Implications of contrasting patterns of genetic variability in two vespertilionid bats from the Indonesian archipelago

Wallacean island populations of two Vespertilioninae bats, Myotis muricola and Scotophilus kuhlii , which have similar geographical ranges, showed marked contrast in the amount and pattern of genetic variation. Within islands, genetic variation was on average much higher in M. muricola but declined from west to east, whereas all populations of S. kuhlii had uniformly low levels of genetic variation by mammalian standards. S. kuhlii showed little genetic differentiation between islands and estimates of gene flow were substantial whereas island populations of M. muricola differed markedly and there was a strong isolation-by-distance effect associated with the extent of the sea crossing between islands. Furthermore, the lower mean heterozygosity and small genetic distances between eastern island populations of M. muricola is evidence that there has been a bottleneck associated with the colonization of this area. The attenuation of genetic diversity to the east is also seen in some other mammalian species and may indicate limits to dispersal and have implications for species management. The patterns of variability in S. kuhlii may be a consequence of its strong dispersal capacity and close association with human activity, which, together with other factors, suggest a panmictic population.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 421–431.     

Carnivores, biases and Bergmann's rule

Studies of Bergmann's rule may encompass a non-random subsample of extant homeotherms. We examined patterns of correlation between skull length and geographical latitude in 44 species of carnivores in order to test the validity of Bergmann's rule in the Carnivora. Results were then compared to those of other studies. Significant positive correlation between skull length and latitude was found in 50% of carnivore species, while significant negative correlation was found in only 11% of species. These results indicate that the occurrence of Bergmann's rule in the Carnivora is less frequent than earlier published data suggest. Publication bias is not detected in published data. Therefore, previous studies of geographical size variation might be biased in favour of species known to follow Bergmann's rule.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 579–588.     

The genetic structure of the steppe plant Iris aphylla L. at the northern limit of its geographical range

Genetic diversity of Iris aphylla was examined in seven Polish populations located at the northern limit of the geographical range of the species. Using RAPD analysis, 491 DNA fragments were amplified, all of which were polymorphic. The peripheral populations were characterized by a low number of unique bands (one to three per population) and moderate values of genetic diversity parameters (percent of polymorphic loci = 30.6%, Shannon's index = 0.149 and Nei's gene diversity = 0.097, on average), which can be explained as being due to the recent expansion of the European biota and the extremely low frequency or absence of seed set and of juveniles, as well as limited pollen and seed dispersal. There was also no significant correlation between ecological properties (population size; number of flowering ramets and fruits) and genetic diversity parameters. Despite this fact, more fixed loci were noted in the smallest populations than were in the largest ones. All populations were significantly differentiated and geographically structured. Analysis of molecular variance between regions showed a low and nonsignificant value, but relatively high molecular variation was partitioned among and within populations. Only one group of south-eastern populations was structured according to isolation by distance pattern and neighbour-joining cluster analysis. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 152 , 245–255.     

Stability of genetic structure and effective population size inferred from temporal changes of microsatellite DNA polymorphisms in the land snail Helix aspersa (Gastropoda: Helicidae)

Temporal evolution of genetic variability may have far-reaching consequences for a diverse array of evolutionary processes. Within the polders of the Bay of Mont-Saint-Michel (France), populations of the land snail Helix aspersa are characterized by a metapopulation structure with occasional extinction processes resulting from farming practices. A temporal survey of genetic structure in H . aspersa was carried out using variability at four microsatellite loci, in ten populations sampled two years apart. Levels of within-population genetic variation, as measured by allelic richness, H _e or F _is , did not change over time and similar levels of population differentiation were demonstrated for both sampling years. The extent of genetic differentiation between temporal samples of the same population established (i) a stable structure for six populations, and (ii) substantial genetic changes for four populations. Using classical F -statistics and a maximum likelihood method, estimates of the effective population size ( N _e) illustrated a mixture of stable populations with high N _e, and unstable populations characterized by very small N _e estimates (of 5–11 individuals). Owing to human disturbances, intermittent gene flow and genetic drift are likely to be the predominant evolutionary processes shaping the observed genetic structure. However, the practice of multiple matings and sperm storage is likely to provide a reservoir of variability, minimizing the eroding genetic effects of population size reduction and increasing the effective population size.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 89–102.     

Population genetics of Dioon edule Lindl. (Zamiaceae, Cycadales): biogeographical and evolutionary implications

Dioon edule Lindl. (Zamiaceae) is a cycad endemic to Mexico, that occurs as one species D. edule and the geographical variety D. edule var. angustifolium (Miq.) Miq. Dioon edule has a north to south distribution in eastern Mexico. In this study, we analysed 14 allozymic loci in eight populations of D. edule from its total distribution range by sampling all known populations. Patterns of diversity and genetic variability, within and among populations, were obtained. The mean number of alleles per locus ( A ) was 1.44 and the percentage of polymorphic loci was relatively high ( P  = 54.78). The mean observed ( H _O ) and expected heterozygosity ( H _E ) were 0.27 and 0.24, respectively. F -statistics revealed an excess of heterozygous genotypes, locally and globally ( F  = −0.17 and f  = −0.27, respectively). The genetic variation explained by differences among populations was only 7.5%. We also detected a negative relationship between genetic diversity and latitude. On average, the gene flow between population pairs was relatively high ( Nm  = 2.98); furthermore, gene flow between population pairs was significantly correlated with geographical distances ( r  = −0.38, P  = 0.025). Therefore, patterns of genetic diversity in D. edule appear to be associated with the post-Pleistocene spread of the species, from its southerly (origin) to its northerly range (derived populations, including its central distribution). The biogeographical and evolutionary aspects of the results of this study are discussed. We recognize Dioon angustifolium Miq. for the northernmost disjunct populations.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 457–467     

Variation in body size and sexual dimorphism across geographical and environmental space in the frogs Limnodynastes tasmaniensis and L. peronii

This study aimed to identify potential factors responsible for geographically structured morphological variation within the widespread Australian frogs Limnodynastes tasmaniensis Günther and L. peronii Duméril & Bibron. There was support for James's rule, and both latitude and present climate explained large amounts of the variation in body size and shape (particularly in L. peronii ). There was also some support for the influence of several biogeographical barriers. Finally, both species were sexually dimorphic for body size and the degree of sexual size dimorphism (SSD) varied geographically. Climate was an important explanation for SSD variation in L. peronii , while latitude was most important for L. tasmaniensis . Geographical variations in sexual selection via male–male physical competition and climate-related resources are suggested as potential explanations for SSD variation in L. peronii .  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 39–56.     

Population genetic structure of New Zealand's endemic corophiid amphipods: evidence for allopatric speciation

Allozyme electrophoresis was used to examine population genetic structure at inter- and intraspecific levels for the New Zealand endemic corophiid amphipods, Paracorophium lucasi and P. excavatum. Individuals were collected from estuarine and freshwater habitats from North, South and Chatham Islands. Analyses of genetic structure among interspecific populations indicated clear allelic differentiation between the two Paracorophium species (Nei's genetic distance, D  = 1.62), as well as considerable intraspecific substructuring ( D  = 0.15–0.65). These levels of divergence are similar to interspecific levels for other amphipods and it is proposed that at least two groups from the P. lucasi complex and three from the P. excavatum complex correspond to sibling species. In most cases allopatry can account for the differentiation among the putative sibling species. For populations that share a common coastline we found low levels of differentiation and little or no correlation with geographical distance, suggesting that gene flow is adequate to maintain homogeneous population genetic structure. By contrast, populations on separate coastlines (i.e. isolated by land) showed moderate levels of geographical differentiation indicating restricted gene flow. The juxtaposition of population genetic and biogeographical data for Paracorophium in conjunction with the geological record infers past histories of glacial extirpation, and possible isolating effects of sea-level and landmass changes that have occurred throughout the Plio-Pleistocene.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 119–133.     

Allozyme diversity and history of distribution expansion in the maritime perennial plant Hedyotis strigulosa (Rubiaceae), distributed over the wide latitudes in the Japanese Archipelago

Allozyme diversity was examined in 30 populations of the maritime perennial plant Hedyotis strigulosa var. parviflora , which is distributed from subtropical islands to the central mainland of Japan. Genetic diversity within populations tended to be larger in southern island populations than in northern mainland populations. In the southern part of the distribution, the population size is generally large and populations are distributed more continuously than in the northern area, resulting in the larger effective size of southern populations as a whole. These factors play a major role in maintaining greater genetic diversity in the southern populations. By contrast, genetic diversity in the northern populations is very low, probably resulting from bottlenecks of population establishments during recolonization from refugial area to the northern areas. Geographically close populations were located near each other in the multidimensional scaling and the phenogram based on genetic distances, suggesting that gene flow among remote populations is rather limited. The pattern of genetic diversity in H. strigulosa var. parviflora is likely caused by the distribution expansion of the species; in the last glacier era, the species was restricted to the southern area; its advance to the northern area is relatively recent. Another variety endemic only to the Daito Islands, H. strigulos a var. luxurians , has lower genetic diversity than H. strigulosa var. parviflora and has genetically diverged from H. strigulosa var. parviflor a.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 679–688.     

Microsatellite DNA analysis of northern pike (Esox lucius L.) populations: insights into the genetic structure and demographic history of a genetically depauperate species

The northern pike Esox lucius L. is a freshwater fish exhibiting pronounced population subdivision and low genetic variability. However, there is limited knowledge on phylogeographical patterns within the species, and it is not known whether the low genetic variability reflects primarily current low effective population sizes or historical bottlenecks. We analysed six microsatellite loci in ten populations from Europe and North America. Genetic variation was low, with the average number of alleles within populations ranging from 2.3 to 4.0 per locus. Genetic differentiation among populations was high (overall θ_ST = 0.51; overall ρ_ST = 0.50). Multidimensional scaling analysis of genetic distances between populations and spatial analysis of molecular variance suggested a single phylogeographical race within the sampled populations from northern Europe, whereas North American and southern European populations were highly distinct. A population from Ireland was monomorphic at all loci, presumably reflecting founder events associated with introduction of the species to the island in the sixteenth century. Bayesian analysis of demographic parameters showed differences in θ (a product of effective population size and mutation rate) among populations from large and small water bodies, but the relative differences in θ were smaller than expected, which could reflect population subdivision within the larger water bodies. Finally, the analyses showed drastic population declines on a time scale of several thousand years within European populations, which we ascribe to either glacial bottlenecks or postglacial founder events.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 91–101.     

Genetic variation and structure in native populations of the fire ant Solenopsis invicta: evolutionary and demographic implications

We studied population genetic variation and structure in the fire ant Solenopsis invicta using nuclear genotypic and mitochondrial DNA (mtDNA) sequence data obtained from samples collected throughout its native range. Geographic populations are strongly differentiated at both genomes, with such structure more pronounced in Brazil than in Argentina. Higher-level regional structure is evident from the occurrence of isolation-by-distance patterns among populations, the recognition of clusters of genetically similar, geographically adjacent populations by ordination analysis, and the detection of an mtDNA discontinuity between Argentina and Brazil coinciding with a previously identified landform of biogeographical relevance. Multiple lines of evidence from both genomes suggest that the ancestors of the ants we studied resembled extant northern Argentine S. invicta , and that existing Brazilian populations were established more recently by serial long-distance colonizations and/or range expansions. The most compelling evidence for this is the corresponding increase in F _K (a measure of divergence from a hypothetical ancestor) and decrease in genetic diversity with distance from the Corrientes population in northern Argentina. Relatively deep sequence divergence among several mtDNA clades, coupled with geographical partitioning of many of them, suggests prolonged occupation of South America by S. invicta in more-or-less isolated regional populations. Such populations appear, in some cases, to have come into secondary contact without regaining the capacity to freely interbreed. We conclude that nominal S. invicta in its native range comprises multiple entities that are sufficiently genetically isolated and diverged to have embarked on independent evolutionary paths.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 541–560.     

Phylogeography of the pool frog (Rana lessonae Camerano) in Europe: evidence for native status in Great Britain and for an unusual postglacial colonization route

The pool frog, Rana lessonae , has historically been considered an introduction into Britain, with Italy the most likely source. Recently, the possibility of native status for a Norfolk pool frog population was raised. We used random amplified DNA (RAPD) analyses to clarify the status issue. Nine arbitrarily designed primers detected 160 polymorphisms in 174 pool frogs from 11 European locations. Polymorphism levels varied widely, being lowest in the northern populations and highest in the south. As with many isolated populations, the peninsular and insular populations of Sweden, Norway and Britain showed relatively little polymorphism. Principal component and cluster analysis showed clear geographical groupings. The Norfolk, Norwegian and Swedish individuals formed a closely related group − a northern clade, substantiating native status for the Norfolk population, which, interestingly, had idiosyncratic features suggestive of a distinctive evolutionary history. Phylograms constructed from RAPD data were consistent with an unexpected postglacial colonization route, in which the northern clade derived from migration out of Italy, via Hungary and Poland, though cryptic glacial refugia in Eastern Europe are an alternative explanation. Our RAPD analyses concur with a parallel microsatellite investigation. Both genetic studies and bioacoustic and archaeozoological findings support native status for Norfolk pool frogs and have prompted a programme for re-establishing the northern clade in England.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 85 , 41–51.     

Population genetics, phylogeography and speciation of Cystodytes (Ascidiacea) in the western Mediterranean Sea

Several morphotypes that so far have been attributed to the allegedly cosmopolitan ascidian Cystodytes dellechiajei occur in the Mediterranean Sea. Colour variation is the difference most frequently reported. In this study, we addressed the genetic structure of this ascidian in relation to geographical location and colour morph. Partial sequences of the gene cytochrome  c oxidase subunit 1 (COI) were obtained from seven populations of the western Mediterranean, encompassing eight colour varieties. All population genetic analyses (exact test, pairwise F _ST, hierarchical analysis of molecular variance, multidimensional scaling, nested clade analysis) indicated clearly that differences between colour morphs are large enough to obscure any geographical differentiation when colours are combined within localities. When variance due to colour divergence was removed, however, a significant geographical variability between localities remained. The genetic divergence between the colour morphs analysed was significant in comparisons of the brown and purple forms with the others, but not among the green, blue, and white morphs. Phylogeographic analyses suggest that population fragmentation and range expansions have shaped the present-day distribution of the haplotypes. Taken together with existing chemotype information, our results indicate that several species are present in the area, and that a thorough revision of the genus is necessary.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 203–214.     

Genetic variation of Saxifraga paniculata Mill. (Saxifragaceae): molecular evidence for glacial relict endemism in central Europe

Saxifraga paniculata Mill. is an amphi-atlantic species that is widely distributed in the Alps but also occurs with disjunct populations in central Europe. These isolated populations are considered to be glacial relicts. In the study presented here, we analysed the genetic variation within and between populations of Saxifraga paniculata in central Europe to test whether the molecular data give evidence for the supposed relict endemism. We used RAPD analysis and the analysis of molecular variance (AMOVA) technique to investigate 30 populations of Saxifraga paniculata from different locations in central Europe and adjacent geographical areas. In the RAPD analysis, 319 fragments could be amplified of which 91.2% were polymorphic. The percentage of polymorphic bands within populations correlated significantly with population size, indicating a higher level of inbreeding in small populations. AMOVA revealed 43.60% of the variation within populations, only 15.45% between populations within locations, and 40.95% between locations. Genetic distance between locations (Φ_ST) correlated significantly with the geographical distance between locations, giving evidence for geographical isolation. In an UPGMA cluster analysis, based on RAPD data, the populations were grouped together according to their location. The results exhibit a strong genetic differentiation which is obviously due to genetic drift in the isolated populations. Our study therefore gives evidence for glacial relict endemism of Saxifraga paniculata in central Europe.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80, 11–21.     

Two approaches for the selection of Relevant Genetic Units for Conservation in the narrow European endemic steppe plant Boleum asperum (Brassicaceae)

Several methods based on population biology, biogeography, ecology, and genetics have been traditionally used for the identification of units for conservation below the species level. We use a combination of two methods based on population genetic structure estimators and on probabilities of loss of rare alleles to identify the Relevant Genetic Units for Conservation (RGUCs). The aims were to assess the genetic diversity and population structure of the endemic steppe plant Boleum asperum (Brassicaceae), and to determine how many and which populations significantly represent the total genetic diversity and the rarest allelic variation. Despite the high amplified fragment length polymorphism genetic diversity values detected in B. asperum ( h _T = 0.744), caused probably by its hexaploidy and allogamy, moderate spatial genetic differentiation was detected among populations (< 20%) and geographical ranges (> 13%), suggesting the existence of an ancestral continuous distribution range that was fragmented into separate 'islands' in more recent historical times. Five RGUCs, accounting for the 85.10% of the total genetic variation and representative of the entire geographical distribution of the species, were selected for in situ conservation. Ex situ conservation is proposed to complement the preservation of B. asperum . This method of objective selection of populations may be applied to other candidate taxa for conservation with prior adjustment of the threshold values of diversity required for effective protection of each particular species.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 341–354.     

Morphological variation in house mice from the Robertsonian polymorphism area of Barcelona

Morphometric variation in the Robertsonian polymorphism zone of Barcelona of Mus musculus domesticus was studied by geometric morphometrics. This system is characterized by populations of reduced diploid number (2 n  = 27–39) surrounded by standard populations (2 n  = 40). We investigated the morphological variation in mice from this area, as well as the effect of geographical distance and karyotype on this variation. We also investigated the degree of co-variation between the two functional units of the mandible to explore the origin of this system (primary intergradation or secondary contact). The size and shape of the cranium, mandible and scapula were analysed for 226 specimens grouped by population, chromosome number and structural heterozygosity. Size was estimated as the centroid size, and shape was estimated after Procrustes superimposition. No significant differences in size between populations or chromosomal groups were detected. Diploid number, structural heterozygosity and local geographical isolation contributed to the differentiation in shape. Morphological differentiation between standard mice and Robertsonian specimens was observed, suggesting genetic isolation between these groups. Co-variation between the ascending ramus and alveolar region of the mandible was quantified by the trace correlation between landmark subsets of these modules. The trace values showed an ascending trend, correlated with the distance from the centre of the polymorphism area, a pattern consistent with a primary intergradation scenario.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 555–570.     

Parnassia palustris: a genetically diverse species in Scandinavia

Patterns of variation at nine enzyme loci were examined in 528 plants representing diploid and tetraploid populations of Parnassia palustris s. l. in Europe to assess genetic variation patterns and migration history. Half of the plants showed a unique multilocus phenotype and 75% of all phenotypes occurred only in Scandinavia. Diploid populations showed similar levels of genetic diversity as other widespread outbreeding species with animal-mediated pollination and F -statistics indicated excessive heterozygosity and low rates of gene flow among them. In spite of dramatic population histories caused by the ice ages, diploid populations have maintained the same genetic diversity in Scandinavia as in central and southern Europe. Northern populations have apparently been established through the gradual advance of genetically variable populations and patterns of variation at individual loci indicate different migration routes, from the south-south-west and the east-north-east, respectively. The data strongly support a repeated autoploid origin of the tetraploid cytotype which has been much more successful than the diploid progenitors in colonizing new land since the last ice age. High genetic diversity in Scandinavia has apparently been obtained by a combination of immigration of plants from different source areas and recurrent formation of autotetraploids from diploid progenitors.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 347−372.     

The roles of pre‐ and post‐hatching growth rates in generating a latitudinal cline of body size in the eastern fence lizard (Sceloporus undulatus)

Countergradient variation in norms of reaction can dampen the direct effects of environmental influences on phenotypic traits, allowing phenotypic similarity among populations despite exposure to different environmental conditions. Such norms of reaction may occur at any phase of the life‐history (e.g. growth rates during both embryonic and postembryonic stages may influence geographical variation in adult body size). We collected gravid female lizards (Sceloporus undulatus) from northern (Indiana), central (Mississippi), and southern (Florida) populations, spanning almost the full latitudinal range of the species. Adult females from the southern population were smaller. Intrinsic growth rates of hatchlings were higher for the central population than for the other two populations. This pattern does not parallel the countergradient variation previously found in embryonic developmental rates among these populations. Earlier hatching enhanced survival rates of juveniles to a similar degree among populations, although juvenile survival rates in the field generally increase with latitude in this species. Our data reveal geographical variation in the ways in which intrinsic developmental/growth rates and survival shift during ontogeny, and suggest that latitudinal patterns in adult body size (such as Bergmann's rule) can result from both faster growth, and longer periods of growth. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 202–209.     

Allozymic differentiation of Tunisian populations of Androctonus species and Buthus occitanus (Scorpiones: Buthidae)

We examined the population structure and phylogeny of Buthus occitanus (Amoreux, 1789), Androctonus amoreuxi (Audouin & Savigny 1812) and Androctonus australis (Linnaeus, 1758) in Tunisia, using horizontal starch gel and polyacrylamide gel electrophoresis to resolve allozymes at 18 loci. Populations of B. occitanus and A. amoreuxi showed little genetic variation, whereas A. australis populations showed moderate genetic variation. Moreover, despite the restricted dispersal abilities of these species, the allozyme analysis indicated very low levels of intraspecific population differentiation. The Island model of population differentiation best fitted the intraspecific variation, both for mainland populations and for the slightly more differentiated populations from two Mediterranean islands. No diagnostic, fixed alleles were observed between the species of Androctonus , which concurs with the results of nuclear ribosomal DNA analysis. Two subspecies of A. australis , A. a. garzonii Goyffon & Lamy, 1973 and A. a. hector Vachon, 1948, were not resolved by a phylogenetic analysis of the allozyme data. The most likely reasons for the slight population differentiation are either low mutation rates or recent range extensions promoted by human activities. The possibility of indirect gene flow between Androctonus species should also be explored.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 255–265.     

Conservation genetics of the endangered red deer from Sardinia and Mesola with further remarks on the phylogeography of Cervus elaphus corsicanus

Red deer Cervus elaphus of the endangered populations from Sardinia and Mesola Wood, northern Italy, were analysed for genetic variation at 531 bp of the mitochondrial control region and 12 polymorphic nuclear microsatellite loci. A phylogenetic analysis was conducted including additional data from the literature to gain insight into the phylogeographical origin of the Sardinian subspecies C. e. corsicanus . Microsatellite variation was low in both populations but Sardinia showed comparatively high variability at the control region. Management recommendations are discussed. In particular, the Mesola red deer, the only remaining indigenous Italian population, ought to be managed to increase the effective population size and should be subdivided into two or more populations. As to the phylogeography of the Sardinian population, microsatellite data favoured mainland Italy as the place of origin in that Sardinia and Mesola showed the smallest distance values and were paired together in trees with high bootstrap support. However, the mitochondrial data only partially confirmed this conclusion but showed great similarity between Sardinian and Spanish red deer. Possible explanations for this discrepancy and general limits of mitochondrial sequences in resolving demographic and biogeographical processes of the recent past are discussed.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 691–701.     

青藏高原垂穗披碱草遗传变异的地理因素分析

采用等位酶标记对我国青藏高原地区垂穗披碱草的9个种群进行遗传变异和系统关系分析.结果表明,不同种群间遗传距离范围在0.010 6-0.377 8,种群间遗传距离和地理环境关系密切.采用聚类分析和二维、三维Mantel检验,对青藏高原垂穗披碱草(Elymusnutans Griseb.)不同种群间遗传距离与环境条件的关系(纬度、经度和海拔)进一步分析发现,海拔和地理位置(纬度和经度)均明显影响垂穗披碱草种群遗传差异.种群间遗传距离和海拔(R=0.476 8)、地理位置(R=0.447 1)均呈现显著正相关,种群间遗传距离随着海拔、地理位置差距的增大而增加,但海拔是影响其遗传结构的最重要因素,其次是经纬度.