Soil seed bank contributes significantly to genetic variation of Hypericum sinaicum in a changing environment

The contribution of soil seed bank of a desert endemic plant species in maintaining genetic diversity has been addressed in this paper through investigating the differences in genetic diversity and structure (using AFLP markers) between plants grown from soil seed bank and standing crop plants within and among five populations of H. sinaicum growing at St. Katherine Protectorate, southern Sinai, Egypt. Standard genetic diversity measures showed that the molecular variation within and among populations was highly significantly different between standing crop and soil seed bank. While soil seed bank had lower genetic diversity than standing crop populations, pooling soil seed bank with standing crop samples resulted in higher diversity. The results revealed also that soil seed bank had lower differentiation (7 %) than among populations of the standing crop (18 %). Results of neighbor-joining, Bayesian clustering and principal coordinate analysis showed that soil seed banks had a separate gene pool different from standing crop. The study came to the conclusion that the genetic variation of the soil seed bank contributes significantly to the genetic variation of the species. This also stresses the importance of elucidating the genetic diversity and structure of the soil seed bank for any sound and long-term conservation efforts for desert species. These have been growing in small-size populations for a long time that any estimates gained only from aboveground sampling of populations may be ambiguous.     

Comparison of genetic variation in populations of wild rice, Oryza rufipogon, plants and their soil seed banks

Wild rice, Oryza rufipogon, has endangered species conservation status and it is subject to in situ conservation in China. To understand the potential of the seed bank in species conservation and population restoration, this study compared the genetic diversity of O. rufipogon plants with that of its soil seed banks in two marshes. A total of 11 pairs of rice SSR primers were used and 9 were polymorphic. Allele frequencies of the seeds differed significantly from those of surface plants and varied between soil layers. Relatively more alleles and higher genetic diversity (H _e) were found in plant populations, relative to seed banks. The numbers of germinable seeds and the level of genetic variation in seed banks decreased with the increasing of soil depth, indicating a rapid seed loss. Genetic differentiation was detected between sites and between plant and seed populations, as well as among seeds of different soil strata. Rapid seed loss, partly dormancy loss, and nonrandom seed mortality are discussed as the possible contributors to the pattern of reduced genetic variation within seed banks, compared to plants. These could also be responsible for the considerable genetic differentiation between populations. The seed population held about 72% of the total genetic variation of O. rufipogon in each marsh, indicating the potential of seed banks for restoring population variabilities if the plant populations were lost.     

Impact of river dynamics on the genetic variation of Gypsophila repens (Caryophyllaceae): a comparison of heath forest and more dynamic gravel bank populations along an alpine river

• Alpine rivers are, despite anthropogenic water flow regulation, still often highly dynamic ecosystems. Plant species occurring along these rivers are subject to ecological disturbance, mainly caused by seasonal flooding. Gypsophila repens typically grows at higher altitudes in the Alps, but also occurs at lower altitudes on gravel banks directly along the river and in heath forests at larger distances from the river. Populations on gravel banks are considered non‐permanent and it is assumed that new individuals originate from seed periodically washed down from higher altitudes. Populations in heath forests are, in contrast, permanent and not regularly provided with seeds from higher altitudes through flooding. If the genetic structure of this plant species is strongly affected by gene flow via seed dispersal, then higher levels of genetic diversity in populations but less differentiation among populations on gravel banks than in heath forests can be expected.
• In this study, we analysed genetic diversity within and differentiation among 15 populations of G. repens from gravel banks and heath forests along the alpine River Isar using amplified fragment length polymorphisms (AFLP).
• Genetic diversity was, as assumed, slightly higher in gravel bank than in heath forest populations, but genetic differentiation was, in contrast to our expectations, comparable among populations in both habitat types.
• Our study provides evidence for increased genetic diversity under conditions of higher ecological disturbance and increased seed dispersal on gravel banks. Similar levels of genetic differentiation among populations in both habitat types can be attributed to the species' long lifetime, a permanent soil seed bank and gene flow by pollinators among different habitats/locations.

     

Can a seed bank provide demographic and genetic rescue in a declining population of the endangered shrub <Emphasis Type="Italic">Acacia pinguifolia</Emphasis>?

Many threatened species suffer reduced genetic diversity as a result of small population size and isolation. However, species with a persistent seed bank may be buffered against genetic loss as seed banks are expected to accumulate the reproductive output of many seasons. For fire-dependent species in decline, prescribed ecological burning may be a means to stimulate germination and recover genetic diversity stored in the seed bank, providing a demographic and genetic rescue effect. Here we investigated the effectiveness of this strategy in a small, isolated and inbred population of the endangered shrub, Acacia pinguifolia. We surveyed genetic diversity and structure of remnant populations of A. pinguifolia and monitored regeneration before and after burning. Germination was stimulated by fire, but seedling numbers 18 months post-fire were low and barely above the number of adults killed by the fire. Genetic diversity was marginally higher in the post-fire seedling cohort than the pre-fire adults (H_E = 0.1 vs. 0.09, respectively). Outcrossing rates of open-pollinated seed from surrounding plants suggested moderately high levels of self-fertilisation (t _m  = 0.65) and analysis of fine-scale genetic structure implied pollen and seed dispersal over distances of several metres, suggesting that restricted gene flow and inbreeding may act to limit genetic diversity in the seed bank. We conclude that prescribed burning has not been immediately successful as a recovery strategy for this relictual population of A. pinguifolia, though future monitoring may detect additional recruits. Alternative conservation strategies, including performing inter-population crosses, may be required to restore genetic diversity and ameliorate extinction risks.     

人工与自然恢复条件下地被层优势种大羽藓的遗传多样性比较

基于随机扩增多态性DNA(RAPD)方法比较了川西米亚罗地区3个人工云杉林样地和3个天然次生林样地大羽藓(Thuidium cym bifolium)种群的遗传多样性及分化程度。人工林种群的平均多态位点百分比(PPL)为12.7%,Ne i’s基因多样性(HE)为0.042,Shannon’s信息指数(S)为0.064,种群内遗传一致度(I)为0.952;天然次生林种群则依次为10.0%、0.027、0.043和0.960。人工林种群和天然次生林种群Gst分别为0.592和0.702,Fst分别为0.639和0.695;结合UPGMA聚类和PCA分析,发现种群间的基因交流极少。单因素方差分析显示,人工林下大羽藓种群的遗传多样性水平显著高于天然次生林下种群(p<0.05),表明在皆伐迹地上通过人工造林能有效地促进林下物种遗传多样性的恢复。     

广东高州7个普通野生稻居群遗传结构的SSR分析

利用32对SSR引物对来自全部7个自然居群的217份广东高州普通野生稻(简称“高野”)材料进行遗传结构、多样性和遗传聚类分析。结果表明, 高野各居群因遗传结构存在差异而相对独立, 但各居群之间由于存在基因渗透又具有一定的相似性。高野总体多样性指数(Ht)为0.65, 居群内的多样性(HS=0.431)略大于居群间的多样性(DS=0.392), 二者差异并不显著。居群间的遗传分化系数(GST)为0.611, 说明高野群体的遗传差异是由居群内和居群间的遗传分化共同作用的结果。其中A、B、E居群间, D、F、G居群间遗传相似性较高, C居群与其它居群之间存在较大差异。根据7个居群的遗传结构, 结合其地理分布状况, 认为遗传多样性最大的B和E居群以及遗传分化最小的C居群应作为重点对象进行保护。     

Genetic structure of continental and island populations of the Mediterranean endemic Cyclamen balearicum (Primulaceae)

Cyclamen balearicum is a self-compatible perennial herb endemic to the western Mediterranean Basin. This species occurs in five geographically isolated terrestrial islands in southern France and on four Balearic islands. In this study, we compare genetic variability and differentiation within and among 11 terrestrial island populations and 17 true island populations. Of nine readable enzyme loci, five were polymorphic in both terrestrial and true islands. F statistics showed a significant heterozygote deficiency in all populations, probably due to high levels of autonomous selfing, restricted gene flow, and subsequent genetic drift. Genetic diversity was higher in terrestrial islands than on the Balearic islands, suggesting that the Balearic islands were colonized when they were in contact with the continent. Population differentiation was greater among terrestrial islands (Fst = 0.417 and Gst = 0.344) than among true islands (Fst = 0.112 and Gst = 0.093). Furthermore, differentiation among populations on the Basses Cévennes terrestrial island was greater (Fst = 0.254) than among populations on the true island of Mallorca (Fst = 0.163). The greater genetic differentiation among terrestrial islands could have been caused by genetic bottlenecks associated with changes in climate and human land use that may have reduced population sizes more severely in terrestrial islands in southern France than on the Balearic islands.     

Genetic diversity in Hemileia vastatrix based on RAPD markers

Random amplified polymorphic DNA (RAPD) was used to assess the genetic structure of Hemileia vastatrix populations. Forty-five rust isolates with different virulence spectra and from different hosts and geographical regions were analyzed. Out of 45 bands, generated with three RAPD primers, 35 (78%) were polymorphic and scored as molecular markers. Cluster analysis exhibits unstructured variability of this pathogen with regard to physiological race, geographical origin or host. The genotypic diversity (H') inferred from Shannon's index was higher than gene diversity (Ht), suggesting that diversity is distributed among clonal lineages. Estimates of gene diversity in Africa and Asia populations were higher in total (Ht) as compared to within population diversity (Hs). Genetic differentiation was considerable among coffee rust isolates from Africa (Gst = 0.865) and Asia (Gst = 0.768) but not among isolates from South America (Gst = 0.266). We concluded that genetic diversity in H. vastatrix was moderately low and that the genetic differentiation among populations shows that asexual reproduction is likely to play an important role in the population biology of this fungus. This should be taken into account for the development of breeding programs.     

Temporal patterns of genetic variation across a 9-year-old aerial seed bank of the shrub Banksia hookeriana (Proteaceae)

The pattern of accumulation of genetic variation over time in seed banks is poorly understood. We examined the genetic structure of the aerial seed bank of Banksia hookeriana within a single 15-year-old population in fire-prone southwestern Australia, and compared genetic variation between adults and each year of a 9-year-old seed bank using amplified fragment length polymorphism (AFLP). B. hookeriana is well suited to the study of seed bank dynamics due to the canopy storage of its seeds, and because each annual crop can be identified. A total of 304 seeds from nine crop years and five maternal plants were genotyped, along with 113 plants from the adult population. Genetic variation, as assessed by the proportion of polymorphic markers (P(p)) and Shannon's index (I), increased slightly within the seed bank over time, while gene diversity (H(j)), did not change. P(p), I, and H(j) all indicated that genetic variation within the seed bank quickly approached the maximal level detected. Analysis of molecular variance revealed that less than 4% of variation could be accounted for by variation among seeds produced in different years, whereas there was greater differentiation among maternal plants (12.7%), and among individual seeds produced by different maternal plants (83.4%). With increasing population age, offspring generated each year were slightly more outbred, as indicated by an increase in the mean number of nonmaternal markers per offspring. There were no significant differences for H(j) or I between adults and the seed bank. Viability of seeds decreased with age, such that the viability of 9-year-old seeds was half that of 2-year-old seeds. These results suggest that variable fire frequencies have only limited potential to influence the amount of genetic variation stored within the seed bank of B. hookeriana.     

Low genetic diversity and high genetic differentiation in the critically endangered Omphalogramma souliei (Primulaceae):implications for its conservation

Omphalogramma souliei Franch. Is an endangered perennial herb only distributed in alpine areas of SW China. ISSR markers were applied to determine the genetic variation and genetic structure of 60 individuals of three populations of O. Souliei in NW Yunnan, China. The genetic diversity at the species level is low with P= 42.5% (percentage of polymorphic bands) and Hsp=0.1762 (total genetic diversity). However, a high level of genetic differentiation among populations was detected based on different measures (Nei's genetic diversity analysis: Gst=0.6038; AMOVA analysis: Fst=0.6797). Low level of genetic diversity within populations and significant genetic differentiation among populations might be due to the mixed mating system in which xenog-amy predominated and autogamy played an assistant role in O. Souliei. The genetic drift due to small population size and limited current gene flow also resulted in significant genetic differentiation. The assessment of genetic variation and differentiation of the endangered species provides important information for conservation on a genetic basis. Conservation strategies for this rare endemic species are proposed.     

Microsatellite diversity and genetic structure of fragmented populations of the rare,fire-dependent shrub Grevillea macleayana

Recent habitat loss and fragmentation superimposed upon ancient patterns of population subdivision are likely to have produced low levels of neutral genetic diversity and marked genetic structure in many plant species. The genetic effects of habitat fragmentation may be most pronounced in species that form small populations, are fully self-compatible and have limited seed dispersal. However, long-lived seed banks, mobile pollinators and long adult lifespans may prevent or delay the accumulation of genetic effects. We studied a rare Australian shrub species, Grevillea macleayana (Proteaceae), that occurs in many small populations, is self-compatible and has restricted seed dispersal. However, it has a relatively long adult lifespan (c. 30 years), a long-lived seed bank that germinates after fire and is pollinated by birds that are numerous and highly mobile. These latter characteristics raise the possibility that populations in the past may have been effectively large and genetically homogeneous. Using six microsatellites, we found that G. macleayana may have relatively low within-population diversity (3.2-4.2 alleles/locus; Hexp = 0.420-0.530), significant population differentiation and moderate genetic structure (FST = 0.218) showing isolation by distance, consistent with historically low gene flow. The frequency distribution of allele sizes suggest that this geographical differentiation is being driven by mutation. We found a lack mutation-drift equilibrium in some populations that is indicative of population bottlenecks. Combined with evidence for large spatiotemporal variation of selfing rates, this suggests that fluctuating population sizes characterize the demography in this species, promoting genetic drift. We argue that natural patterns of pollen and seed dispersal, coupled with the patchy, fire-shaped distribution, may have restricted long-distance gene flow in the past.     

草鱼野生与选育群体线粒体DNA控制区D-loop遗传变异分析

为探究经过2个选育世代后选育群体遗传多样性和遗传结构的变化, 研究对4个野生群体(邗江、九江、石首和吴江)和2个选育世代(F1和F2)进行了线粒体DNA控制区(D-loop)序列的遗传变异分析。实验结果表明, 4个野生群体在单倍型数目(H)、单倍型多样性(H_d)、核苷酸多样性(π)、平均核苷酸差异数(K)水平上均高于2个选育世代, 在2个选育世代内表现为F1代群体的核苷酸多样性(π)和平均核苷酸差异数(K)大于F2代群体, 但单倍型多样性(H_d)小于F2代群体; 单倍型分析结果表明, 6个群体间无共享单倍型, 4个野生群体间共发现2种共享单倍型(Hap1和Hap3), 石首群体和2个选育世代共享1种单倍型(Hap15); 遗传分化指数(F_st)分析结果表明, 邗江、九江、吴江3个野生群体和2个选育世代间存在较大的遗传分化(F_st范围为0.41475—0.55128), 石首群体与F1代群体之间存在较小的遗传分化, 与F2代群体之间存在中等水平的遗传分化, 同时F1代群体与F2代群体之间存在较小的遗传分化; 基于6个群体276个个体构建的邻接(Neighbor-Joining, NJ)进化树和基于27种单倍型构建的单倍型网络图也得到了相似的结论, 即邗江、九江、吴江3个野生群体和2个选育世代间的亲缘关系较远, 石首群体和2个选育世代两两之间的亲缘关系较近。以上结果表明, 经过2个世代的选择育种, 选育群体的遗传结构已发生了变化, 并且随着选育的进行, 选育世代的遗传多样性下降的较为明显, 这警示着我们在今后的育种工作中应适当改变现有的选育方案, 并实时监测选育群体的遗传多样性, 以便为今后进一步的选育工作打下坚实的基础。     

云南西花蓟马rDNA-ITS2遗传多态性及其种群扩张

应用rDNA-ITS2基因序列对云南各地理种群西花蓟马Frankliniella occidentalis(Pergande)的遗传结构和遗传分化程度进行初步研究。经过比对112条序列,共发现了59个变异位点,定义了30种单倍型。云南省西花蓟马的单倍型多态性较高(Hd=0.90219),而核酸多态性较低(Pi=0.00891)。各地理种群西花蓟马的遗传分化指数Fst为0.00810,基因流Nm为30.61,表明各地理种群间遗传分化程度非常低,种群间存在充分的基因交流。对群体进行中性检验、错配分析表明西花蓟马群体曾经历过近期的种群扩张。分子方差分析(AMOVA)表明,云南西花蓟马的遗传变异主要来自于种群内部,种群间的遗传变异水平还非常低。从分子生物学的角度上也证实了西花蓟马近期入侵云南的事实。     

基于线粒体COI基因的中国西南地区木领针蓟马地理种群的遗传分化分析

【目的】木领针蓟马Helionothrips mube近年来成为芋头Colocasia esculenta上的一种常见害虫。本研究旨在探讨其中国西南地区地理种群间的遗传变异。【方法】通过Sanger法测定了21个地理种群132头木领针蓟马的线粒体COI基因序列,利用MEGA, DnaSP, Arlequin和Network等软件对木领针蓟马种群间的遗传多样性、遗传分化、分子变异等进行分析。【结果】获得的木领针蓟马132条线粒体COI序列(643 bp)中共发现34个变异位点、16种单倍型,其中单倍型H1出现频率最高、分布最广。木领针蓟马总群体的遗传多样性较高(Hd=0.712, Pi=0.00413, K=2.655),遗传分化程度极大(Fst=0.3443),基因交流水平不高(Nm=0.96)。分子方差分析(AMOVA)表明,木领针蓟马的遗传分化主要来自种群内部,Mantel检测出种群地理距离与遗传距离呈正相关。总群体中性检验Tajima’s D值显著负值,Fu’s Fs值不显著,错配分布曲线呈多峰。综合种群间遗传距离、单倍型系统发育树及中介网络图结果,表明四川成都(CHD)、云南昌宁(CHN)和贵州遵义(ZY)3个种群的遗传分化程度均高于其他种群。【结论】中国西南地区木领针蓟马总群体的遗传多样性较高,遗传分化明显,种群间的基因交流受到地理距离的影响,总群体在较近的历史时期内没有出现扩张现象。     

Can a seed bank maintain the genetic variation in the above ground plant population?

There are indications that a persistent seed bank can protect small and isolated plant populations from local extinction. Genetic mechanisms contributing to this phenomenon are the increase of local effective population size – and hence the decrease of genetic drift – through a reservoir of persistent seeds, and the accumulation of intergenerational genetic diversity in the seed bank. To find evidence for these mechanisms, we conducted two formal meta-analyses. First, we analyzed 42 published habitat fragmentation studies and investigated whether the degree of genetic differentiation between fragmented plant populations was mediated by seed longevity. Second, we reviewed 13 published studies reporting the genetic diversity of both the seed bank and the above ground plants, aiming at comparing genetic diversity contained in the seed bank with the above ground vegetation. We conclude that a persistent seed bank may indeed mitigate the consequences of habitat fragmentation and protect a species from genetic drift and population genetic differentiation. We found no evidence, however, of high levels of genetic diversity accumulating in the soil seed bank. If genetic differences are present between the standing crop and the seed bank, they are very likely the result of local selection acting either directly or indirectly as a filter on the alleles present in the seed bank. We finally suggest that 1) the role of the seed bank should not be neglected in habitat fragmentation studies and 2) it is not very fruitful to continue comparing seed bank genetic diversity with above ground plant genetic diversity, unless this is performed under different selection regimes.     

Can Soil Seed Banks Serve as Genetic Memory? A Study of Three Species with Contrasting Life History Strategies

We attempted to confirm that seed banks can be viewed as an important genetic reservoir by testing the hypothesis that standing (aboveground) plants represent a nonrandom sample of the seed bank. We sampled multilocus allozyme genotypes from three species with different life history strategies: Amaranthus retroflexus, Carduus acanthoides, Pastinaca sativa. In four populations of each species we analysed the extent to which allele and genotype frequencies vary in consecutive life history stages including the summer seed bank, which has been overlooked up to now. We compared the winter seed bank (i.e., seeds collected before the spring germination peak), seedlings, rosettes, the summer seed bank (i.e., seeds collected after the spring germination peak) and fruiting plants. We found that: (1) All three species partitioned most of their genetic diversity within life history stages and less among stages within populations and among populations. (2) All genetic diversity parameters, except for allele frequencies, were similar among all life history stages across all populations in different species. (3) There were differences in allele frequencies among life history stages at all localities in Amaranthus retroflexus and at three localities in both Carduus acanthoides and Pastinaca sativa. (4) Allele frequencies did not differ between the winter and summer seed bank in most Carduus acanthoides and Pastinaca sativa populations, but there was a marked difference in Amaranthus retroflexus. In conclusion, we have shown that the summer seed bank is not genetically depleted by spring germination and that a majority of genetic diversity remains in the soil through summer. We suggest that seed banks in the species investigated play an important role by maintaining genetic diversity sufficient for recovery rather than by accumulating new genetic diversity at each locality.     

No loss of genetic diversity in small and isolated populations of Medicago sativa subsp. falcata

Molecular allozyme markers of three polymorphic isozymes were used to estimate the genetic diversity among the seed progeny in fragmented Estonian populations of sickle medic Medicago sativa ssp. falcata L. depending on the population size and the isolation degree. Genetic diversity H_e was high in all populations, ranging between 0.795 and 0.893. No correlation between the genetic diversity measures and population size or isolation distance was found. Even the smallest population had equally high genetic diversity as about a hundred times larger population. Genetic differentiation of populations into two major groups was associated with the geographic position of populations, except one remote population. Elimination of seed progeny of reduced fitness by embryo abortion and continuous yearlong contribution of the highly heterozygous progeny through the soil seed bank are considered as important supplementary factors that have contributed to maintaining high levels of genetic diversity in populations of sickle medic in addition to its autotetraploid nature and perennial life form.     

Stratified analysis of the soil seed bank in the cedar glade endemic Astragalus bibullatus: evidence for historical changes in genetic structure

Persistent seed banks may provide information on historical changes in the genetic composition of populations. We used stratified sampling of the soil seed bank of Astragalus bibullatus (Pyne's ground plum) to assess levels of temporal variation in population genetic structure and to infer historical changes in the levels of inbreeding and relative gene flow. This species has an extremely limited distribution in the Central Basin of Tennessee, where it is found in open areas and along the edges of cedar glades. Protein electrophoresis was conducted on seedlings grown from seeds that had been recovered from three successive 1 cm thick layers of soil sampled from six sites. Analyses of seven polymorphic allozyme loci indicated that there were substantial levels of genetic differentiation among soil layers and sites. Higher levels of genetic diversity were found in seed than in vegetative populations that had been sampled in a previous study. Seed populations from the uppermost soil layer had higher heterozygote deficiencies, displayed higher levels of differentiation among sites, and had higher private allele frequencies than seed populations from the lower two layers. The change in heterozygosity and distribution of genetic variation among sites for the youngest soil layer is consistent with a pattern of increased selfing, sib mating, and decreased gene flow among populations. These changes in inbreeding and relative levels of gene flow are corroborated by information on historical land use practices in the region and support the hypothesis that loss of appropriate habitat has led to smaller population sizes and a more fragmented distribution of this cedar glade endemic.     

Evidence for ancient genetic subdivision among recently fragmented populations of the endangered shrub Grevillea caleyi (Proteaceae)

The genetic effects of population fragmentation cannot be interpreted without understanding the underlying pattern of genetic variation resulting from historic population processes. We used AFLP markers to determine genetic structure and distribution of genetic diversity among populations of an endangered Australian shrub Grevillea caleyi (Proteaceae). Populations that occurred historically on four ridges have new been fragmented to varying degrees, producing some large, relatively pristine populations and very small populations consisting of fewer than 10 adult plants. We found marked population genetic structure (65.9% of genetic variation was among populations) and a significant relationship between genetic and geographic distance (rm=0.564, P=0.004). However, only 14% of overall genetic differentiation was attributable to variation among ridges, compared with 52% among populations within ridges. Moreover, genetic diversity within samples of plants did not vary with either population size or degree of isolation. Thus, the present genetic structure of populations is probably almost entirely the product of historical events. Fine-scale structuring within populations prior to fragmentation may have been caused by limited seed and pollen dispersal, despite a complex suite of (mostly avian) pollinators, and a mixed mating system that allows a large amount of selfing. The combined effects of adult longevity and a soil-stored seed bank may have buffered the recently fragmented populations against the effects of dramatic reductions in numbers of adult plants.     

Genetic structure of the forest herb Primula elatior in a changing landscape

To investigate whether changes in land use and associated forest patch turnover affected genetic diversity and structure of the forest herb Primula elatior, historical data on landscape changes were combined with a population genetic analysis using dominant amplified fragment length polymorphism markers. Based on nine topographic maps, landscape history was reconstructed and forest patches were assigned to two age classes: young (less than 35 years) and old (more than 35 years). The level of differentiation among Primula populations in recently established patches was compared with the level of differentiation among populations in older patches. Genetic diversity was independent of population size (P > 0.05). Most genetic variation was present within populations. Within-population diversity levels tended to be higher for populations located in older forests compared with those for populations located in young forests (Hj = 0.297 and 0.285, respectively). Total gene diversity was also higher for old than for young populations (Ht = 0.2987 and 0.2828, respectively). The global fixation index FST averaged over loci was low, but significant. Populations in older patches were significantly more differentiated from each other than were populations in recently established patches and they showed significant isolation by distance. In contrast, no significant correlations between pairwise geographical distance and FST were found for populations in recently established patches. The location of young and old populations in the studied system and altered gene flow because of increased population density and decreased inter-patch distances between extant populations may explain the observed lower genetic differentiation in the younger populations. This study exemplifies the importance of incorporating data on historical landscape changes in population genetic research at the landscape scale.