Population divergence in the amphicarpic species Amphicarpaea edgeworthii Benth. (Fabaceae): microsatellite markers and leaf morphology

Comparative analyses of the genetic differentiation in microsatellite markers ( F _ST) and leaf morphology characters ( Q _ST) of Amphicarpaea edgeworthii Benth. were conducted to gain insight into the roles of random processes and natural selection in the population divergence. Simple sequence repeat analyses on 498 individuals of 19 natural populations demonstrate that a significant genetic differentiation occurs among populations (mean F _ST = 0.578), and A. edgeworthii is a highly self-fertilized species (mean selfing rate s  = 0.989). The distribution pattern of genetic diversity in this species shows that central populations possess high genetic diversity (e.g. population WL with H _E = 0.673 and population JG with H _E = 0.663), whereas peripheral ones have a low H _E as in population JD (0.011). The morphological divergence of leaf shape was estimated by the elliptical Fourier analysis on the data from 11 natural and four common garden populations. Leaf morphology analyses indicate the morphological divergence does not show strong correlation with the genetic differentiation ( R  = 0.260, P  = 0.069). By comparing the 95% confidence interval of Q _ST with that of F _ST, Q _ST values for five out of 12 quantitative traits are significantly higher than the average F _ST value over eight microsatellite loci. The comparison of F _ST and Q _ST suggests that two kinds of traits can be driven by different evolutionary forces, and the population divergence in leaf morphology is shaped by local selections.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 505–516.     

Genetic diversity and genetic structure of populations of Ranunculus japonicus Thunb. (Ranunculaceae)

Abstract In order to clarify the genetic diversity and population structure of Ranunculus japonicus , allozymic analysis was conducted on 60 populations in southwestern Japan. Considerable genetic variati ons were detected among the populations of R. japonicus . The genetic diversities within species ( H _es = 0.215) and within populations ( H _ep = 0.172) were slightly higher than those of other perennial herbs with widespread distribution and outcrossing plants. Significantly higher values of fixation index were detected in some populations, which might have arisen from restricted mating partners. The majority of genetic variation (approx. 80%) resided within a population and a moderate level of genetic differentiation ( G _ST = 0.203) was observed among populations. The F _ST value (0.203) suggests the existence of a substantial population structure in this species. The highly significant correlation between geographic distance and F _ST values indicates that isolation by distance has played an important role in the construction of the genetic structure of this species.     

Population genetic structure in Myrtus communis L. in a chronically fragmented landscape in the Mediterranean: can gene flow counteract habitat perturbation?

Ancient managed landscapes provide ideal opportunities to assess the consequences of habitat fragmentation on the patterns of genetic diversity and gene flow in long-lived plant species. Using amplified fragment length polymorphism (AFLP) and allozyme markers, we quantified seed-mediated gene flow and population genetic diversity and structure in 14 populations of Myrtus communis (myrtle), a common endozoochorous shrub species of forest patches in lowland agricultural Mediterranean areas. Overall, allozyme diversity for myrtle was low (P₉₅   =   25%; A   =   1.411; H_e = 0.085) compared to other known populations, and a significant portion of populations (57%) had lower levels of allelic diversity and/or heterozygosity than expected at random, as shown by simulated resampling of the whole diversity of the landscape. We found significant correlations between allozyme variability and population size and patch isolation, but no significant inbreeding in any population. Genetic differentiation among populations for both allozyme and AFLP markers was significant (Φ_ST = 0.144 and Φ_ST = 0.142, respectively) but an isolation-by-distance pattern was not detected. Assignment tests on AFLP data indicated a high immigration rate in the populations ( ca. 20–22%), likely through effective seed dispersal across the landscape by birds and mammals. Our results suggest that genetic isolation is not the automatic outcome of habitat destruction since substantial levels of seed-mediated gene flow are currently detectable. However, even moderate rates of gene flow seem insufficient in this long-lived species to counteract the genetic erosion and differentiation imposed by chronic habitat destruction.     

Microsatellite variation and population structure of the moor frog (Rana arvalis) in Scandinavia

Several recent studies have found amphibian populations to be genetically highly structured over rather short geographical distances, and that the rate of genetically effective dispersal may differ between the sexes. However, apart from the common frog ( Rana temporaria ) little is known about the genetic structuring and sex-biased dispersal in northern European amphibians. We investigated the patterns of genetic diversity and differentiation within and among Scandinavian populations of the moor frog ( Rana arvalis ) using microsatellite markers. The genetic diversity within local R. arvalis populations was not a simple linear negative function of latitude but a convex one: genetic diversity peaked in mid-latitude populations, and declined thereafter dramatically towards the north. The average degree of genetic differentiation among populations ( F _ST = 0.14) was lower than that observed for the common frog ( F _ST = 0.21), though the pattern of isolation by distance was similar for both species. Contrary to common frogs, no evidence for female-biased dispersal was found. The results reinforce the view that amphibian populations are—in general—highly structured over relatively small geographical distances, even in comparatively recently colonized areas.     

Phylogeographic structure of Pinus strobiformis Engelm. across the Chihuahuan Desert filter-barrier

Aim  To explore the genetic and phylogeographic structure of a temperate forest species, Pinus strobiformis Englem., in a subtropical region in the context of climate change during the Pleistocene. It is expected that the colder conditions during glacial stages favoured range expansions of P. strobiformis , thus promoting gene flow.
Location  Mexico and the United States.
Methods  Estimates of genetic diversity and structure were obtained using chloroplast microsatellite loci of 23 populations of P. strobiformis across its entire range, seven neighbouring populations of Pinus ayacahuite Ehrenb. ex. Schtdl, and one population of Pinus flexilis James.
Results  The genetic diversity of P. strobiformis ( H _e = 0.856) was found to be high, especially in western populations, whereas eastern populations were less variable and more genetically similar to P. ayacahuite of central Mexico. We found evidence of significant phylogeographic structure ( N _ST = 0.444; P  =   0.026), high genetic structure ( R _ST = 0.270), and isolation by distance. Pairwise R _ST and samova (spatial analysis of molecular variance) results indicated an east–west partition of genetic variation, with populations within each group showing little differentiation and no isolation by distance.
Main conclusions  The phylogeographic structure of P. strobiformis across the entire range was pronounced, with two main genetic and geographic groups separated by the Chihuahuan Desert. However, within each of the two groups there was little population differentiation and no isolation by distance, suggesting genetic connectivity as a result of population expansions within these areas during glacial stages.     

Ancestry and divergence of subtropical montane forest isolates: molecular biogeography of the genus Abies (Pinaceae) in southern México and Guatemala

The genus Abies has a complex history in southern México and Guatemala. In this region, four closely related species, Abies flinckii , A. guatemalensis , A. hickelii , and A. religiosa , are distributed in fragmented and isolated montane populations. Range-wide genetic variation was investigated across species using cytoplasmic DNA markers with contrasted inheritance. Variation at two maternally inherited mitochondrial DNA markers was low. All species shared two of the nine mitotypes detected, while the remaining seven mitochondrial DNA types were restricted to a few isolated stands. Mitochondrial genetic differentiation across taxa was high ( G _ST = 0.933), it was not related to the taxonomic identity ( amova ; P  > 0.05) of the populations, and it was not phylogeographically structured ( G _ST ≈  N _ST). In contrast, variation at three paternally inherited chloroplast DNA microsatellites was high. Chloroplast genetic differentiation was lower ( G _ST = 0.402; R _ST = 0.547) than for mitochondrial DNA, but it was significantly related to taxonomy ( amova ; P  < 0.001), and exhibited a significant phylogeographical structure ( G _ST <  R _ST). Different analyses of population structure indicated that A. flinckii was the most divergent taxon, while the remaining three species formed a relatively homogeneous group. However, a small number of the populations of these three taxa, all located at the limits of their respective ranges or in the Transverse Volcanic Belt, diverged from this main cluster. These trends suggest that the Mesoamerican Abies share a recent common ancestor and that their divergence and speciation is mainly driven by genetic drift and isolation during the warm interglacial periods.     

The population genetic effects of ancestry and admixture in a subdivided cattle breed

The genetic structure of the Dexter, a minority cattle breed with complex demographic history, was investigated using microsatellite markers and a range of statistical approaches designed to detect both admixture and genetic drift. Modern representatives of two putative ancestral populations, the Devon and Kerry, together with the different populations of the Dexter, which have experienced different demographic histories, were analysed. Breed units showed comparatively high levels of genetic variability ( H _E = 0.63–0.68); however, distinct genetic subgroups were detected within the Dexter, which could be attributed to known demographic events. Much lower diversity was identified in three small, isolated Dexter populations ( H _E = 0.52–0.55) and higher differentiation ( F _ST > 0.13) was found. For one of these populations, where strong selection has taken place, we also found evidence of a demographic bottleneck. Three methods for quantifying breed admixture were applied and substantial method-based variation in estimates for the genetic contribution of the two proposed ancestral populations for each subdivision of the Dexter was found. Results were consistent only in the case of a group consisting of selected Traditional Dexter animals, where the ancestor of the modern Kerry breed was also determined as the greater parental contributor to the Dexter. The inconsistency of estimation of admixture proportions between the methods highlights the potentially confounding role of genetic drift in shaping small population structure, and the consequences of accurately describing population histories from contemporary genetic data.     

Genetic structure and population dynamics of a heteroecious plant pathogen Melampsora larici-epitea in short-rotation coppice willow plantations

Complex life strategies are common among plant pathogens belonging to rust fungi ( Uredinales ). The heteroecious willow rust Melampsora larici-epitea produces five spore stages and alternates on larch ( Larix ). To shed light on the epidemiology of this pathogen, amplified fragment length polymorphisms (AFLPs) were used to determine the genetic diversity and genetic structure of rust samples collected from coppice willow ( Salix ) plantations at three UK sites (LA, CA and MC) over three sampling dates (September 2000, July 2001 and September 2001). Of the total of 819 isolates, 465 were unique AFLP phenotypes and there was a shift in genotype diversity between the two seasons (0.67 in 2000 and 0.87–0.89 in 2001). No phenotypes were common between the two seasons within a site, suggesting that the rust did not overwinter as an asexual stage within plantations. A temporal analysis detected large amounts of genetic drift ( F _S = 0.15–0.26) between the two seasons and very small effective population sizes ( N _e  =  2–3) within sites. These results all point to a new colonization of the plantations by the rust in the second season (2001). The F _ST-analogue values were Φ_CT = 0.121, Weir and Cockerham's θ = 0.086 and the Bayesian estimate θ^B = 0.087–0.096. The results suggest that the sources of inoculum were somewhat localized and the same sources were mainly responsible for disease epidemics in LA and CA over the two seasons. The relatively low F _ST-values among sites (0.055–0.13) suggest the existence of significant gene flow among the three sampled sites.     

Potential refugium on the Qinghai–Tibet Plateau revealed by the chloroplast DNA phylogeography of the alpine species Metagentiana striata (Gentianaceae)

Metagentiana striata is an alpine annual herbaceous plant endemic to the east of the Qinghai–Tibet (Q–T) Plateau and adjacent areas. The phylogeography of M. striata was studied by sequencing the chloroplast DNA (cpDNA) trn S– trn G intergenic spacer. Ten haplotypes were identified from an investigation of 232 individuals of M. striata from 14 populations covering the entire geographical range of this species. The level of differentiation amongst populations was very high ( G _ST = 0.746; N _ST = 0.774) and a significant phylogeographical structure was observed ( P  < 0.05). An analysis of molecular variance found a high variation amongst populations (76%), with F _ST = 0.762 (highly significant, P  < 0.001), indicating that little gene flow occurred amongst the different regions; this was explained by the isolation of populations by high mountains along the Q–T Plateau and adjacent areas ( N _m = 0.156). Only one ancestral haplotype (A) was common and widespread throughout the distributional range of M. striata. The populations of the Hengduan Mountains region of the south-eastern Q–T Plateau showed high diversity and uniqueness of haplotypes. It is suggested that this region was the potential refugium of M. striata during the Quaternary glaciation, and that interglacial and postglacial range expansion occurred from this refugium. This scenario was in good agreement with the results of nested clade analysis, which inferred that the current spatial distribution of cpDNA haplotypes and populations resulted from range expansion, together with past allopatric fragmentation events.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 125–140.     

Genetic structure and differentiation of Gentiana atuntsiensis W. W. Smith and G. striolata T. N. Ho (Gentianaceae) as revealed by ISSR markers

The Hengduan Mountains are the core region of the Himalaya hotspot, and are renowned for their high levels of endemism. Gentiana atuntsiensis and G. striolata are two closely related and morphologically similar species endemic to this region. In this study, inter-simple sequence repeat (ISSR) markers were used to investigate the genetic structure within these two species, as well as the differentiation between them. An analysis of molecular variance-derived estimate demonstrated only 13.5% of genetic differentiation between the two species. Considering their adjacent distribution patterns, low genetic divergence, and clear clustering into two groups, it is hypothesized that the two species arose from a rapid and recent speciation event induced mainly by geographical isolation. A relatively high level of genetic diversity was revealed in each species (Shannon's index of diversity: H _sp = 0.324 and 0.391; H _pop = 0.225 and 0.274; for G. atuntsiensis and G. striolata , respectively). Most of the genetic variation was partitioned within populations ( Ø _ST = 0.232 and 0.226 in G. atuntsiensis and G. striolata , respectively). The large population sizes, outcrossing breeding system, and small, light seeds that disperse widely may explain the genetic structure in both species.  © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 225–232.     

Comparative genetic analyses of historical and contemporary collections highlight contrasting demographic histories for the bumble bees Bombus pensylvanicus and B. impatiens in Illinois

Direct comparison of genetic patterns between museum specimens and contemporary collections can be a powerful approach for detecting recent demographic changes. Using microsatellite markers, we examined historical and contemporary genetic variation from an apparently declining bumble bee species, Bombus pensylvanicus , and from a stable species, Bombus impatiens , in central Illinois. For each species, we genotyped specimens from the Illinois Natural History Survey collected from three populations between 1969–1972 and from a resurvey of the same areas conducted in 2008. Population structure in B . pensylvanicus increased markedly over the last four decades (from θ_ST = 0.001 to 0.027) while no structure was detected in B . impatiens for either time period (θ_ST = –0.006 to –0.003). Changes in genetic diversity were not significant for either species, although small reductions were observed for B . pensylvanicus in all three populations. Coalescent simulations incorporating both contemporary and historical samples suggest that this small change is not surprising for recent population declines, as large reductions in genetic diversity were only apparent under the most severe bottleneck scenarios. These results demonstrate how comparisons of genetic patterns between temporal periods and species can help elucidate potential threats to population health and suggest several strategies that might be useful in the conservation of B . pensylvanicus in the Midwestern USA.     

Conservation genetics of Amorpha georgiana (Fabaceae), an endangered legume of the Southeastern United States

Amorpha georgiana (Fabaceae) is an endangered legume species found in longleaf pine savannas in the Southeastern United States. Approximately 900 individuals and 14 populations remain, most of which are concentrated in North Carolina. Eleven microsatellite loci were used to explore genetic diversity, population structure and recent population bottlenecks using genotypic data from 132 individuals collected at ten different localities. Although A. georgiana is quite rare, it exhibited high levels of genetic diversity (17.7 alleles/locus; H _o = 0.65, H _E = 0.75). Most of the genetic variation was found within rather than between populations of this species. The single remaining Georgia population was well differentiated from populations of the Carolinas ( F _ST > 0.1), which had weaker structure among them ( F _ST < 0.1). Only a geographically disjunct population showed strong evidence of a recent population bottleneck, perhaps due to a recent founder event. Hybridization with A. herbacea was also detected. For conservation management plans, A. georgiana populations in each geographic region (North Carolina, South Carolina and Georgia) plus a disjunct population in North Carolina (Holly Shelter) should be treated as separate management units for which in situ conservation, including habitat restoration and use of prescribed burns, should ensure persistence of this species and preservation of its evolutionary potential.     

Comparison of quantitative and molecular genetic variation of native vs. invasive populations of purple loosestrife (Lythrum salicaria L., Lythraceae)

Study of adaptive evolutionary changes in populations of invasive species can be advanced through the joint application of quantitative and population genetic methods. Using purple loosestrife as a model system, we investigated the relative roles of natural selection, genetic drift and gene flow in the invasive process by contrasting phenotypical and neutral genetic differentiation among native European and invasive North American populations ( Q _ST −  F _ST analysis). Our results indicate that invasive and native populations harbour comparable levels of amplified fragment length polymorphism variation, a pattern consistent with multiple independent introductions from a diverse European gene pool. However, it was observed that the genetic variation reduced during subsequent invasion, perhaps by founder effects and genetic drift. Comparison of genetically based quantitative trait differentiation ( Q _ST) with its expectation under neutrality ( F _ST) revealed no evidence of disruptive selection ( Q _ST >  F _ST) or stabilizing selection ( Q _ST <  F _ST). One exception was found for only one trait (the number of stems) showing significant sign of stabilizing selection across all populations. This suggests that there are difficulties in distinguishing the effects of nonadaptive population processes and natural selection. Multiple introductions of purple loosestrife may have created a genetic mixture from diverse source populations and increased population genetic diversity, but its link to the adaptive differentiation of invasive North American populations needs further research.     

Population genetic structure of the tiger prawn (Penaeus monodon) in the coastal waters of South China, based on mitochondrial DNA control region sequences

Genetic variation and population structure of Penaeus monodon in the coastal waters of South China were detected using mitochondrial DNA control region sequences. Eighty individuals were collected at Sanya, Shenzhen, Zhanjiang and Beihai; 69 haplotypes with 157 polymorphic sites were detected. Nucleotide diversity (π) of the combined samples (6.16 ± 3.01%) was much higher than many other species in Chinese seas, such as Penaeus japonicus , Portunus trituberculatus , and Acanthopagrus schlegeli . Genetic differentiation was significant between Beihai and Sanya (pairwise F _ST = 0.09836, P < 0.05), and between Beihai and Shenzhen (pairwise F _ST = 0.12153, P < 0.05). Significant genetic differentiation among all populations was found by analysis of molecular variance ( amova ) ( F _ST = 0.053, P = 0.037 < 0.05). The upgma dendrogram of the four populations showed Sanya and Shenzhen as the closest to each other, with Beihai having the greatest genetic distance from Sanya and Shenzhen. The tiger prawn of the coastal waters of South China should therefore be bred as two separated stocks, avoiding inbreeding or outbreeding selection of P. monodon in the captive breeding program. According to our results one source population is Beihai, and the others are from Sanya and Shenzhen.     

Population genetics of a marine bivalve, Pinctada maxima, throughout the Indo-Australian Archipelago shows differentiation and decreased diversity at range limits

Intraspecific genetic diversity governs the potential of species to prevail in the face of environmental or ecological challenges; therefore, its protection is critical. The Indo-Australian Archipelago (IAA) is a significant reservoir of the world's marine biodiversity and a region of high conservation priority. Yet, despite indications that the IAA may harbour greater intraspecific variation, multiple-locus genetic diversity data are limited. We investigated microsatellite DNA variation in Pinctada maxima populations from the IAA to elucidate potential factors influencing levels of genetic diversity in the region. Results indicate that genetic diversity decreases as the geographical distance away from central Indonesia increases, and that populations located towards the centre of P. maxima 's range are more genetically diverse than those located peripherally ( P <  0.01). Significant partitioning of genetic variation was identified ( F _ST = 0.027; R _ST = 0.023, P  < 0.001) and indicates that historical biogeographical episodes or oceanographic factors have shaped present population genetic structure. We propose that the genetic diversity peak in P. maxima populations may be due to (i) an abundance of suitable habitat within the IAA, meaning larger, more temporally stable populations can be maintained and are less likely to encounter genetic bottlenecks; and/or (ii) the close proximity of biogeographical barriers around central Indonesia results in increased genetic diversity in the region because of admixture of genetically divergent populations. We encourage further genetic diversity studies of IAA marine biota to confirm whether this region has a significant role in maintaining intraspecific diversity, which will greatly assist the planning and efficacy of future conservation efforts.     

Conservation genetics of Hebe speciosa (Plantaginaceae) an endangered New Zealand shrub

All extant populations of Hebe speciosa (Plantaginaceae), a threatened endemic New Zealand shrub, were investigated using the amplified fragment length polymorphism technique (AFLP). Genetic diversity indices varied significantly among geographical regions and were positively correlated with population size. Among-population genetic differentiation was high (mean pairwise Φ_ST = 0.47), implying complex historical relationships between disjunct populations and negligible contemporary gene flow. Southern populations exhibited extremely low genetic diversity relative to those found in Northland, suggesting that these populations may be more recent in origin. Patterns of genetic relationship among some populations indicate pre-European Māori dispersal and cultivation. The three northernmost populations were found to contain the majority of the species' remaining genetic diversity and thus, should be a focus for future conservation management. Some southern sites may also be culturally significant as evidence of Māori trade and cultivation of Hebe speciosa .  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 149 , 229–239.     

Genetics of the peripheral populations of the alpine bullhead, Cottus poecilopus (Scorpaeniformes, Cottidae) in Poland

The alpine bullhead ( Cottus poecilopus ) in Poland is highly polymorphic ( P for examined populations in the range of 0.0–0.45, mean P  = 0.11, P for species 0.64) in seven out of 11 loci studied ( Pgd-1, Mdh-1, Ck-1, Gpd-1, Gpd-2, Gpi-1, Gpi-2 ). However, they reveal very low heterozygosity (mean H _o = 0.007, mean H _e = 0.019), which may result from population subdivisions, small genetically effective size ( N _e) of some populations and frequent inbreeding, the latter being probably mediated through polygyny. The index of genetic differentiation ( G _ST) for the Polish metapopulation equals 0.48, which is relatively high. By far, the strongest are genetic differences between the Sudeten-Carpathian group and the Hańcza population. Gene flow between the Sudeten-Carpathian group and the Hańcza population is very limited and their divergence may have started as early as the last (Eemian) interglacial period.     

Evidence for independent origin of two spring‐spawning ciscoes (Salmoniformes: Coregonidae) in Germany

Combined analyses of mitochondrial DNA (mtDNA) and microsatellite loci were performed to assess the genetic differentiation of two spring‐spawning ciscoes from each other and from sympatric Coregonus albula in two German lakes. Polymorphism was screened at six microsatellite loci and mtDNA for a total of 247 and 94 ciscoes, respectively. Microsatellite data showed a weak differentiation between spring‐spawning Coregonus fontanae and sympatric C. albula in Lake Stechlin ( F _ST = 0–0·008), whereas a significant differentiation was observed between spring‐spawning Coregonus lucinensis and sympatric C. albula in Lake Breiter Luzin ( F _ST = 0·013–0·039). A more pronounced genetic difference was observed between both spring‐spawning species ( F _ST = 0·05–0·128). Shared mtDNA haplotypes among sympatric species within both Lake Stechlin and Lake Breiter Luzin were observed, whereas no haplotype was shared between C. fontanae and C. lucinensis . These results suggest an independent origin for spring‐spawning ciscoes in each lake. Evidence is also provided for mtDNA introgression of Coregonus sardinella into C. lucinensis and C. albula in Lake Breiter Luzin. Postglacially, this species or at least a population which showed mtDNA introgression has colonized the Baltic Sea basin up to the glacial margin that was located between Lakes Stechlin and Breiter Luzin.     

Genetic population structure and dispersal in Atlantic Island caddisflies

SUMMARY 1. Population genetic structure of Wormaldia tagananana, a caddis with a narrow geographic range and endemic to the Canary Islands, was investigated by studying allozyme variation at 11 putative loci in five of the eight extant populations on Tenerife and La Gomera. Genetic variability, population structure and gene flow were compared with those reported previously in more widespread Trichoptera, particularly Canarian populations of the non-endemic limnephilid Mesophylax aspersus, to examine the hypothesis that the Wormaldia , with its restricted range, would exhibit relatively little genetic variability and gene flow.
2. Despite it being a narrow-range island endemic, genetic variability in populations of W. tagananana is broadly similar to values reported for more widespread caddis.
3. Significant genetic population structure was observed in W. tagananana (overall F _ST = 0.387), greater than that seen in M. aspersus and amongst the highest reported for lotic caddis to date. Several site- and island-specific alleles were reported, providing further evidence for the relative isolation of individual Wormaldia populations.
4. Significant deviations from Hardy–Weinberg equilibrium were found in four of five populations (overall F _IS = 0.675). This could result from within-locality population substructuring, or offspring within a reach being the product of a limited number of matings.
5. This genetic evidence supports the hypothesis that the restricted range of W. tagananana is, at least in part, because of limited dispersal ability.     

Contrasting levels of genetic diversity between the common, self-compatible Liparis kumokiri and rare, self-incompatible Liparis makinoana (Orchidaceae) in South Korea

Levels of allozyme variation and intrapopulation spatial genetic structure of the two terrestrial clonal orchids Liparis kumokiri , a self-compatible relatively common species, and L. makinoana , a self-incompatible rare species, were examined for 17 ( N  = 1875) and four ( N  = 425) populations, respectively, in South Korea. Populations of L. makinoana harboured high levels of genetic variation ( H _e = 0.319) across 15 loci. In contrast, L. kumokiri exhibited a complete lack of allozyme variation ( H _e = 0.000). Considering the lack of genetic variability, it is suggested that current populations of L. kumokiri in South Korea originated from a genetically depauperate ancestral population. For L. makinoana , a significant deficit of heterozygosity (mean F _IS = 0.198) was found in population samples excluding clonal ramets, suggesting that pollen dispersal is localized, generating biparental inbreeding. The significant fine-scale genetic structuring (≤ 2 m) found in a previous study, in addition to the moderate levels of population differentiation ( F _ST = 0.107) and the significant relationship between genetic and geographical distances ( r  = 0.680) found here, suggests a leptokurtic distribution of seed dispersal for L. makinoana . Although populations of L. makinoana harbour high levels of genetic variation, they are affected by a recent genetic bottleneck. This information suggests that genetic drift and limited gene flow could be the main evolutionary forces for speciation of a species-rich genus such as Liparis .  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 41–48.