Allozyme Diversity and Geographic Variation among Populations of the Locally Endangered Taxon Carex magellanica subsp. irrigua (Cyperaceae)

Carex magellanica subsp. irrigua is a wet habitat taxon that is extinct or declining in the Baltic States and Central Europe, but still quite common in northern areas, in Fennoscandia and Alaska. We investigated the extent of genetic variation within and among populations and geographic regions of this subspecies. Isozyme electrophoresis in polyacrylamide gels was applied to characterize genetic diversity with allozymes as genetic markers. Of the nine putative isozyme loci assessed, five (56%) were found to be polymorphic. The genetic diversity in small and fragmented Estonian populations was lower (H _e?=?0.034) than in larger Fennoscandian and Alaskan populations (average H _e?=?0.082). All standard genetic parameters (A _e, H _o, H _e, P, F _is, t) showed the lowest values in Estonian populations. The heterozygosity level in Fennoscandian populations was low (H _o?=?0.01), whereas no heterozygotes were found in Estonian and Alaskan populations. High F _is values indicate that C. magellanica subsp. irrigua is predominantly inbreeding. The main reason for its decline in Estonia is the destruction of suitable habitats. More attention to the protection of Estonian habitats is needed to maintain genetic diversity and stop further decline of this taxon.     

Is the genetic diversity of small scattered forest tree populations at the southern limits of their range more prone to stochastic events? A wild cherry case study by microsatellite-based markers

Wild cherry (Prunus avium L.) is a widespread, partially asexual, noble hardwood European species characterized by a scattered distribution, small population sizes, and human exploitation for its valuable wood. These characteristics, especially at the southern limits of the species natural distribution where additional varying stresses may occur, render P. avium populations prone to potential stochastic, genetic, and demographic events. In this study, we used dominant inter simple sequence repeat (ISSR) and codominant simple sequence repeat (SSR) markers to infer the genetic structure of P. avium. Five populations from northern Greece were evaluated based on 46 ISSR and 11 SSR loci. Populations presented a relatively high level of genetic variation, with a mean genetic diversity of H _e?=?0.166 and H _e?=?0.740 regarding ISSR and SSR analysis, respectively. We observed moderate population differentiation for ISSR (G _ST?=?0.113) and SSR (F _ST?=?0.097) markers. AMOVA also detected significant differentiation among populations for ISSRs (?? _ST?=?0.338) and SRRs (?? _ST?=?0.162). According to linkage disequilibrium analysis, estimates of effective population size were generally sufficient for maintaining extant genetic variability and evolutionary potential. A possible bottleneck was detected for only one population. In general, it appears that despite the particular characteristics of the P. avium populations studied, genetic stochasticity events were not apparent. The studied populations, located at the rear edge of the species European distribution, reveal a wealth of genetic variation that is very valuable for the genetic conservation of local adaptive gene complexes, especially under contemporary climatic change scenarios.     

Genetic Structure of Oryza rufipogon Griff. Natural Populations in Malaysia: Implications for Conservation and Genetic Introgression of Cultivated Rice

Thirty polymorphic Oryza sativa microsatellite loci (SSRs) were used to study population genetic structure of O. rufipogon Griff. natural populations in Malaysia. A total of 445 alleles were detected with an average of 14.8 alleles per locus in 176 individuals of O. rufipogon sampled from the states of Penang, Kedah, Kelantan and Terengganu where the natural populations are still found. The Kelantan population in the northeast of Peninsular Malaysia had the highest level of genetic diversity as measured by the mean number of alleles per locus, A_a?=?7.67, average number of effective alleles, A_e?=?5.50, percentage of polymorphic loci, P?=?100%, observed heterozygosity, H_o?=?0.631 and expected heterozygosity, H_e?=?0.798. In contrast, the Terengganu population in the east showed the lowest level of genetic diversity measured by the same criteria (A_a?=?4.23, A_e?=?2.10, P?=?100%, H_o?=?0.549 and H_e?=?0.449). Model–based clustering analysis using the STRUCTURE 2.2 program placed all the individuals into 12 clusters that corresponded to the geographic sampling locations. Neighbour-joining tree was constructed based on Nei’s genetic distance to further assess the genetic structure of the O. rufipogon individuals, showed good agreement (93.8%) with the model-based cluster analysis. However, the neighbour-joining tree identified sub-populations that STRUCTURE could not identify. The classification of individuals from the same populations under the same cluster supported the population differentiation. These two analyses seemed to indicate expansion of populations from the northeast of Peninsular Malaysia (Tumpat, Pasir Mas and Kota Bahru, Kelantan) not only to the immediate south of the region i.e. Terengganu but also into the northwest (i.e. Penang and Kedah) with the former being more recent. Oryza rufipogon accession IRGC105491 and O. sativa ssp. indica cultivar MR219, which were included in this study for comparisons with the local wild rice accessions, indicated that introgression of cultivated rice could change genetic composition and affect the population genetic structure of wild rice. This possibility should be carefully considered in plans to conserve this wild rice.     

A morphometric analysis and taxonomic study of Panax bipinnatifidus Seem. (Araliaceae) species complex from Sikkim Himalaya, India

Cattleya elongata is a rupicolous orchid species spread throughout and endemic to outcrop islands in campo rupestre vegetation of the Chapada Diamantina, northeastern Brazil. We scored nine natural populations of C. elongata for morphological and genetic variability, covering the whole distribution area of the species, using allozymes and ISSR markers and morphometric multivariate analyses. Genetic variability in allozimes was relatively high (H _e?=?0.12?C0.25), and unexpectedly higher than the values based on ISSR (H _e?=?0.16?C0.19). The populations present moderate structuring (allozymes, ??_PT?=?0.14; ISSR, ??_PT?=?0.18) and low inbreeding (allozymes, F _IS?=?0.06). Genetic similarity among the populations was high in both markers, in spite of the discontinuity of the outcrops of the Chapada Diamantina. We found no particular biogeographical pattern to the distribution of the genetic and morphologic similarity among the populations of C. elongata. We found high morphological variability with moderate differentiation among the populations. We did not find any correlation among genetic, morphological, and geographical distances, and among the variability found in the morphological and genetic markers. The differences observed between the two genetic markers and the various morphological markers examined here indicated that the isolated use of any single parameter of these different populations for conservation planning or management would not consider all of the variability to be found in the species, as found in other Brazilian campos rupestres plants.     

Genetic Diversity Within and among Disjunct Populations of the Mediterranean Island Endemic Delphinium pictum and D. requienii (Ranunculaceae)

Allozyme diversity was assessed in 13 populations of Delphinium pictum and D. requienii, two short-lived and closely related insular Mediterranean endemics. While D. pictum has scattered distribution in Corsica, Sardinia and Majorca, D. requienii is found in a few small populations restricted to the Hyères Archipelago. Eleven enzyme systems were assayed, and 15 loci were resolved. Both species harboured moderate levels of genetic diversity, comparable to the values expected for endemic plants. All genetic parameters suggested higher diversity in D. pictum (A?=?1.93, P?=?40, H _e?=?0.106) than in D. requienii (A?=?1.30, P?=?26.7, H _e?=?0.096); F _IS values revealed higher inbreeding in D. requienii. Although the two species did not harbour species-specific alelles in the surveyed loci, the UPGMA dendrogram based on Nei’s genetic similarity index supported divergence between them. These results, together with significant morphological similarity and evidence of successful hybridization between the species, support the hypothesis of a recent speciation event. The moderate levels of both genetic variability and population divergence observed for D. pictum are likely attributable to its ability to establish seed banks. Given that the allozyme variation detected for D. pictum was significantly partitioned among islands, we suggest the implementation of conservation programs throughout its distribution range, and not only in Corsica as it occurs nowadays. Management strategies are also desirable for D. requienii to maintain population size and control inbreeding.     

Polymorphic microsatellites identified by cross-species amplifications in the European Coot Fulica atra

We tested the cross-amplification of 26 microsatellites developed for passerines and an additional three developed for Gallinula species in eight European Coots from two populations. Sixteen microsatellite markers successfully amplified, of which nine were polymorphic with 2–6 alleles (mean 3.7 alleles) and an expected heterozygosity (H _e) ranging from 0.375 to 0.805 (mean H _e = 0.589). On average, we found 2.22 alleles/locus and a mean H _e of 0.440 in one nest, and 2.56 alleles/locus and a mean H _e of 0.494 in the other one. These nine polymorphic markers could be of potential use in studies of genetic variability, population structure and reproductive strategy of European Coots.     

Gliadin polymorphism in Turkish cultivated emmer wheat [Triticum turgidum L. ssp. dicoccon (Schrank) Thell.] landraces

Gliadin polymorphism in 19 landrace populations of Turkish cultivated emmer wheat [Triticum turgidum L. ssp. dicoccon (Schrank) Thell.] was assessed using the aluminum lactic acid-polyacrylamide gel electrophoresis (A-PAGE) technique. Being a source of useful genes, landraces of wheat represent one of the most important genetic resources available to breeders for present and future genetic improvement of wheat. This is the first genetic characterization of these 19 Turkish emmer wheat landrace populations collected from their main cultivation areas. Considerably high amounts of variation were detected within and among the populations. A total of 27 alleles (n _a) were identified among all analyzed populations, 10 of them being unique to populations?C, D, H, K, L, M, and N. The highest allele number (n _a?=?7) was observed in populations?A and L, whereas the lowest number of alleles (n _a?=?3) was observed in populations?F, G, and U. The mean number of effective alleles (n _ae) was 12.33, and the mean values of gene diversity, genetic differentiation, and gene flow between populations were H _e?=?0.92, F _ST?=?0.296, and N _m ?=?0.60, respectively. Certain gliadins closely linked to dough quality, such as ??-45 and ??-35, were found in 13 and 18 of the populations, respectively. According to Pearson??s correlation coefficient values, gene diversity estimates had strong positive correlation (r _P?=?0.510; p?=?0.026 at <0.05%) with latitude. The rest of the genetic data (n _a and n _ae) obtained in the present study showed no correlation with geographic (altitude, latitude, and longitude) or climatic factors (temperature and annual rainfall). Principal component analysis was performed to explain spatial genetic variation, revealing 90.044% of total genetic variation in three components. Results obtained from this study can effectively be used in developing more efficient breeding programs to improve wheat genotypes, and to direct genetic resource conservation studies.     

Patterns of Genetic Diversity in Platanthera bifolia (Orchidaceae) with Respect to Life History Traits and Recent Range Expansion

For evolutionary and ecological analyses, genetic diversity at different scales needs to be studied in terms of biological properties, habitat, population size and population history. We surveyed Platanthera bifolia populations from six regions in northeastern Poland to determine the impact of the mating system and population history on genetic diversity. Based on variation at allozyme markers, genetic variation was relatively moderate (P?=?22.3%, A?=?1.48, H _O?=?0.083, F _IS?=??0.015) and similar to other Platanthera species. These parameters varied between populations (P?=?13.3%–26.6%, A?=?1.26–1.66, H _O?=?0.055–0.111, F _IS?=??0.262–0.147). The genetic diversity patterns were shaped by different proportions of facilitated selfing and/or outcrossing, resulting in positive and negative F _IS values, respectively. No relationship between inbreeding coefficient and population size, however, and no impact of apomixis on the level of genetic diversity of P. bifolia were found. The relatively low level of genetic differentiation among the investigated regions (F _CT?=?0.002, P?>?0.05) and among populations (F _ST?=?0.048, P?<?0.001), and the lack of a significant relationship between genetic and geographical distance, are discussed in the context of possible scenaria of postglacial expansion.     

Genetic variation and genotypic diversity in Epipactis helleborine populations from NE Poland

Enzyme electrophoreses were used to estimate genetic variation in five populations of Epipactis helleborine from two National Parks (Biebrza and Wigry) in northeast Poland. It has been proved that populations from these two regions differed in genetic structure, with the populations belonging to the Biebrza group having a higher level of genetic variation than those from Wigry. The number of polymorphic loci (P) ranged from 18.2% to 40.9% and the mean number of alleles per polymorphic locus (Ap) from 2.25 to 2.80. Although the observed heterozygosity (H_o) was lower than the expected one (H_e) in each population, the values of H_o and H_e were 2–3 times lower in the populations from Wigry than in those from Biebrza. Excluding the LUK population with the smallest genotypic diversity, the majority of 345 distinct multilocus genotypes occurred only once, sporadically 2–4 times in each population and their frequency ranged from 0.2% to 3.7%. Moreover, factors shaping genetic structure of E. helleborine and their intensity varied in the populations studied. Reproduction from seeds seems to influence greatly the genetic variation of the populations from the Biebrza National Park, while an assortative mating between related individuals or population size appears to be more important in the case of the populations from the Wigry National Park.     

Genetic variation in natural populations of Austrocedrus chilensis,a cypress of the Andean-Patagonian Forest

Austrocedrus chilensis (D. Don) Pic. Ser. et Bizzarri is a dioecious conifer of the Argentinian and Chilean Subantarctic Forest with a markedly fragmentary range. The aim of the present study is to gain information about the degree and distribution of the genetic variation of this species in natural populations of Argentina. The genotypes of 387 trees from 15 Argentinian populations were determined at 12 isozyme marker loci, half of which were virtually monomorphic. Genetic variation was characterized for the species through averaging the population values of some useful parameters. The number of alleles per locus (A=1.51) and the number of effective alleles (A_e=1.16) were small, while the expected (H_e) and the observed heterozygosities (H_o) turned out to be moderate (0.143 and 0.134, respectively). The differentiation between populations was small (δ=0.043; F_ST=0.066), with a trend towards the distribution of genetic variation along a latitudinal gradient, the northerly populations being more variable. The marginal populations from the steppe were found to be the most variable. The pattern found matches several small refuges during the Last Glacial Maximum situated eastward from the Andes mountain range in xeric environments, mostly in northern locations of the present range, followed by a considerable rate of population growth.     

Analysis of Genetic Variation in Natural Populations of Medicago truncatula of Southern Tunisian Ecological Areas, Using Morphological Traits and SSR Markers

We used 19 quantitative traits and 14 microsatellite markers (SSRs) to analyze the genetic variation in four natural populations of the model legume Medicago truncatula sampled in southern Tunisia. The greatest genetic variation of quantitative traits and molecular markers occurred within populations (>71%). In contrast to quantitative population differentiation (Q _ST ?=?0.09), a high level of molecular differentiation (F _ST ?=?0.23) was found among populations. The majority of quantitative traits exhibited Q _ST values significantly less than F _ST values, suggesting that selection may be acting to suppress differentiation for these traits. There was no significant correlation between genetic variation of quantitative traits and molecular markers within populations. On the other hand, significant correlations were found between measured quantitative characters and the site-of-origin environmental factors. The eco-geographical factors with the greatest influence on the variation of measured traits among populations were altitude, followed by soil texture, assimilated phosphorus (P₂O₅) and organic matter. Nevertheless, there were no consistent patterns of associations between gene diversity (He) and eco-geographical factors.     

High genetic diversity and significant population structure in Cedrus brevifolia Henry, a narrow endemic Mediterranean tree from Cyprus

Endemic island plant species with a narrow distribution are often, but not always, linked to low genetic variation within populations and a lack of differentiation among populations. Cedrus brevifolia is a narrow endemic island tree species of Cyprus. Its range is restricted to a single forest, divided into five neighbouring sites. This study, using biparentally inherited nuclear microsatellites and paternally inherited plastid (chloroplast) microsatellites, assessed the genetic variation of C. brevifolia within its sole population and the level of genetic differentiation among formed sites. The results from both markers showed high diversity (nuclear H _T?=?0.70; plastid H _T?=?0.93), strongly suggesting that the species did not experience severe bottleneck events or extensive genetic drift. Besides, the maintenance of a high genetic diversity in C. brevifolia may suggest that it originates from a widespread congener species. Significant genetic differentiation at nuclear (G _ST?=?0.052) and plastid (G _ST?=?0.119) markers was found among the formed sites. Remarkably, the relatively high genetic differentiation found at plastid markers was comparable to values observed in two widespread congener cedar species. The genetic differentiation probably occurred due to fragmentation of a previously uniform population. This would lead to the shaping of different genetic groups (Bayesian analysis) and to significant population substructure. Furthermore, significant values observed for both isolation by distance and large-scale spatial genetic structure could indicate ineffective gene flow among sites and the early geographical isolation of the more isolated sites from the core population.     

Genetic diversity of natural populations of Taxus mairei

Taxus mairei (Lemée & Lév.) S.Y. Hu ex T. S. Liu is a vulnerable tree species, and it is also a precious timber species in China. We used 13 microsatellites to assess the genetic diversity and differentiation of 665 T. mairei samples from 18 natural populations. A total of 291 alleles were detected. The average number of alleles (N_a?=?22.39), expected heterozygosity (H_e?=?0.74), polymorphic information content (PIC?=?0.86) and Shannon diversity index (I?=?1.66) of the loci indicated a high level of genetic diversity in natural T. mairei populations. Moreover, gene flow was more active among populations (N_m?=?1.62) than within populations. Among the 18 populations, the Xinfeng population in Jiangxi Province has the highest genetic diversity. Although each of the studied populations should be protected from further deforestation and agricultural expansion, the Xinfeng population deserves the highest conservation priority. The results based on analysis of molecular variance showed that genetic variation occurred mainly within populations (84.90%; P?<?0.001), which indicated that the degree of genetic differentiation of the natural populations of T. mairei was low. Based on UPGMA, the 18 populations were categorized into two groups. A Mantel test showed that there was no significant correlation between standard genetic distance and geographical distance or altitude differences among the populations. The genetic clustering results also indicated that there are varying degrees of gene penetration among natural populations of T. mairei. The information presented here forms the basis for the development of genetic guidelines for appropriate conservation programs.

     

Genetic structure and association mapping of adaptive and selective traits in the east Texas loblolly pine (Pinus taeda L.) breeding populations

First-generation selection (FGS) and second-generation selection (SGS) breeding populations of loblolly pine from east Texas were studied to estimate the genetic diversity, population structure, linkage disequilibrium (LD), signatures of selection and association of breeding traits with a genome-wide panel of 4,264 single nucleotide polymorphisms (SNPs). Relatively high levels of observed (H _o?=?0.178–0.198) and expected (H _e?=?0.180–0.198) heterozygosities were observed in all populations. The amount of inbreeding was very low with many populations exhibiting a slight excess of heterozygotes. The population structure was weak, but F _ST indicated more pronounced differentiation in the SGS populations. As expected for outcrossing natural populations, the genome-wide LD was low, but marker density was insufficient to deduce the decay rate. Numerous associations were found between various phenotypic traits and SNPs, but only a few remained significant after false positive correction. Signatures of diversifying and balancing selection were found in markers representing important biological functions. These results present the first step in the application of marker-assisted selection (MAS) to the Western Gulf Forest Tree Improvement Program (WGFTIP) for loblolly pine and will contribute to the knowledgebase necessary for genomic selection technology.     

Analysis of Genetic Diversity and Population Structure in Sophora japonica Linn. in China With Newly Developed SSR Markers

Sophora japonica is a medium-sized deciduous native tree to China. Its flower buds and fruits have special medicinal value. By using 26 highly variable nuclear microsatellites, newly reported here, we assessed the genetic diversity and population structure of 10 representative populations (180 individuals in total) within the species. The results revealed a relatively high genetic diversity in S. japonica (N_a?=?8.00, H_e?=?0.74, PIC?=?0.80, I?=?1.67), and reduced genetic variation and heterozygote excess were detected in landrace populations (N_a?=?5.59, H_e?=?0.71, A_r?=?4.11, F_IS?=???0.043) when compared with those semi-wild population (N_a?=?9.7, H_e?=?0.74, A_r?=?8.80, F_IS?=?0.082). A significant bottleneck was detected in two Landraces populations. Moderate differentiation and frequent gene flow were detected among all populations (F_ST?=?0.079, P?<?0.05, N_m?=?2.893). Mantel test detected a marginal significant pattern of isolation by distance (r?=?0.009, P?=?0.50), and strong differentiation was observed between most southern and northern populations both by the STRUCTURE clustering and principal coordinate analysis (PCoA), indicating that geographic isolation played a key role in the genetic differentiation of the species. The results from this study will benefit the breeding and conservation of S. japonica, other congener species, and tree species with similar life history traits.

     

Spatial Genetic Structure of Campanula sabatia, a Threatened Narrow Endemic Species of the Mediterranean Basin

Campanula sabatia is endemic to NW Italy (Liguria) and it was included in the European Red list of endangered species due to the heavy human pressure on its habitat. AFLP markers were used to detect the genetic diversity within and among ten populations (totalling 83 individuals) representing the range of the species. In spite of the limited distribution of this endemic taxon, high levels in percentage of polymorphic bands (PPB), gene diversity (H _S and H _T) and Shannon??s information index (I) were detected both at population (PPB?=?60?%, H _S?=?0.1853, I?=?0.2836) and at species level (PPB?=?100?%, H _T?=?0.2415, I?=?0.3871). The coefficient of genetic differentiation among population (G??_ST) was 0.1935, while the level of gene flow (N?? _m) was estimated to be 2.0832. AMOVA analysis identified a genetic variation within populations of 83?% of the total. Bayesian clustering methods assigned individuals to two geographical groups partly found within the same population, probably due to a high rate of genetic exchange among its populations. Conservation measures are suggested on the basis of the genetic diversity detected to ensure an effective protection for this endemic species.     

Genetic structure in peripheral Western European populations of the endangered species Cochlearia pyrenaica (Brassicaceae)

Cochlearia pyrenaica is one of the most endangered plant species in Europe, listed in many European and regional conservation policy documents (e.g. Spain, France, Belgium, Switzerland). To study its genetic structure, define its conservation units and propose a management strategy for this species, amplified fragment length polymorphism markers were used to analyse the genetic diversity within and between five representative populations of the species distribution in Western Europe (Cantabrian Range, North of Spain; Pyrenees, France; Wallonia, Belgium). Low levels of genetic diversity were revealed by the population percentage of polymorphic bands (PPB?=?36.56%), average within-population diversity (H _S?=?0.0990) and genetic diversity within populations (H _pop?=?0.1541), although high levels were reported at species level (PPB?=?81.16%; total genetic diversity for the species, H _T?=?0.0990; and genetic diversity within whole species, H _sp?=?0.2515). The coefficient of genetic differentiation among populations (G _ST) was 0.3869. The analysis of Shannon diversity index in population and for the total data set partitioned (38.72%) and AMOVA (53%) detected a high level of interpopulation diversity, in broad agreement with the result of genetic differentiation analysis. NeighborNet network and principal coordinate analyses clustered the populations in three major groups congruent with geographical regions. Bayesian clustering also confirmed these three distinct genetic clusters. The level of gene flow (Nm) was estimated as 0.3961 individuals per generation among populations, with the genetic identity (I) and genetic distance (D) among populations ranging from 0.8679 to 0.9651 and from 0.0355 to 0.1417, respectively. Therefore, the low levels of genetic variation and high divergence of regional gene pools indicate that there is a need to protect each disjunct region of Western Europe.     

Genetic variation and environmental heterogeneity in some closely related goby species

An electrophoretic study of genetic variation at 31 loci was made in nine species of gobild fish. Rank order estimates of the degree of environmental heterogeneity experienced by each of the species examined were made and correlations between genetic variation (measured as \-H_e) and this rank order were calculated. The most conservative rank correlation coefficient is 0.88 (P<0.01). The large difference in values of H_e between estuarine/shore ( H_e=0.094) and neritic/offshore ( H_e=0.044) species seems unlikely to be accounted for by differences in parameters such as population size or mutation rate. We conclude that it is probable that more variable environments are conducive to the maintenance of higher levels of genetic variation at enzyme loci in these goby populations. These results parallel findings made in numerous comparisons of laboratory populations.     

Case study of microsatellite polymorphism of European perch in selected commercially important lakes of Latvia

Polymorphism of selected microsatellite markers was described for European perch populations of inland Lake Kala and costal Lake Babites in Latvia. The data consisted of ten microsatellite loci analysed for 90 individuals from the Lake Babites (n?=?45) and the Lake Kala (n?=?45). Both lakes differ in water area, connection with the Gulf of Riga (Baltic Sea), lake type, and fish species. In the Lake Kala population, the average number of alleles per locus varied from 4 to 15 and in the population of Lake Babites from 4 to 12. Low but significant genetic differentiation was detected between populations (F_ST?=?0.046). Observed and expected heterozygosity in both lakes was similar (Kala: H_o?=?0.680 and H_e?=?0.816; Babites: H_o?=?0.693 and H_e?=?0.815). The number of unique alleles per locus was 2.3 in Lake Kala and 0.6 in Lake Babites. The present study showed relatively high polymorphism of analysed microsatellite markers.     

Genetic structure and differentiation of populations of the tetraploid species <Emphasis Type="Italic">Oxytropis chankaensis</Emphasis> (Fabaceae)

The population genetic variation of the tetraploid species Oxytropis chankaensis Jurtz. (Fabaceae), a local endemic of the western coast of Khanka Lake (Primorye), was examined. Five populations were analyzed using 28 isozyme loci encoding 16 enzyme systems. Significant allelic heterogeneity among the populations was found for six out of twelve polymorphic loci. The heterozygosity of the samples (total sample size 294 plants) H _e = 0.301 was considerable higher than the mean values in populations of endemic species (0.076). Based on the results of this study, we identified two groups of O. chankaensis populations (southern and northern), in spite of the absence of marked hiatus between them. Of special interest is the population from Przhewalski Spit, which is a natural reserve of genetic diversity of the species and the putative center of formation of the autotetraploid O. chankaensis.