Genetic structure and gene flow in a metapopulation of an endangered plant species,Silene tatarica

We investigated the distribution of genetic variation within and between seven subpopulations in a riparian population of Silene tatarica in northern Finland by using amplified fragment length polymorphism (AFLP) markers. A Bayesian approach-based clustering program indicated that the marker data contained not only one panmictic population, but consisted of seven clusters, and that each original sample site seems to consist of a distinct subpopulation. A coalescent-based simulation approach shows recurrent gene flow between subpopulations. Relative high FST values indicated a clear subpopulation differentiation. However, amova analysis and UPGMA-dendrogram did not suggest any hierarchical regional structuring among the subpopulations. There was no correlation between geographical and genetic distances among the subpopulations, nor any correlation between the subpopulation census size and amount of genetic variation. Estimates of gene flow suggested a low level of gene flow between the subpopulations, and the assignment tests proposed a few long-distance bidirectional dispersal events between the subpopulations. No apparent difference was found in within-subpopulation genetic diversity among upper, middle and lower regions along the river. Relative high amounts of linkage disequilibrium at subpopulation level indicated recent population bottlenecks or admixture, and at metapopulation levels a high subpopulation turnover rate. The overall pattern of genetic variation within and between subpopulations also suggested a 'classical' metapopulation structure of the species suggested by the ecological surveys.     

Population structure and genetic differentiation associated with breeding history and selection in tomato (Solanum lycopersicum L.)

Tomato (Solanum lycopersicum L.) has undergone intensive selection during and following domestication. We investigated population structure and genetic differentiation within a collection of 70 tomato lines representing contemporary (processing and fresh-market) varieties, vintage varieties and landraces. The model-based Bayesian clustering software, STRUCTURE, was used to detect subpopulations. Six independent analyses were conducted using all marker data (173 markers) and five subsets of markers based on marker type (single-nucleotide polymorphisms, simple sequence repeats and insertion/deletions) and location (exon and intron sequences) within genes. All of these analyses consistently separated four groups predefined by market niche and age into distinct subpopulations. Furthermore, we detected at least two subpopulations within the processing varieties. These subpopulations correspond to historical patterns of breeding conducted for specific production environments. We found no subpopulation within fresh-market varieties, vintage varieties and landraces when using all marker data. High levels of admixture were shown in several varieties representing a transition in the demarcation between processing and fresh-market breeding. The genetic clustering detected by using the STRUCTURE software was confirmed by two statistics, pairwise F(st) (θ) and Nei's standard genetic distance. We also identified a total of 19 loci under positive selection between processing, fresh-market and vintage germplasm by using an F(st)-outlier method based on the deviation from the expected distribution of F(st) and heterozygosity. The markers and genome locations we identified are consistent with known patterns of selection and linkage to traits that differentiate the market classes. These results demonstrate how human selection through breeding has shaped genetic variation within cultivated tomato.     

用分子标记揭示植物随机大居群中亚居群的遗传结构——茅栗自然居群空间遗传结构的SSR分析

采用微卫星标记对茅栗(Castanea sequinii)随机大居群以及其中各亚居群的遗传结构进行了空间自相关分析,以探讨植物自然居群内遗传变异的分布特征及其形成机制。通过9对微卫星引物所产生的119个多态位点,测定了大别山区域内茅栗居群以及各亚居群的空间自相关系数Moran's I值。结果表明:大别山分布的野生茅栗为一个缺乏空间结构的随机大居群,茅栗亚居群之间频繁的花粉流削弱了地理隔离导致的遗传漂变或分化作用在维系居群随机遗传结构中具有的重要作用。但是,在接近亚居群大小的地域范围内(0.228 km)具有一定的空间结构,即小地域尺度中的亚居群存在着空间遗传结构。取样的3个亚居群在小格局范围内都存在一定的空间结构,遗传变异基本上呈非随机分布,在短距离内(61 m)3个亚居群一致表现出不同程度的显著正相关,而随着距离的增加,Moran's I值虽然在不同亚居群间存在一定差异变化,但是总体而言趋向预期值,即不存在空间结构,说明其遗传变异在亚居群内只是在短距离内形成一定的空间结构。研究认为有限的种子散播以及微生境选择等因素可能是产生这种小格局的遗传结构的主要原因。上述研究结果有助于进一步了解植物随机大居群的进化历史和生态过程,同时也为栗属植物中国特有种的保育策略提供了科学依据。     

Inferring population history from fine-scale spatial genetic analysis in Oryza rufipogon (Poaceae)

Determining the genetic structure of an in situ conserved population can provide insight into the dynamics of population genetic processes associated with successful plant conservation. We used 21 microsatellite loci to analyse the genetic relationships among individuals (n = 813) collected from a small Oryza rufipogon population conserved since 1993 in Hunan Province of China. The analysis revealed four distinct genetic subpopulations (F(ST) = 0.145) without geographic isolation. One subpopulation was composed of possible introgressed individuals, two subpopulations were composed of seed recruits and their descendants, and the fourth subpopulation consisted of reintroduced individuals, seed recruits and their descendants. Positive spatial genetic structures were detected by spatial autocorrelation statistics at the population (c. 63 m) and subpopulation levels (11-30 m), but the degree of autocorrelation was stronger at the population level. These results showed that prejudging the cryptic structure is important before autocorrelation analysis for the entire population. Our study suggests that population history can be a significant determinant on population structure for plant restoration projects.     

Admixture promotes genetic variation in bottlenecked moose populations in eastern Poland

Human activity has led to severe bottlenecks in many wildlife species in the recent past. This usually increases the strength of genetic drift, leading to loss of genetic variation. Gene flow may however counteract the genetic consequences of small population size. Using 11 of 38 tested microsatellite loci and five moose populations in eastern Poland, we investigated the effects of two phenomena: bottlenecks that occurred in the nineteenth century and the first half of twentieth century, and admixture after moose populations expanded demographically and spatially in eastern Poland after the Second World War. The statistical tests indicated a recent bottleneck in all the studied samples with respect to H _E and low Garza–Williamson index values. The Biebrza population, which consists of autochthonous moose representing a branch of the Central Europe mitochondrial DNA (mtDNA) clade and immigrants belonging to the Ural clade, is one of the most variable populations of this species. AMOVA, PCA, and STRUCTURE analyses all revealed significant population structuring, with most probable existence of K?=?2 genetically distinct clusters that exhibited a relatively high level of admixture. Analysis of recent dispersal rates demonstrated that population from the Biebrza Valley may supply individuals to the other four studied moose populations. We also found female-biased sex ratio in nonharvested moose populations inhabiting eastern Poland.     

Differential influences of local subpopulations on regional diversity and differentiation for greater sage‐grouse (Centrocercus urophasianus)

The distribution of spatial genetic variation across a region can shape evolutionary dynamics and impact population persistence. Local population dynamics and among‐population dispersal rates are strong drivers of this spatial genetic variation, yet for many species we lack a clear understanding of how these population processes interact in space to shape within‐species genetic variation. Here, we used extensive genetic and demographic data from 10 subpopulations of greater sage‐grouse to parameterize a simulated approximate Bayesian computation (ABC) model and (i) test for regional differences in population density and dispersal rates for greater sage‐grouse subpopulations in Wyoming, and (ii) quantify how these differences impact subpopulation regional influence on genetic variation. We found a close match between observed and simulated data under our parameterized model and strong variation in density and dispersal rates across Wyoming. Sensitivity analyses suggested that changes in dispersal (via landscape resistance) had a greater influence on regional differentiation, whereas changes in density had a greater influence on mean diversity across all subpopulations. Local subpopulations, however, varied in their regional influence on genetic variation. Decreases in the size and dispersal rates of central populations with low overall and net immigration (i.e. population sources) had the greatest negative impact on genetic variation. Overall, our results provide insight into the interactions among demography, dispersal and genetic variation and highlight the potential of ABC to disentangle the complexity of regional population dynamics and project the genetic impact of changing conditions.     

Genetic Structure and Evidence of a Local Bottleneck in Moose in Sweden

ABSTRACT The moose (Alces alces) is the most intensely managed game species in Sweden. Despite the biological and socioeconomical importance of moose, little is known of its population genetic structure. We analyzed 132 individuals from 4 geographically separate regions in Sweden for genetic variability at 6 microsatellite loci. We found evidence of strong substructuring and restricted levels of gene flow in this potentially mobile mammal. F_ST values were around 10%, and assignment tests indicated 3 genetically distinct populations over the study area. Spatial autocorrelation analysis provided a genetic patch size of approximately 420 km, implying that moose less than this distance apart are genetically more similar than 2 random individuals. Allele and genotype frequency distributions suggested a recent bottleneck in southern Sweden. Results indicate that moose may be more genetically divergent than currently anticipated, and therefore, the strong hunting pressure that is maintained over all of Sweden may have considerable local effects on genetic diversity. Sustainable moose hunting requires identification of spatial genetic structure to ensure that separate, genetically distinct subpopulations are not overharvested.     

Molecular diagnosis for a Tamarix species from two reclaimed lands along the Yellow Sea in Korea inferred from genome wide SNP markers

The taxonomy and phylogenetic relationships of related taxa are important for understanding the biology of a species. Also, spatial distribution of genetic variation may offer insights into history of range shifts and demographic changes. The genus Tamarix L. from the Old World is a taxonomically challenging group that has widely expanded its range in the recent past. We examined genomic diversity patterns and the taxonomic identities of Korean Tamarix species whose taxonomy has remained unresolved. We used a total of 1773 SNP data from genotyping by sequencing for 37 Tamarix plants representing two species; T. chinensis and T. ramosissima to infer species delimitation and the geographic distribution of genomic diversity. Clustering (STRUCTURE; PCA, neighbor joining) and phylogenetic tree results indicated that the two morphologically similar species T. chinensis and T. ramosissima are genetically distinct and the two Korean populations (Sihwa & Songdo) are clustered closely with T. chinensis. Approximate Bayesian Computation based hypothesis testing results suggested that one of the two Korean populations, Songdo might have primarily been derived from the native area, China, followed by range expansion to Sihwa with a secondary admixture event between an established population, Songdo, and a native population, Beijing.     

Subpopulation genetic structure of a plant panmictic population of Castanea sequinii as revealed by microsatellite markers

Castanea squinii Dode,an endemic tree widely distributed in China,plays an important role both in chestnut breeding and forest ecosystem function.The spatial genetic structure within and among populations is an important part of the evolutionary and ecological genetic dynamics of natural populations,and can provide insights into effective conservation of genetic resources.In the present study,the spatial genetic structure of a panmictic natural population of C.sequinii in the Dabie Mountain region was investigated using microsatellite markers.Nine prescreened microsatellite loci generated 29-33 alleles each,and were used for spatial autocorrelation analysis.Based on Moran's I coefficient,a panmictic population of C.sequinii in the Dabie Mountain region was found to be lacking a spatial genetic structure.These results suggest that a high pollen-mediated gene flow among subpopulations counteract genetic drift and/or genetic differentiation and plays an important role in maintaining a random and panmictic population structure in C.sequinii populations.Further,a spatial genetic structure was detected in each subpopulation's scale (0.228 km),with all three subpopulations showing significant fine-scale structure.The genetic variation was found to be nonrandomly distributed within 61 m in each subpopulation (Moran's I positive values).Although Moran's I values varied among the different subpopulations,Moran's I in all the three subpopulations reached the expected values with an increase in distances,suggesting a generally patchy distribution in the subpopulations.The fine-scale structure seems to reflect restricted seed dispersal and microenvironment selection in C.sequinii.These results have important implications for understanding the evolutionary history and ecological process of the natural population of C.sequinii and provide baseline data for formulating a conservation strategy of Castanea species.     

A hierarchical Bayesian Beta regression approach to study the effects of geographical genetic structure and spatial autocorrelation on species distribution range shifts

Global climate change (GCC) may be causing distribution range shifts in many organisms worldwide. Multiple efforts are currently focused on the development of models to better predict distribution range shifts due to GCC. We addressed this issue by including intraspecific genetic structure and spatial autocorrelation (SAC) of data in distribution range models. Both factors reflect the joint effect of ecoevolutionary processes on the geographical heterogeneity of populations. We used a collection of 301 georeferenced accessions of the annual plant Arabidopsis thaliana in its Iberian Peninsula range, where the species shows strong geographical genetic structure. We developed spatial and nonspatial hierarchical Bayesian models (HBMs) to depict current and future distribution ranges for the four genetic clusters detected. We also compared the performance of HBMs with Maxent (a presence‐only model). Maxent and nonspatial HBMs presented some shortcomings, such as the loss of accessions with high genetic admixture in the case of Maxent and the presence of residual SAC for both. As spatial HBMs removed residual SAC, these models showed higher accuracy than nonspatial HBMs and handled the spatial effect on model outcomes. The ease of modelling and the consistency among model outputs for each genetic cluster was conditioned by the sparseness of the populations across the distribution range. Our HBMs enrich the toolbox of software available to evaluate GCC‐induced distribution range shifts by considering both genetic heterogeneity and SAC, two inherent properties of any organism that should not be overlooked.     

Fine-scale genetic structure in Ethiopian wolves imposed by sociality,migration, and population bottlenecks

We used demographic, spatial, and microsatellite data to assess fine-scale genetic structure in Ethiopian wolves found in the Bale Mountains and evaluated the impact of historical versus recent demographic processes on genetic variation. We applied several analytical methods, assuming equilibrium and nonequilibrium conditions, to assess demography and genetic structure. Genetic variation (H _E = 0.584–0.607, allelic richness = 4.2–4.3) was higher than previously reported for this species and genetic structure was influenced by geography and social structure. Statistically significant F _ST values (0.06–0.08) implied differentiation among subpopulations. STRUCTURE analyses showed that neighbouring packs often have shared co-ancestry and spatial autocorrelation showed higher genetic similarity between individuals within packs and between individuals in neighbouring packs compared to random pairs of individuals. Recent effective population sizes were lower than 2n (where n is the number of packs) and lower than the number of breeding individuals with N _e /N ratios near 0.20. All subpopulations have experienced bottlenecks, one occurring due to a rabies outbreak in 2003. Nevertheless, differentiation among these subpopulations is consistent with long-term migration rates and fragmentation at the end of the Pleistocene. Enhanced drift due to population bottlenecks may be countered by higher migration into disease-affected subpopulations. Contemporary factors such as social structure and population bottlenecks are clearly influencing the level and distribution of genetic variation in this population, which has implications for its conservation.     

Spatial arrangement and genetic structure in Gentianella aspera in a regional, local, and temporal context

Gentianella aspera is a biennial plant of various nutrient-poor grasslands that has become rare in the landscapes outside the Alps of eastern Austria. Using AFLP fingerprinting we investigated: (1) effects of spatial structure on genetic structure in a large vineyard population that is confined to the embankments separating the grapevines; (2) temporal variation in genetic diversity and structure in this population; (3) relationships with other populations in a regional context. On the regional scale, moderate isolation by distance among populations was revealed by a Mantel test. Bayesian analysis of population structure indicated three spatially distinct gene pools and an additional one within the vineyard population. Within this population, spatial autocorrelation analysis revealed a positive correlation between genetic and spatial distance up to 50 m. Patterns found by PCoA were not in line with a priori defined subpopulations and indicated substantial gene flow across embankments. AMOVA revealed low differentiation among both the subpopulations that were found on the linear embankments and among two local groups of these subpopulations. We found, however, striking differences in the among-group variation between the 2 years, i.e., between two local groups within the generations and between those groups among generations. This was due to the highly variable larger group of the younger generation, in which an additional gene pool was identified by Bayesian analysis of population structure. Based on these results we discuss scenarios of local and regional dynamics within and among G. aspera populations.     

Hierarchical population structure in greater sage-grouse provides insight into management boundary delineation

Understanding population structure is important for guiding ongoing conservation and restoration efforts. The greater sage-grouse (Centrocercus urophasianus) is a species of concern distributed across 1.2 million km² of western North America. We genotyped 1499 greater sage-grouse from 297 leks across Montana, North Dakota and South Dakota using a 15 locus microsatellite panel, then examined spatial autocorrelation, spatial principal components analysis, and hierarchical Bayesian clustering to identify population structure. Our results show that at distances of up to ~240 km individuals exhibit greater genetic similarity than expected by chance, suggesting that the cumulative effect of short-range dispersal translates to long-range connectivity. We found two levels of hierarchical genetic subpopulation structure. These subpopulations occupy significantly different elevations and are surrounded by divergent vegetative communities with different dominant subspecies of sagebrush, each with its own chemical defense against herbivory. We propose five management groups reflective of genetic subpopulation structure. These genetic groups are largely synonymous with existing priority areas for conservation. On average, 85.8 % of individuals within each conservation priority area assign to a distinct subpopulation. Our results largely support existing management decisions regarding subpopulation boundaries.     

The contemporary genetic pattern of European moose is shaped by postglacial recolonization,bottlenecks, and the geographical barrier of the Baltic Sea

To investigate genetic diversity and the population structure of the European moose (Alces alces), we analyzed 14 microsatellite loci for 694 samples collected across 16 localities. The highest genetic diversity was detected in Belarus and Russia and the lowest was found in Scandinavia. Two major genetic clusters existed, Scandinavian and continental, and some further spatial structure was detected. There was high concordance between the spatial distribution of microsatellite clusters analyzed in the present study and previously recognized mitochondrial DNA clades of moose. The split of genetic lineages calculated using approximate Bayesian computation (ABC) occurred at the beginning of the Last Glacial Maximum: approximately 29 000 and 28 000 years BP. A range‐wide bottleneck detected by ABC took place 1800–1200 years BP, although a more recent decline in moose numbers was also documented in the 18th to early 20th Century. Genetic differentiation in European moose increased with geographical distance, and the Baltic Sea appeared to be a barrier to gene flow. We conclude that isolation in different glacial refugia, postglacial colonization, and declines of range and numbers in Holocene shaped the present pattern of genetic diversity of European moose. Based on genetic divergence and a lack of apparent gene flow, the contemporary Scandinavian and continental subpopulations should be treated as separate management units.     

Moose body mass variation revisited: disentangling effects of environmental conditions and genetics

Large-scale geographical variation in phenotypic traits within species is often correlated to local environmental conditions and population density. Such phenotypic variation has recently been shown to also be influenced by genetic structuring of populations. In ungulates, large-scale geographical variation in phenotypic traits, such as body mass, has been related to environmental conditions and population density, but little is known about the genetic influences. Research on the genetic structure of moose suggests two distinct genetic lineages in Norway, structured along a north-south gradient. This corresponds with many environmental gradients, thus genetic structuring provides an additional factor affecting geographical phenotypic variation in Norwegian moose. We investigated if genetic structure explained geographical variation in body mass in Norwegian moose while accounting for environmental conditions, age and sex, and if it captured some of the variance in body mass that previously was attributed to environmental factors. Genetic structuring of moose was the most important variable in explaining the geographic variation in body mass within age and sex classes. Several environmental variables also had strong explanatory power, related to habitat diversity, environmental seasonality and winter harshness. The results suggest that environmental conditions, landscape characteristics, and genetic structure should be evaluated together when explaining large-scale patterns in phenotypic characters or life history traits. However, to better understand the role of genetic and environmental effects on phenotypic traits in moose, an extended individual-based study of variation in fitness-related characters is needed, preferably in an area of convergence between different genetic lineages.     

A Markov chain Monte Carlo approach for joint inference of population structure and inbreeding rates from multilocus genotype data

Nonrandom mating induces correlations in allelic states within and among loci that can be exploited to understand the genetic structure of natural populations (Wright 1965). For many species, it is of considerable interest to quantify the contribution of two forms of nonrandom mating to patterns of standing genetic variation: inbreeding (mating among relatives) and population substructure (limited dispersal of gametes). Here, we extend the popular Bayesian clustering approach STRUCTURE (Pritchard et al. 2000) for simultaneous inference of inbreeding or selfing rates and population-of-origin classification using multilocus genetic markers. This is accomplished by eliminating the assumption of Hardy-Weinberg equilibrium within clusters and, instead, calculating expected genotype frequencies on the basis of inbreeding or selfing rates. We demonstrate the need for such an extension by showing that selfing leads to spurious signals of population substructure using the standard STRUCTURE algorithm with a bias toward spurious signals of admixture. We gauge the performance of our method using extensive coalescent simulations and demonstrate that our approach can correct for this bias. We also apply our approach to understanding the population structure of the wild relative of domesticated rice, Oryza rufipogon, an important partially selfing grass species. Using a sample of n = 16 individuals sequenced at 111 random loci, we find strong evidence for existence of two subpopulations, which correlates well with geographic location of sampling, and estimate selfing rates for both groups that are consistent with estimates from experimental data (s approximately 0.48-0.70).     

Patchy population structure in a short-distance migrant: evidence from genetic and demographic data

Species often occur in subdivided populations as a consequence of spatial heterogeneity of the habitat. To describe the spatial organization of subpopulations, existing theory proposes three main population models: patchy population, metapopulation and isolated populations. These models differ in their predicted levels of connectivity among subpopulations, and in the risk that a subpopulation will go extinct. However, spatially discrete subpopulations are commonly considered to be organized as metapopulations, even though explicit tests of metapopulation assumptions are rare. Here, we test predictions of the three models on the basis of demographic and genetic data, a combined approach so far surprisingly little used in mobile organisms. From 2002 to 2005, we studied nine subpopulations of the wetland-restricted reed bunting ( Emberiza schoeniclus ) in the southeastern part of the Canton Zurich (Switzerland), from which local declines of this species have been reported. Here, wetlands are as small as 2.7 ha and separated through intensively used agricultural landscapes. Demographic data consisted of dispersal of colour-banded individuals among subpopulations, immigration rates and extinction-/recolonization dynamics. Genetic data were based on the distribution of genetic variability and gene flow among subpopulations derived from the analysis of nine microsatellite loci. Both demographic and genetic data revealed that the patchy population model best described the spatial organization of reed bunting subpopulations. High levels of dispersal among subpopulations, high immigration into the patchy population, and genetic admixture suggested little risk of extinction of both subpopulations and the entire patchy population. This study exemplifies the idea that spatially discrete subpopulations may be organized in ways other than a metapopulation, and hence has implications for the conservation of subpopulations and species.     

Spatial effects and rare outcrossing events in Medicago truncatula (Fabaceae)

In order to elucidate the mechanisms underlying the large amount of RAPD polymorphism found in 1990 in a population of the selfing annual Medicago truncatula GAERTN. (Fabaceae), we have analysed most of the individuals (n = 363) from the same population 6 years later using microsatellite loci. We confirm the result of the earlier study, namely that this population is very polymorphic and highly subdivided, with approximately 37% of the variance distributed among subpopulations, only 50 m apart one from another. We use standard F-statistics analyses, linkage disequilibria, minimum spanning network, multilocus assignment tests and spatial autocorrelation analyses to test the hypotheses that spatial structure and outcrossing events are involved in maintaining the large amount of genetic diversity at the level of each subpopulation. Interestingly, fine-scale spatial structure could be observed in only one subpopulation suggesting that other mechanisms are acting elsewhere. To the best of our knowledge, this is the first study of fine spatial genetic structure in a predominantly selfing species.     

Local differentiation and gene dispersal distances in a Danish population of Armaria maritima

In a continuously distributed population of the self-incompatible species Armeria maritima , nine artificially delimited subpopulations were sampled in a transect with a length of 1300 m. Genetic variation was quantified with enzyme electrophoresis, which revealed five polymorphic loci. The genotypic distribution within subpopulations accorded to Hardy-Weinberg proportions, but revealed a Wahlund effect at one of the loci when the total population was considered. The Wahlund effect was supported by significant differences in allele frequencies among the nine subpopulations. The differentiation was low with a F_ST value of 0.028, which is much smaller than the previously reported value of 0.18 for 17 geographically separated Danish populations of this species. The low differentiation of the subpopulations was also revealed by an assignment test. In this test, the multilocus genotype of an individual is used to assign it to the subpopulation it has the highest likelihood to appear in. With this test, a lower percentage of individuals were assigned to the subpopulation of origin (24) than was seen with assignment of individuals to populations in Denmark (34). No abrupt changes in allele frequencies were observed. A spatial autocorrelation analysis suggested a breeding patch size of 500–700 m in diameter along the transect.     

Local genetic population structure in an endangered plant species, Silene tatarica (Caryophyllaceae)

Genetic substructuring in plant populations may evolve as a consequence of sampling events that occur when the population is founded or regenerated, or if gene dispersal by pollen and seeds is restricted within a population. Silene tatarica is an endangered, perennial plant species growing along periodically disturbed riverbanks in northern Finland. We investigated the mechanism behind the microspatial genetic structure of S. tatarica in four subpopulations using amplified fragment length polymorphism markers. Spatial autocorrelation revealed clear spatial genetic structure in each subpopulation, even though the pattern diminished in older subpopulations. Parentage analysis in an isolated island subpopulation indicated a very low level of selfing and avoidance of breeding between close relatives. The mean estimated pollen dispersal distance (24.10 m; SD = 10.5) was significantly longer and the mean seed dispersal distance (9.07 m; SD = 9.23) was considerably shorter than the mean distance between the individuals (19.20 m; SD = 13.80). The estimated indirect and direct estimates of neighbourhood sizes in this subpopulation were very similar, 32.1 and 37.6, respectively. Our results suggested that the local spatial genetic structure in S. tatarica was attributed merely to the isolation-by-distance process rather than founder effect, and despite free pollen movement across population, restricted seed dispersal maintains local genetic structure in this species.