遗传分化系数为0.7157.七子花种群间的基因流为0.1987,遗传相似度平均为0.7306,遗传距离平均为0.3150,各种群间的遗传分化明显.根据遗传距离聚类分析,大致可以将9个七子花种群分为东部和西部两大类群.     

High levels of genetic polymorphism in the insular endemic herb Jepsonia malvifolia.

Jepsonia malvifolia is a long-lived perennial herb endemic to the Channel Islands of southern California and Guadalupe Island, Mexico. Twelve populations of J. malvifolia on San Clemente Island were surveyed for their genotype at 21 allozyme loci, revealing high levels of genetic polymorphism. For all individuals across San Clemente Island, 95.2% of loci are polymorphic with A(p) = 2.90 and H(e) = 0.179. Populations averaged 60.2% polymorphic loci with A(p) = 2.42 and H(e) = 0.158. Most variation is found within rather than among populations (G(ST) = 0.101), although differentiation among populations is significant. Genetic identities range from 0.936 to 0.999 with mean I = 0.975. There is no significant relationship between genetic and geographic distance. Gene flow among populations is Nm = 9.5 based on private alleles and Nm = 2.2 based on F(ST). Outcrossing rates based on fixation indices average t = 0.753, indicating a primarily outcrossed mating system. The genetic variation observed is unusually high for an insular endemic herb and indicates that J. malvifolia is unlikely to be endangered by genetic factors.     

入侵植物薇甘菊种群的遗传分化

利用简单重复序列区间(Inter simple sequence repeat, ISSR)分子标记技术分析了入侵植物薇甘菊(Mikania micrantha)8个种群的遗传多样性及遗传分化。12个引物共扩增出171个位点,其中多态位点有103个,多态位点百分率(P%)为60.23%,Shannon信息指数(I)为0.281 8,Nei指数(h)为0.184 9,薇甘菊在物种水平具有较高的遗传多样性。AMOVA显示薇甘菊具有较高的遗传分化,36.49%的变异发生在种群间,63.51%的变异发生于种群内,基因分化系数(G_ST)为0.352 4。种群间的基因流较高,为0.918 7。薇甘菊8个种群之间的遗传相似性很高,平均为0.915 5;遗传距离很小,平均为0.088 4。采用UPGMA法对8个种群进行聚类,可以将8个种群分为两大类群,即内伶仃岛为一个类群,而深圳与东莞内陆种群组成另一类群。薇甘菊现有遗传结构的形成与其生活史特性及入侵生态学特性有关。     

Low genetic differentiation among widely separated populations of the pearl oyster Pinctada fucata as revealed by AFLP

Genetic variation within and among five populations of the pearl oyster Pinctada fucata, from China (Daya Bay, Sanya Bay and Beibu Bay), Japan (Mie Prefecture) and Australia (Port Stephens) was studied using AFLP. Three primer pairs generated 184 loci among which 91.8-97.3% is polymorphic. An overall genetic diversity of 0.38 among populations and an average of 0.37 within populations (ranging from 0.35 in Japanese population to 0.39 in Beibu Bay population) were observed. Genetic differentiation among the five populations is low but significant as indicated by pairwise G_ST (0.0079-0.0404). AMOVA further shows that differentiation is significant among the five populations but is not significant at a broader geographical scale, among the three groups of Chinese, Japanese and Australian populations or among the two groups of Australian and north Pacific populations. The low level of genetic differentiation indicated that P. fucata populations in the west Pacific are genetically linked. Among the five populations, the Australian one is more differentiated from the others, based on both pairwise AMOVA and G_ST analyses, and is genetically isolated by distance as indicated by Mantel test. However, genetic differences among the three Chinese populations are not correlated with the geographic distances, suggesting that Hainan Island and Leizhou Peninsula may act as barriers blocking gene flow.     

Long-term effective population sizes, temporal stability of genetic composition and potential for local adaptation in anadromous brown trout (Salmo trutta) populations

We examined the long-term temporal (1910s to 1990s) genetic variation at eight microsatellite DNA loci in brown trout (Salmo trutta L) collected from five anadromous populations in Denmark to assess the long-term stability of genetic composition and to estimate effective population sizes (Ne). Contemporary and historical samples consisted of tissue and archived scales, respectively. Pairwise thetaST estimates, a hierarchical analysis of molecular variance (amova) and multidimensional scaling analysis of pairwise genetic distances between samples revealed much closer genetic relationships among temporal samples from the same populations than among samples from different populations. Estimates of Ne, using a likelihood-based implementation of the temporal method, revealed Ne >or= 500 in two of three populations for which we have historical data. A third population in a small (3 km) river showed Ne >or= 300. Assuming a stepping-stone model of gene flow we considered the relative roles of gene flow, random genetic drift and selection to assess the possibilities for local adaptation. The requirements for local adaptation were fulfilled, but only adaptations resulting from strong selection were expected to occur at the level of individual populations. Adaptations resulting from weak selection were more likely to occur on a regional basis, i.e. encompassing several populations. Ne appears to have declined recently in at least one of the studied populations, and the documented recent declines of many other anadromous brown trout populations may affect the persistence of local adaptation.     

Genetic differentiation of pink salmon oncorhynchus gorbuscha Walbaum in the Asian part of the range

Genetic variation at 19 allozyme (including 11 polymorphic) and 10 microsatellite loci was examined in the population samples of odd- and even-broodline pink salmon from the southern part of Sakhalin Island, Southern Kuril Islands, and the northern coast of the Sea of Okhotsk. The estimates of relative interpopulation component of genetic variation over the allozyme loci, per broodline, were on average 0.43% (GST), while over the microsatellite loci it was 0.26% (the theta(ST) coefficient, F-statistics based on the allele frequency variance), and 0.90% (the rho(ST) coefficient, R-statistics based on the allele size variance). The values of interlinear component constituted 2.34, 0.31, and 1.05% of the total variation, respectively. Using the allozyme loci, statistically significant intralinear heterogeneity was demonstrated among the regions, as well as among the populations of Southern Sakhalin Island. Multivariate scaling based on the allozyme data demonstrated regional clustering of the sample groups, representing certain populations during the spawning run or in different years. Most of the microsatellite loci examined were found to be highly polymorphic (mean heterozygosity > 0.880). The estimates of interlinear, interregional, and interpopulation variation over these loci in terms of theta(ST) values were substantially lower than in terms of rho(ST) values. Regional genetic differentiation, mostly expressed at the allozyme loci among the populations from the northern and southern parts of the Sea of Okhotsk (i.e., between the Sakhalin and Kuril populations), was less expressed at the microsatellite loci. The differentiation between these regions observed can be considered as the evidence in favor of a large-scale isolation by distance characterizing Asian pink salmon. It is suggested that in pink salmon, low genetic differentiation at neutral microsatellite loci can be explained by extremely high heterozygosity,of the loci themselves, as well as by the migration gene exchange among the populations (the estimate of the genetic migration coefficient inferred from the "private" allele data constituted 2.6 to 3.4%), specifically, by the ancient migration exchange, which occurred during postglacial colonization and colonization of the range.     

Intersimple sequence repeat (ISSR) variation in Lactoris fernandeziana (Lactoridaceae), a rare endemic of the Juan Fernández Archipelago, Chile

Sixteen populations and 89 individuals of Lactoris fernandeziana were examined for variation in intersimple sequence repeat (ISSR) banding patterns. The species is a rare endemic of Masatierra Island in the Juan Fernández Archipelago, and is the only member of the endemic family Lactoridaceae. Five populations showed a single genotype whereas the other 11 populations had from two to 16 multilocus genotypes. Over 73% of the ISSR diversity occurred across populations, with only about 27% within populations. Diversity among populations results from the presence of different subsets of loci within each population rather than unique loci within populations; only two populations displayed novel loci, with one and three in each. Levels of differentiation at ISSR loci among populations are not correlated with geographic distance on Masatierra; rather, the pattern of variation is mosaic. The presence of differentiated local populations is concordant with the geitonogamous breeding system of the species and suggests low levels of long distance pollen or seed dispersal. The mosaic pattern of ISSR variation on Masatierra may result, in part, from drift and inbreeding in small populations following fragmentation of a once more continuous distribution of Lactoris with the formation of canyons by erosion. Also, the generation of new ISSR loci by mutation could occur with rare, sporadic gene flow among populations accounting for the mosaic pattern of variation and the paucity of unique alleles within populations. The ISSR results for Lactoris suggest that studies of morphological, ecological and physiological features may elucidate differentiation among populations of L. fernandeziana . Field studies have demonstrated that plants occur both in the dense forest understory and in the full sunlight in forest openings.     

Genetic diversity and genetic structure of Decalobanthus boisianus in Hainan Island,China

Decalobanthus boisianus is a native plant of Hainan Island, China, which has caused considerable damage to tropical forest ecosystems in recent decades. Understanding the genetic diversity and structure of this species can facilitate uncovering the molecular mechanism of its invasive ability. Here, we collected 77 individuals of D. boisianus spanning 8 distribution areas with a gradient of human disturbance intensity (i.e., low, moderate, and high disturbance intensity groups) to assess patterns of genetic diversity and structure using inter simple sequence repeat (ISSR) markers. We found that a total of 220 loci were scored with 13 primers using ISSR methods, and that 198 loci were polymorphic. The genetic diversity of D. boisianus among these eight forests decreased with increasing human disturbance intensity. Over 70% of the total genetic variation was present within populations, while less than 30% of variation was found among populations. There was a high gene flow (1.27) among them due to a lack of effective geographic barriers. The mean Nei's genetic distance of D. boisianus populations was found to be relatively small (i.e., 0.07), and the average genetic similarity of the eight populations was high (i.e., 0.93). Our findings indicate that the genetic diversity of D. boisianus correlated to human disturbance density, and that D. boisianus populations in Hainan Island have frequent gene exchange. We suggest that reduce deforestation to decrease human disturbance may be a good way to prevent the invasion of D. boisianus.     

American marten (Martes americana) in the Pacific Northwest: population differentiation across a landscape fragmented in time and space

American marten (Martes americana) have a close association with mature temperate forests, a habitat that expanded throughout the Pacific Northwest as glaciers receded at the end of the Pleistocene. Similar to several other forest-associated mammals in North America (e.g. black bear), genetic analysis of the marten shows a deep phylogeographical subdivision that reflects populations with distinctive evolutionary histories. Using a suite of 14 microsatellite markers, we explored the genetic structure of marten populations in two reciprocally monophyletic clades in the Pacific Northwest identified previously as M. caurina and M. americana by mitochondrial haplotypes and morphology. Microsatellite phylogeographical patterns were congruent with mitochondrial analyses. These independent data sets shed light upon hybridization patterns, population structure and evolutionary histories. Hybridization between M. caurina and M. americana individuals was documented in two regions of sympatry (Kuiu Island in southeastern Alaska and southern Montana). Northern insular populations of M. caurina exhibited higher differentiation and lower variability relative to northern populations of M. americana. Greater divergence among M. caurina populations may reflect longer isolation and persistence in coastal forest habitat that was fragmented by rising sea level in the early Holocene. Lower differentiation among northern M. americana populations and close relationship to other continental M. americana populations may reflect more recent expansion into the Pacific Northwest and/or continued gene flow among populations. Differentiation among M. caurina populations was attributed to habitat fragmentation (i.e. rising sea level), as opposed to isolation-by-distance; oceanic straits pose significant barriers to gene flow among M. caurina populations and between populations of M. caurina and M. americana.     

Population subdivision and gene flow among wild orangutans

Genetic variability among populations of orangutans from Borneo and Sumatra was assessed using seven SSR loci. Most SSR loci were highly polymorphic and their allele frequencies exhibited substantial variation across subpopulations. While significant genetic subdivision was observed among the island populations, genetic distance did not increase with geographic distance and sufficient gene flow persists to prevent marked genetic subdivision. Since it is unlikely that the Bornean Orangutans dispersed naturally among locations separated by such formidable geographic barriers, human assistance might already have altered their genetic structure. Our data suggests that there may be at least two subspecific clades of orangutans within Borneo while Central Kalimantan animals may have become more genetically related to animals in Sumatra due to human intervention.     

Landscape-level spatial genetic structure in Quercus acutissima (Fagaceae)

Quercus acutissima (Fagaceae), a deciduous broad-leaved tree, is an important forest element in hillsides of South Korea. We used allozyme loci, Wright's F statistics, and multilocus spatial autocorrelation statistics to examine the distribution of genetic diversity within and among three local populations and the spatial genetic structure at a landscape scale (15 ha, 250 × 600 m) on Oenaro Island, South Korea. Levels of genetic diversity in Q. acutissima populations were comparable to mean values for other oak species. A moderate but significant deficit of heterozygotes (mean F(IS) = 0.069) was detected within local populations and low but significant differentiation was observed among populations (F(ST) = 0.010). Spatial autocorrelation analyses revealed little evidence of significant genetic structure at spatial scales of 100-120 m. The failure to detect genetic structure within populations may be due to intraspecific competition or random mortality among saplings, resulting in extensive thinning within maternal half-sib groups. Alternatively, low genetic differentiation at the landscape scale indicates substantial gene flow among local populations. Although wind-borne pollen may be the primary source of gene flow in Q. acutissima, these results suggest that acorn movement by animals may be more extensive than previously anticipated. Comparison of these genetic data for Oenaro Island with a disturbed isolated inland population suggests that population-to-population differences in internal genetic structure may be influenced by local variation in regeneration environment (e.g., disturbance).     

The deviation from linkage equilibrium with multiple loci varying in a stepping-stone cline

The balance between the creation of associations between alleles at different loci by immigration and the convergence to linkage equilibrium due to the recombination process is studied in a theoretical model. The geographical structure of the model is a stepping-stone chain of populations linking two genetically constant source populations. The model assumes an arbitrary number of autosomal loci and considers genetic variation (two alleles at each locus) that is not subject to natural selection. The gene frequencies at each locus will then show a linear cline through the stepping-stone chain of populations. The deviation from linkage equilibrium through the stepping-stone cline is characterized by an equation for linear measures that provide the linkage disequilibrium measures for a given set of loci in terms of the gene frequencies and the linkage disequilibria in the source populations and in terms of the linkage disequilibrium measures through the cline for lower numbers of loci. Numerical examples of this iterative solution are given, and it is shown that the build-up of the higher order Bennett-disequilibria through the cline is considerably more pronounced than the build-up of two-locus disequilibria.     

Genetic and morphological differentiation of the mangrove crab Perisesarma guttatum (Brachyura: Sesarmidae) along an East African latitudinal gradient

The genetic structure and morphometric differentiation of mangrove crab Perisesarma guttatum populations were examined among shelf connected locations along a latitudinal gradient on the East African coast. Over 2200 specimens were sampled from 23 mangrove sites for geometric morphometrics analysis. Population genetic analyses of mitochondrial cytochrome c oxidase subunit I (COI) DNA sequences were used to evaluate connectivity among populations. A total of 73 haplotypes were detected, and almost no haplotypes were found in common between two highly supported phylogeographic clades: southern Mozambique (Inhaca Island and Maputo Bay) and a northern clade that included north Mozambique, Tanzania and Kenya. These two clades were identified based on the species' populations pairwise genetic differentiation and geographical location. Φ_ST values were considerably high between the two clades, indicating the presence of significant population genetic structure between Kenya and South Mozambique. However, each clade was composed of genetically similar populations along the latitudinal gradient, and no significant population structure was found within each clade because the Φ_st values were not significant. The morphometric analysis corroborated the division into two clades (i.e. Inhaca Island/Maputo Bay and northern populations) and also detected less shape variation among populations that were few kilometres apart. The significant spatial genetic structuring between the southern and the northern populations of P. guttatum along the geographic gradient under study, combined with morphological differences, suggests that these populations may be considered as cryptic species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 28–46.     

Spatial genetic structuring in a vagile species, the European wood mouse

We examined the genetic structure of natural populations of the European wood mouse Apodemus sylvaticus at the microgeographic (<3 km) and macrogeographic (>30 km) scales. Ecological and behavioural studies indicate that this species exhibits considerable dispersal relative to its home-range size. Thus, there is potential for high gene flow over larger geographic areas. As levels of population genetic structure are related to gene flow, we hypothesized that population genetic structuring at the microgeographic level should be negligible, increasing only with geographic distance. To test this, four sites were sampled within a microgeographic scale with two additional samples at the macrogeographic level. Individuals ( n =415) were screened and analysed for seven polymorphic microsatellite loci. Contrary to our hypothesis, significant levels of population structuring were detected at both scales. Comparing genetic differentiation with geographic distance suggests increasing genetic isolation with distance. However, this distance effect was non-significant being confounded by surprisingly high levels of differentiation among microgeographic samples. We attribute this pattern of genetic differentiation to the effect of habitat fragmentation, splitting large populations into components with small effective population sizes resulting in enhanced genetic drift. Our results indicate that it is incorrect to assume genetic homogeneity among populations even where there is no evidence of physical barriers and dispersal can occur freely. In the case of A. sylvaticus , it is not clear whether dispersal does not occur across habitat barriers or behavioural dispersal occurs without consequent gene flow.     

Microsatellite analysis of North American wapiti (Cervus elaphus) populations

Eleven populations of wapiti (Cervus elaphus) were analysed for genetic diversity using 12 microsatellite loci. Samples were taken from Vancouver Island, British Columbia; Burwash and French River herds in Ontario; Ya Ha Tinda Ranch, Alberta; and Banff, Elk Island, Jasper, Kootenay, Riding Mountain, Yellowstone and Yoho National Parks. Overall, wapiti populations have on average three to four alleles per locus and an average expected heterozygosity that ranged from 25.75 to 52.85%. The greatest genetic distances were observed between the Vancouver population and all other populations. Using the assignment test, Roosevelt wapiti (C. e. roosevelti Merriam 1897) assigned only to the Vancouver Island population. The distance and assignment values suggest a divergence of the Roosevelt wapiti from other populations and support the subspecific status for the Vancouver Island population. No evidence was found for the existence of unique Eastern wapiti (C. e. canadensis Erxleben 1777) in the Burwash or French River herds in Ontario. The overlapping distribution of genotypes from indigenous populations from Riding Mountain, Elk Island and Yellowstone National Parks suggests that wapiti were once a continuous population before settlers decimated their numbers. The lack of differentiation between these populations raises questions about the status of Manitoban (C. e.manitobensis Millais 1915) and Rocky Mountain (C. e.nelsoni Bailey 1935) subspecies.