Genetic variation of introduced Hawaiian and native Costa Rican populations of an invasive tropical shrub, Clidemia hirta (Melastomataceae)

Clidemia hirta is one of the most common woody invasive plants in mesic to wet forests in Hawaii, where it was introduced around 1940. The species is relatively uncommon by comparison in its native range of Central and South America and some Caribbean Islands. We examined genetic variation in allozymes of 20 C. hirta populations on four Hawaiian Islands to determine the introduction history. For comparison, we measured genetic variation in 20 native populations across Costa Rica. Mean levels of genetic variation in Hawaiian and Costa Rican populations were low compared to other woody or introduced plants (11.5-12.5% polymorphic loci, 2.05-2.50 alleles per polymorphic locus, and 0.045-0.063 expected heterozygosity). Most genetic diversity was held within rather than among populations in both areas (G(ST) = 0.120 and 0.271 in Hawaii and Costa Rica, respectively). Hawaiian populations had a high degree of genetic similarity, and no genetic differentiation was found among the four Hawaiian Islands sampled. These patterns of genetic variation in Hawaii suggest that no intraspecific hybridization of genotypes from different parts of the native range has occurred and that introductions to the different islands came from the same or similar source populations. The low levels of genetic diversity in parts of both the native and introduced ranges suggest that genetic variation is unrelated to invasiveness in C. hirta.     

Promiscuity in populations of the cushion plant Saxifraga oppositifolia in the Swiss Alps as inferred from random amplified polymorphic DNA (RAPD)

Overviews on patterns of genetic variation within and among plant populations show that widespread, outcrossing species should have a high proportion of the total genetic variation within populations and a low proportion among populations, which results in little population differentiation. However, in Alpine areas, large–scale distribution barriers as well as small-scale habitat heterogeneity could lead to geographical and temporal isolation, respectively. We investigated the genetic variation of Saxifraga oppositifolia from 10 populations of the Alps in southeastern Switzerland using random amplified polymorphic DNA (RAPD). Based on the banding patterns of four RAPD primers, 84 polymorphic markers identified all 189 sampled individuals as being genetically different. The genetic variation was mainly found within populations (95%), whereas less than 5% was found among populations and among regions. Analyses of molecular variance ( AMOVA ) suggested that population differentiation was highly significant. However, grouping populations differently into regions did not appear to result in a clear correspondence of genetic and geographical relatedness. Genetic variation did not significantly differ between populations of two elevational levels. This coincides with results of former pollination experiments that revealed a breeding system of S. oppositifolia which remains the same irrespective of the elevation. We assume that the high outcrossing rate, rare clonal reproduction, and some long-distance dispersal even among topographically separated populations are the crucial determinants for the pattern of genetic variation found in the investigated area.     

Conservation genetics of the endangered endemic Hawaiian genus Brighamia (Campanulaceae)

The endemic Hawaiian genus Brighamia (Campanulaceae) comprises two federally endangered, morphologically similar species, B. insignis from Kaua`i and Ni`ihau and B. rockii from Moloka`i. To assist the design of conservation management programs for these taxa, isozyme analyses were performed to assess the levels of genetic diversity at the population and species levels, including comparisons within and among seven natural populations and one ex situ collection each of B. insignis and B. rockii. Our sampling (N = 80) represents ~41% of all known individuals in the wild. Isozyme analyses revealed levels of genetic variation comparable to those reported for other Hawaiian flowering plant taxa but low levels of genetic variation at the population and species levels when compared to flowering plants in general. Ex situ individuals (N = 61) were genetically representative of natural populations and hence may appropriately serve as stock for population augmentations. The two morphologically similar Brighamia species were highly distinct genetically. The combination of morphological and ecological similarity with allozymic dissimilarity observed in Brighamia is unique among the Hawaiian taxa studied to date.     

Reconciling actual and inferred population histories in the house finch (Carpodacus mexicanus) by AFLP analysis

The house finch (Carpodacus mexicanus) is a native songbird of western North America that was introduced to the eastern United States and Hawaiian Islands in historic times. As such, it provides an unusually good opportunity to test the ability of molecular markers to recover recent details of a known population history. To investigate this prospect, genetic variation in 172 individuals from 16 populations in the western and eastern United States, southeastern Canada, Hawaiian Islands, and Mexico, as well as genetic variation in the closely related purple finch (Carpodacus purpureus) and Cassin's finch (Carpodacus cassinii) was studied by a semi-automated fluorescence-labeled amplified fragment length polymorphism (AFLP) marker system. A total of 363 markers were generated, of which 258 (71.2%) were polymorphic among species, 166 (61.4%) polymorphic among house finch subspecies, and 157 (60.2%) polymorphic among populations within the frontalis subspecies complex. Heterozygosities and interpopulation divergences revealed by the analysis appeared relatively low at all taxonomic levels, but there are few similar studies in avian populations with which to compare results. Whereas the known population history predicts that both eastern and Hawaiian finches should have been derived from within western populations, tree analysis using both populations and individuals as units suggests weak monophyly of eastern populations and indicates that Hawaiian populations are not clearly derived from California populations. However, the genetic distinctiveness of native and recently founded populations was disclosed by analyses of molecular variance as well as by a model-based assignment approach in which 98%, 94%, and 99% individuals from western, Hawaiian, and eastern regions, respectively, were assigned correctly to their populations without using prior information on population of origin, suggesting that these recent introductions have resulted in detectable differentiation without substantial loss of AFLP diversity. Our results indicate that AFLPs are a useful tool for population genetic and evolutionary studies of birds, particularly as a prelude to finding molecular markers linked to traits subjected to recent adaptive evolution.     

Molecular analysis of the Pleistocene history of Saxifraga oppositifolia in the Alps

A recent circumpolar survey of chloroplast DNA (cpDNA) haplotypes identified Pleistocene glacial refugia for the Arctic-Alpine Saxifraga oppositifolia in the Arctic and, potentially, at more southern latitudes. However, evidence for glacial refugia within the ice sheet covering northern Europe during the last glacial period was not detected either with cpDNA or in another study of S. oppositifolia that surveyed random amplified polymorphic DNA (RAPD) variation. If any genotypes survived in such refugia, they must have been swamped by massive postglacial immigration of periglacial genotypes. The present study tested whether it is possible to reconstruct the Pleistocene history of S. oppositifolia in the European Alps using molecular methods. Restriction fragment length polymorphism (RFLP) analysis of cpDNA of S. oppositifolia, partly sampled from potential nunatak areas, detected two common European haplotypes throughout the Alps, while three populations harboured two additional, rare haplotypes. RAPD analysis confirmed the results of former studies on S. oppositifolia; high within, but low among population genetic variation and no particular geographical patterning. Some Alpine populations were not perfectly nested in this common gene pool and contained private RAPD markers, high molecular variance or rare cpDNA haplotypes, indicating that the species could possibly have survived on ice-free mountain tops (nunataks) in some parts of the Alps during the last glaciation. However, the overall lack of a geographical genetic pattern suggests that there was massive immigration of cpDNA and RAPD genotypes by seed and pollen flow during postglacial times. Thus, the glacial history of S. oppositifolia in the Alps appears to resemble closely that suggested previously for the species in northern Europe.     

Patterns of genetic variation in rare and widespread plant congeners

Rare species are typically considered to maintain low levels of genetic variation, and this view has been supported by several reviews of large numbers of isozyme studies. Although these reviews have provided valuable data on levels of variability in plant species in general, and rare species in particular, these broad overviews involve comparisons that may confound the effects of rarity with a multitude of other factors that affect genetic variability. Additionally, the statistical analyses employed assume the data to be independent, which is not the case for organisms that share a common phylogenetic history. As the role of evolutionary history and historical constraints has become better understood, more researchers have studied widespread congeners when investigating the genetic diversity of rare species in an effort to control for these effects. We summarize the available data from such studies, comparing for rare and widespread congeners (1) the levels of genetic variability at the population and species levels and (2) measures of population substructuring. At the population level, we summarized data for percentage polymorphic loci (%P(pop)), mean number of alleles per locus (A(pop)), and observed heterozygosity (H(o)). Species-level measures used were percentage polymorphic loci (%P(spp)), mean number of alleles per locus (A(spp)), and total genetic diversity (H(T)). Indices of population subdivision (either F(ST) or G(ST)) were also examined. Using Wilcoxon signed rank tests, we found significant, but small, differences between rare and widespread species for all diversity measures except H(T). However, there does not appear to be a difference between rare and widespread congeners in terms of how genetic variation is partitioned within and among populations. Levels of diversity, for all measures examined, between rare and widespread congeners are highly correlated.     

Conservation Genetics of Jacquemontia reclinata (Convolvulaceae), an Endangered Species from Southern Florida: Implications for Restoration Management

Guidelines designed to aid in the restoration of rare species have been previously proposed using two primary strategies to select individuals for augmentation and reintroduction: mixing progeny from different populations or separating individuals from different populations. Understanding the genetic structure and diversity of an endangered species can offer insights into conservation management strategies. We used random amplified polymorphic DNA markers to assess the genetic structure and diversity of Jacquemontia reclinata , a federally endangered species endemic to Southeastern Florida. We sampled 20 percent of total number of individuals from eight of the ten known wild populations. Across individuals high levels of polymorphic loci (94.7%) were found and larger populations had greater genetic diversity. Cluster and ordination analyses found that one population was genetically differentiated from all the others; this population grows in a unique habitat. Most genetic variation (77.5%) was found within populations, and genetic distances between populations were not explained by their geographic distances. We recommend the use of two management units in restoration programs for J. reclinata , one consisting of the genetically differentiated population and the second consisting of the other seven populations sampled.     

Genetic diversity and morphological differentiation in Liatris helleri (Asteraceae), a threatened plant species

Liatris helleri (Asteraceae) is an insect-pollinated herbaceous perennial endemic to several high-elevation sites in the Blue Ridge Mountains of North Carolina. Allozymes were used to describe the genetic diversity and population structure in nine populations of this rare, federally listed species. Differences in leaf morphology were also examined for greenhouse-grown plants representing several populations. The proportion of the total genetic diversity found among populations, as indicated by the allozyme data, was 16%. Higher levels of population differentiation were found for differences in leaf shape; population of origin accounted for 37% of the variation in maximum leaf width, while families within populations accounted for 7%. In contrast to many endemic species, L. helleri maintains fairly high levels of genetic diversity. For the species, the percent polymorphic loci was 87.5, the average number of alleles at variable loci was 3.00 and the gene diversity was 0.276. Mean population values were percent polymorphic loci =58.4, mean number of alleles per polymorphic locus =2.59 and gene diversity =0.219. The estimated gene flow was low (Nm=0.85–1.32) and a relatively high correlation (r=0.55; p<0.005) was found between linear geographic and genetic distance. This suggests that the populations are partially isolated by distance, despite the limited range (<60 km) of the species. We recommend that population distinetiveness be maintained in restoration efforts.     

A geographic mosaic of passive dispersal: population structure in the endemic Hawaiian amber snail Succinea caduca (Mighels, 1845)

We used 276 cytochrome c oxidase subunit I (COI, 645 bp) and a subset of 84 16S large ribosomal subunit (16S, 451 bp) sequences to evaluate geographic patterns of genetic variation in 24 populations of the endemic Hawaiian land snail Succinea caduca spanning its range on six islands. Haplotype networks, gene tree topologies, pairwise molecular divergence and F _ST matrices suggest substantial geographic genetic structuring and complex dispersal patterns. Low nucleotide diversity and low pairwise molecular divergence values within populations coupled with higher between population values suggest multiple founder events. High overall haplotype diversity suggests diversification involving rare interpopulation dispersal, fragmentation by historical lava flows and variation in habitat structure. Within-island rather than between-island population comparisons accounted for the majority of molecular variance. Although 98% of 153 COI haplotypes were private by population, a Mantel test showed no evidence for isolation by distance. Mismatch distributions and population partitioning patterns suggest that genetic fragmentation has been driven by punctuated, passive dispersal of groups of closely related haplotypes that subsequently expanded and persisted in isolation for long periods (average > 2 million years ago), and that Pleistocene island connections may have been important in enhancing gene flow. Historical availability of mesic coastal habitat, together with effective dispersal may explain the long-term persistence and unusual multi-island distribution of this species, contrasting with the single-island endemism of much of the Hawaiian biota.     

GENETIC DIVERSITY AND POPULATION STRUCTURE IN TRADESCANTIA HIRSUTICAULIS (COMMELINACEAE)

Tradescantia hirsuticaulis, the hairy-stemmed spiderwort, is an insect-pollinated perennial plant species found primarily on rock outcrops in Georgia, South Carolina, and Alabama. Although populations of T. hirsuticaulis are rare and scattered, local populations are frequently large. Levels of genetic variation were assessed for 13 populations representing the species' range in these three states. Despite the disjunct distribution of this habitat specialist and apparent lack of specialized seed and pollen dispersal mechanisms, exceptionally high levels of genetic variation are maintained within the species, with a moderate level of variation (18%) found among populations. Twenty-nine of the 33 loci resolved (88%) were polymorphic within the species; the mean number of loci polymorphic within populations was 54%. The mean number of alleles per polymorphic locus was 3.24 across all populations and averaged 2.37 within populations. Genetic diversity was 0.206 for the species, whereas mean population genetic diversity was 0.157, both much higher than the average for other short-lived herbaceous perennials. Estimated levels of gene flow were moderate (Nm = 0.95), and a significant association between geographic distance and genetic distance between populations was found (r = 0.68; P < 0.0001). Habitat destruction is the major threat to this genetically diverse species. Since gene flow among its highly dispersed populations is limited, diminution or extinction of local populations could jeopardize the long-term evolutionary potential of this species.     

Genetic Diversity in Cymophyllus fraserianus (Cyperaceae), a Rare Monotypic Genus

Cymophyllus fraserianus (Fraser's sedge) is a rare perennial evergreen herb found in late-successional forest communities in the Appalachian Mountains of the U.S. Genetic diversity was assessed at 19 allozyme loci for 12 populations sampled from the southern and central portions of the range of this primitive monotypic genus. Species variation was comparable to that found for other narrowly distributed species, although mean population genetic diversity was somewhat higher. Sixteen of the 19 loci (84%) were polymorphic, with a mean of 46% polymorphic within populations. On average, 2.7 alleles were detected per polymorphic locus. Genetic diversity within populations (Hep) averaged 0.113, whereas species' genetic diversity (Hes) was 0.131. Although a twofold range of within-population genetic diversity (Hep = 0.075-0.158) was found, less than 13% of the genetic variation was distributed among populations (G(ST) = 0.129). An indirect estimate of historical levels of gene flow (Nm = 1.69) was consistent with the high mean genetic identity (mean I = 0.96) found between populations. Despite the relictual nature of C. fraserianus, its rarity and fragmented distribution, genetic diversity within the genus is typical of herbs with similar life-history characteristics. No association was found between geographic and genetic distances between populations (r = -0.01; p > 0.9), suggesting that present day populations are relatively isolated.     

华中特有珍稀植物裸芸香的AFLP遗传多样性分析

采用选择性扩增片段多态性(AFLP)方法对华中特有单种属植物裸芸香(Psilopeganum sinense)的8个自然居群的遗传多样性进行了检测与分析。结果表明:裸芸香的遗传多样性较低,且居群内遗传多样性显著低于物种水平遗传多样性。筛选出的5对引物共得到180个位点,76个为多态位点,多态位点百分率为42.2%,8个居群多态位点百分率为:3.3%～16.7%,居群平均多态位点百分率为9.4%;8个居群Nei多样性指数为0.01987～0.06987,Shannon’s多样性指数为0.0197～0.0816。居群间分化系数Gst=0.5069,居群间基因流为0.2432,不足以维持居群间的基因交流及现有的遗传结构。AMOVA分析表明总遗传变异的13.17%存在于4个地理区域之间,50.45%存在于地理区域内的居群间,36.38%的遗传变异存在于居群内个体间。NTSYS分析表明遗传距离与地理距离不存在相关关系。UPGMA聚类结果表明长江南北两岸的居群并没有产生明显分化。最后,分析了裸芸香的濒危原因并提出了有效的保育措施。     

Genetic diversity and gene flow in the morphologically variable, rare endemics Begonia dregei and Begonia homonyma (Begoniaceae)

Begonia dregei and B. homonyma (Begoniaceae), rare plants endemic to coastal forests of eastern South Africa, are two closely related species with high levels of variation among populations in the shape of leaves. Distribution of genetic variation and genetic relatedness were investigated in 12 populations of B. dregei and seven of B. homonyma using polyacrylamide gel electrophoresis. Twelve of the 15 enzyme loci examined were polymorphic, but only seven loci were polymorphic within at least one population. Genetic diversity measures indicated that the among-population gene differentiation represents >90% of the total genetic component in both species considered individually or combined. This indicated restricted gene flow, consistent with the limited dispersal abilities of Begonia generally and the ancient separation of isolated forest patches. Genetic distances among populations are much higher than usually found within species. Allozyme data provide no support for the recognition of B. dregei and B. homonyma as distinct species.     

Molecular markers reveal little genetic differentiation among Aconitum noveboracense and A. columbianum (Ranunculaceae) populations

Aconitum noveboracense, a rare, herbaceous perennial, is restricted to recently unglaciated areas in Iowa, Wisconsin, Ohio, and New York, and federally classified as a threatened species. These populations may be disjuncts of the common congener, A. columbianum Nutt., which occurs in the mountains of the western United States. Morphological characters do not reliably separate these taxa. The identity of Black Hills populations, located between the ranges of the rare and common species, is also uncertain. We characterized genetic variation within and among the Aconitum populations in question using isozymes and randomly amplified polymorphic DNA (RAPDs). Isozymes indicate a high degree of similarity among all populations and a high level of genetic diversity in Black Hills populations. Of 97 scorable RAPD loci, 89.7% are polymorphic and clearly resolve most populations. Like isozymes, RAPDs indicate high levels of genetic diversity in the Black Hills and very strong similarity of these populations to A. columbianum from the Bighorn Mountains. Aconitum noveboracense populations show >80% similarity to A. columbianum populations. A population of A. uncinatum from Ohio shows the greatest differentiation from other populations. Therefore, both isozyme and RAPD data concur with the recent treatment of A. noveboracense and A. columbianum as a single species.     

Evidence of population bottleneck in Astragalus michauxii (Fabaceae), a narrow endemic of the southeastern United States

Genetic factors such as decreased genetic diversity and increased homozygosity can have detrimental effects on rare species, and may ultimately limit potential adaptation and exacerbate population declines. The Gulf and Atlantic Coastal Plain physiographic region has the second highest level of endemism in the continental USA, but habitat fragmentation and land use changes have resulted in catastrophic population declines for many species. Astragalus michauxii (Fabaceae) is an herbaceous plant endemic to the region that is considered vulnerable to extinction, with populations generally consisting of fewer than 20 individuals. We developed eight polymorphic microsatellites and genotyped 355 individuals from 24 populations. We characterized the population genetic diversity and structure, tested for evidence of past bottlenecks, and identified evidence of contemporary gene flow between populations. The mean ratios of the number of alleles to the allelic range (M ratio) across loci for A. michauxii populations were well below the threshold of 0.68 identified as indicative of a past genetic bottleneck. Genetic diversity estimates were similar across regions and populations, and comparable to other long-lived perennial species. Within-population genetic variation accounted for 92 % of the total genetic variation found in the species. Finally, there is evidence for contemporary gene flow among the populations in North Carolina. Although genetic factors can threaten rare species, maintaining habitats through prescribed burning, in concert with other interventions such as population augmentation or (re)introduction, are likely most critical to the long term survival of A. michauxii.     

Genetic implications of bottleneck effects of differing severities on genetic diversity in naturally recovering populations: An example from Hawaiian coot and Hawaiian gallinule

The evolutionary trajectory of populations through time is influenced by the interplay of forces (biological, evolutionary, and anthropogenic) acting on the standing genetic variation. We used microsatellite and mitochondrial loci to examine the influence of population declines, of varying severity, on genetic diversity within two Hawaiian endemic waterbirds, the Hawaiian coot and Hawaiian gallinule, by comparing historical (samples collected in the late 1800s and early 1900s) and modern (collected in 2012–2013) populations. Population declines simultaneously experienced by Hawaiian coots and Hawaiian gallinules differentially shaped the evolutionary trajectory of these two populations. Within Hawaiian coot, large reductions (between −38.4% and −51.4%) in mitochondrial diversity were observed, although minimal differences were observed in the distribution of allelic and haplotypic frequencies between sampled time periods. Conversely, for Hawaiian gallinule, allelic frequencies were strongly differentiated between time periods, signatures of a genetic bottleneck were detected, and biases in means of the effective population size were observed at microsatellite loci. The strength of the decline appears to have had a greater influence on genetic diversity within Hawaiian gallinule than Hawaiian coot, coincident with the reduction in census size. These species exhibit similar life history characteristics and generation times; therefore, we hypothesize that differences in behavior and colonization history are likely playing a large role in how allelic and haplotypic frequencies are being shaped through time. Furthermore, differences in patterns of genetic diversity within Hawaiian coot and Hawaiian gallinule highlight the influence of demographic and evolutionary processes in shaping how species respond genetically to ecological stressors.     

Isolation and characterization of microsatellite loci from Corydalis ambigua (Papaveraceae)

Primers for seven unlinked and highly polymorphic microsatellite loci were developed for Corydalis ambigua to investigate its mating system and population genetics. This species can be used to explore the impact of an alien bumblebee on plant reproduction. Genetic diversity and other population genetic parameters were estimated in two populations with and without the alien bumblebee. The number of alleles per locus ranged from 4 to 20, and observed heterozygosities ranged from 0.355 to 0.969. These markers can be applied to study mating systems and population genetics in C. ambigua.     

High genetic diversity in a remote island population system: sans sex

It has been proposed that long-distance dispersal of mosses to the Hawaiian Islands rarely occurs and that the Hawaiian population of the allopolyploid peat moss Sphagnum palustre probably resulted from a single dispersal event. Here, we used microsatellites to investigate whether the Hawaiian population of the dioicous S. palustre had a single founder and to compare its genetic diversity to that found in populations of S. palustre in other regions. The genetic diversity of the Hawaiian population is comparable to that of larger population systems. Several lines of evidence, including a lack of sporophytes and an apparently restricted natural distribution, suggest that sexual reproduction is absent in the Hawaiian plants. In addition, all samples of Hawaiian S. palustre share a genetic trait rare in other populations. Time to most recent ancestor (TMRCA) analysis indicates that the Hawaiian population was probably founded 49-51 kyr ago. It appears that all Hawaiian plants of S. palustre descend from a single founder via vegetative propagation. The long-term viability of this clonal population coupled with the development of significant genetic diversity suggests that vegetative propagation in a moss does not necessarily preclude evolutionary success in the long term.     

Genetic diversity and multilocus genetic structure in the relictual endemic herb<Emphasis Type="Italic"> Japonolirion osense</Emphasis> (Petrosaviaceae)

Plant clonality may greatly reduce effective population size and influence management strategies of rare and endangered species. We examined genetic diversity and the extent of clonality in four populations of the monotypic herbaceous perennial Japonolirion osense, which is one of the most rare flowering plants in Japan. Allozyme analysis revealed moderate levels of genetic variation, and the proportion of polymorphic loci (P=66.7%) was higher than the value for species with similar life-history traits. With four polymorphic loci, 19 multilocus genotypes were observed among 433 aerial shoot samples and 10 (52%) were found only in single populations. The proportion of distinguishable genotypes (PD=0.10) and Simpson's index of diversity (D=0.52) also exhibited moderate levels of genotypic diversity compared to other clonal plants, with genotype frequencies at Hardy-Weinberg equilibrium. The distributions of genotypes were often localized and they were mostly found within a radius of 5 m. Spatial autocorrelation analysis showed that shoot samples located 4 m apart were expected to be genetically independent. The results suggest that the spatial extent of genets was relatively narrow and thus the clonality was not extensive.     

准噶尔无叶豆片断化居群的遗传变异及克隆多样性

准噶尔无叶豆(Eremosparton songoricum)是豆科无叶豆属小半灌木, 既能开花结实进行有性繁殖, 又可以靠根茎进行无性克隆繁殖, 为国家三级保护植物, 在中国仅片断化分布于新疆古尔班通古特沙漠局部区域。本文采用ISSR分子标记对采自古尔班通古特沙漠腹地及边缘的7个准噶尔无叶豆自然居群共148个个体进行了遗传变异和克隆多样性分析。8个引物共扩增出84个位点, 其中77个为多态性位点, 物种水平上的多态位点百分比PPB为91.67％, Nei's基因多样性指数I为0.3192, Shannon信息指数H为0.3540; 居群水平上的多态位点百分比PPB为58.45％, Nei's基因多样性指数I为0.2248, Shannon信息指数H为0.3270。居群间的遗传分化系数G_ST为0.2978。AMOVA分析表明, 有31.88%的遗传变异存在于居群间, 表明居群间存在显著的遗传分化。克隆多样性分析表明, 居群水平上, 居群G的Simpson多样性指数和均匀度指数最高, 分别为0.9400和0.9885; 居群E最低, 分别为0.8457和0.9021。物种水平上, Simpson多样性指数为0.9858, 均匀度指数为0.9673。本研究结果表明, 和其他荒漠植物相比, 准噶尔无叶豆表现出较高的遗传变异水平和克隆多样性, 这主要与该物种兼性生殖的繁育方式及多克隆起源有关; 而居群间产生了显著的遗传分化则主要由于人为干扰引起的生境片断化和居群减小而导致的基因交流障碍所致。遗传变异水平和遗传结构的研究将为分析准噶尔无叶豆致濒原因及进化潜力提供重要资料, 对该物种保护具有指导意义。