Local Genetic Differentiation Research Articles

Genetic diversity and population structure of the mangrove lime (Merope angulata) in India revealed by AFLP and ISSR markers

The mangrove lime, Merope angulata (Willd.) Swingle (Rutaceae) is a threatened mangrove associate species occurring sporadically in the tidal forests from Papua New Guinea to the east coast of India. It is an underutilized salt tolerant plant related to Citrus. We have applied AFLP and ISSR markers to estimate the extent of genetic diversity among 55 individuals of M. angulata, sampled from two natural populations (Bhitarkanika Wildlife Sanctuary) and one ex situ population (Jharkhali Mangrove Ecological Garden) in India. A combined analysis of both AFLP and ISSR markers revealed low polymorphism (42.93%) and a moderate heterozygosity and Shannon diversity index (H=0.393, I=0.571) in the species. The Jaccard genetic distance among 55 accessions ranged from 0.16 to 0.74 (average 0.43). Analysis of population genetic structure using Bayesian method in STRUCTURE software identified two genetic clusters. FST statistics and AMOVA results indicated low population differentiation with high gene flow. Haplotype indices and mismatch distributions indicated some evidence of expansion in the two natural populations. Outcrossing test revealed a predominantly out-breeding system with high outcrossing rate. The high gene flow detected among the populations indicates that M. angulata does not face any genetic drift, and hence no local genetic differentiation and population divergence. The highly fragmented state of its habitats warrants adequate measures for maintenance of genetic diversity in this species without further depletion. This is the first report on molecular analysis of genetic diversity and population structure of M. angulata from its native distributional range in India.

Do founder size, genetic diversity and structure influence rates of expansion of North American grey squirrels in Europe?

AbstractAimThis study investigates how founder size may affect local genetic diversity and spatial genetic structure of the invasive American eastern grey squirrel (Sciurus carolinensis) in European areas. It also examines whether dispersal propensity and invasion rate may be related to founder size, genetic diversity and structure.LocationPiedmont, Italy; Northern Ireland, Northumberland and East Anglia, UK.MethodsAcross the invaded range in Europe, 315 squirrels from 14 locations, grouped in four areas, were sampled and examined at 12 highly polymorphic microsatellite loci. We estimated both genetic variation and population structure using AMOVA, Mantel tests and Bayesian analysis. We also estimated migration rates and range expansion rates.ResultsGenetic diversity varied in accordance with numbers of founders across populations. For instance, the Italian population had the smallest founder size and lowest genetic variability, whereas Northumberland had high values for both. Significant levels of genetic differentiation were observed in all the examined regions. Gene flow, migration and population range expansion rate were also higher in England and Ireland than in Italy.Main conclusionsPopulations descending from human‐mediated releases of few individuals were more genetically depauperate and more differentiated than populations established from a greater number of founders. Propagule pressure is therefore a significant factor in squirrel invasions. There is a trend whereby larger founder sizes were associated with greater genetic diversity, more dispersal, less local genetic differentiation and faster range expansion rate in squirrels. These findings have important management implications for controlling spread rate of squirrels and other invasive species: good practice should prioritize preventing further releases and the merging of genetically distinct populations as these events can augment genetic diversity.

Relative contributions of neutral and non-neutral genetic differentiation to inform conservation of steelhead trout across highly variable landscapes.

Mounting evidence of climatic effects on riverine environments and adaptive responses of fishes have elicited growing conservation concerns. Measures to rectify population declines include assessment of local extinction risk, population ecology, viability, and genetic differentiation. While conservation planning has been largely informed by neutral genetic structure, there has been a dearth of critical information regarding the role of non-neutral or functional genetic variation. We evaluated genetic variation among steelhead trout of the Columbia River Basin, which supports diverse populations distributed among dynamic landscapes. We categorized 188 SNP loci as either putatively neutral or candidates for divergent selection (non-neutral) using a multitest association approach. Neutral variation distinguished lineages and defined broad-scale population structure consistent with previous studies, but fine-scale resolution was also detected at levels not previously observed. Within distinct coastal and inland lineages, we identified nine and 22 candidate loci commonly associated with precipitation or temperature variables and putatively under divergent selection. Observed patterns of non-neutral variation suggest overall climate is likely to shape local adaptation (e.g., potential rapid evolution) of steelhead trout in the Columbia River region. Broad geographic patterns of neutral and non-neutral variation demonstrated here can be used to accommodate priorities for regional management and inform long-term conservation of this species.

NONSTATIONARY PATTERNS OF ISOLATION‐BY‐DISTANCE: INFERRING MEASURES OF LOCAL GENETIC DIFFERENTIATION WITH BAYESIAN KRIGING

Patterns of isolation-by-distance (IBD) arise when population differentiation increases with increasing geographic distances. Patterns of IBD are usually caused by local spatial dispersal, which explains why differences of allele frequencies between populations accumulate with distance. However, spatial variations of demographic parameters such as migration rate or population density can generate nonstationary patterns of IBD where the rate at which genetic differentiation accumulates varies across space. To characterize nonstationary patterns of IBD, we infer local genetic differentiation based on Bayesian kriging. Local genetic differentiation for a sampled population is defined as the average genetic differentiation between the sampled population and fictive neighboring populations. To avoid defining populations in advance, the method can also be applied at the scale of individuals making it relevant for landscape genetics. Inference of local genetic differentiation relies on a matrix of pairwise similarity or dissimilarity between populations or individuals such as matrices of FST between pairs of populations. Simulation studies show that maps of local genetic differentiation can reveal barriers to gene flow but also other patterns such as continuous variations of gene flow across habitat. The potential of the method is illustrated with two datasets: single nucleotide polymorphisms from human Swedish populations and dominant markers for alpine plant species.

Population genetics and phylogenetic relationships of beetles (Coleoptera: Histeridae and Staphylinidae) from the Sonoran Desert associated with rotting columnar cacti

Dozens of arthropod species are known to feed and breed in the necrotic tissues (rots) of columnar cacti in the Sonoran Desert. Because the necrotic patches are ephemeral, the associated arthropods must continually disperse to new cacti and therefore the populations of any given species are expected to show very little local genetic differentiation. While this has been found to be true for the cactophilic Drosophila, the evolutionary histories and characteristics of other arthropods inhabiting the same necrotic patches, especially the beetles, have yet to be examined. Here we used nucleotide sequence data from segments of the mitochondrial 16S rRNA and cytochrome c oxidase subunit I (COI) genes to examine population structure and demographic history of three sympatric beetle species (Coleoptera: Histeridae and Staphylinidae) collected on senita cactus (Lophocereus schottii) from six widely-separated localities on the Baja California peninsula of northwestern Mexico. Two histerids, Iliotona beyeri and Carcinops gilensis, and an unidentified staphylinid, Belonuchus sp., showed little or no population structure over a broad geographic area on the peninsula, consistent with the prediction that these beetles should show high dispersal ability. Demographic tests revealed varying levels of historical population expansion among the beetle species analyzed, which are discussed in light of their ecologies and concurrent biogeographic events. Additionally, phylogenetic analyses of COI sequences in Carcinops collected on a variety of columnar cacti from both peninsular and mainland Mexico localities revealed several species-level partitions, including a putative undescribed peninsular species that occurred sympatrically with C. gilensis on senita.

Unravelling genetics at the top: mountain islands or isolated belts?

In mountain plant populations, local adaptation has been described as one of the main responses to climate warming, allowing plants to persist under stressful conditions. This is especially the case for marginal populations at their lowest elevation, as they are highly vulnerable. Adequate levels of genetic diversity are required for selection to take place, while high levels of altitudinal gene flow are seen as a major limiting factor potentially precluding local adaptation processes. Thus, a compromise between genetic diversity and gene flow seems necessary to guarantee persistence under oncoming conditions. It is therefore critical to determine if gene flow occurs preferentially between mountains at similar altitudinal belts, promoting local adaptation at the lowest populations, or conversely along altitude within each mountain. Microsatellite markers were used to unravel genetic diversity and population structure, inbreeding and gene flow of populations at two nearby altitudinal gradients of Silene ciliata, a Mediterranean high-mountain cushion plant. Genetic diversity and inbreeding coefficients were similar in all populations. Substantial gene flow was found both along altitudinal gradients and horizontally within each elevation belt, although greater values were obtained along altitudinal gradients. Gene flow may be responsible for the homogeneous levels of genetic diversity found among populations. Bayesian cluster analyses also suggested that shifts along altitudinal gradients are the most plausible scenario. Past population shifts associated with glaciations and interglacial periods in temperate mountains may partially explain current distributions of genetic diversity and population structure. In spite of the predominance of gene flow along the altitudinal gradients, local genetic differentiation of one of the lower populations together with the detection of one outlier locus might support the existence of different selection forces at low altitudes.

Ice bridging as a dispersal mechanism for Arctic terrestrial vertebrates and the possible consequences of reduced sea ice cover

The dispersal abilities of terrestrial mammals are severely constrained by water crossings, resulting in islands generally supporting less diverse mammal faunas than similar continental areas. In ice-affected Arctic regions, seasonal or permanent ice cover provides a bridging mechanism for dispersal, allowing water gaps to be crossed more rapidly and with less energy cost than is entailed in swimming. Consequently, islands that might be out of reach if waters were open become much more readily colonised in the presence of ice. We reviewed the distribution of terrestrial mammals on selected islands throughout the Arctic and analyse historical data for several sites in the Canadian Arctic where mammal populations have undergone extirpation and re-colonisation. We use these data to assess the value of ice for the dispersal of Arctic terrestrial mammals. Given observed dispersal distances we estimate the likely impact of future ice reduction on island faunas. We predict that, as ice cover duration shortens, immigration will decline leading to increased extinctions of island populations and potentially, in the long-term, local genetic differentiation. The eventual disappearance of ice bridges, preventing the immigration of southern species, may leave certain arctic archipelagos as the last refuge for typical Arctic mammals.

Testing hypotheses for morphological differences among populations of Miconia sellowiana (Melastomataceae) in southern Brazil

Micona sellowiana in different types of vegetation (Grassland, Montane Atlantic forest, Upper Montane Atlantic forest and Araucaria Pine forest). Although such variability could be due to phenotypic plasticity, an alternative explanation for this phenomenon is the existence of genetic differentiation among populations resulting from genetic drift or adaptation to different environments. The goal of the present study was to investigate the extent of genetic structures among populations of Miconia sellowiana using a neutral dominant genetic marker (RAPD - Random Amplification of Polymorphic DNA). There was considerable variability in the studied samples, resulting in 96.5% polymorphic loci and a Gst = 0.13. The analysis of molecular variance showed the populations are genetically structured (p < 0.001). The subpopulations of M. sellowiana were grouped similarly together using genetic (based on a neutral marker) or morphological dendrograms, suggesting that the morphological differences observed are the result of local genetic differentiation by genetic drift and not the alleged phenotypic plasticity of the species

Geographical Variation in Egg Mass and Egg Content in a Passerine Bird

Reproductive, phenotypic and life-history traits in many animal and plant taxa show geographic variation, indicating spatial variation in selection regimes. Maternal deposition to avian eggs, such as hormones, antibodies and antioxidants, critically affect development of the offspring, with long-lasting effects on the phenotype and fitness. Little is however known about large-scale geographical patterns of variation in maternal deposition to eggs. We studied geographical variation in egg components of a passerine bird, the pied flycatcher (Ficedula hypoleuca), by collecting samples from 16 populations and measuring egg and yolk mass, albumen lysozyme activity, yolk immunoglobulins, yolk androgens and yolk total carotenoids. We found significant variation among populations in most egg components, but ca. 90% of the variation was among individuals within populations. Population however explained 40% of the variation in carotenoid levels. In contrast to our hypothesis, we found geographical trends only in carotenoids, but not in any of the other egg components. Our results thus suggest high within-population variation and leave little scope for local adaptation and genetic differentiation in deposition of different egg components. The role of these maternally-derived resources in evolutionary change should be further investigated.

Strong spatial genetic structure in five tropical Piper species: should the Baker–Fedorov hypothesis be revived for tropical shrubs?

Fifty years ago, Baker and Fedorov proposed that the high species diversity of tropical forests could arise from the combined effects of inbreeding and genetic drift leading to population differentiation and eventually to sympatric speciation. Decades of research, however have failed to support the Baker–Fedorov hypothesis (BFH), and it has now been discarded in favor of a paradigm where most trees are self-incompatible or strongly outcrossing, and where long-distance pollen dispersal prevents population drift. Here, we propose that several hyper-diverse genera of tropical herbs and shrubs, including Piper (>1,000 species), may provide an exception. Species in this genus often have aggregated, high-density populations with self-compatible breeding systems; characteristics which the BFH would predict lead to high local genetic differentiation. We test this prediction for five Piper species on Barro Colorado Island, Panama, using Amplified Fragment Length Polymorphism (AFLP) markers. All species showed strong genetic structure at both fine- and large-spatial scales. Over short distances (200–750 m) populations showed significant genetic differentiation (Fst 0.11–0.46, P < 0.05), with values of spatial genetic structure that exceed those reported for other tropical tree species (Sp = 0.03–0.136). This genetic structure probably results from the combined effects of limited seed and pollen dispersal, clonal spread, and selfing. These processes are likely to have facilitated the diversification of populations in response to local natural selection or genetic drift and may explain the remarkable diversity of this rich genus.

Genetic Risk Assessment of a Threatened Remnant Population of Hairy Prairie-Clover (Dalea villosa var. villosa) in the Canadian Prairie

Hairy prairie-clover [Dalea villosa (Nutt.) Spreng. var. villosa] is a threatened Canadian wildflower. To facilitate the efforts of conserving this threatened plant, amplified fragment length polymorphism (AFLP) technique was applied to assess genetic diversity in a remnant hairy prairie-clover population in the Canadian Prairie. Three AFLP primer pairs were employed to genotype 610 individual plants from the population and 15 plants from a North Dakota composite population, and 100 polymorphic AFLP bands were analyzed. The assayed plants displayed 23% AFLP variation present between the remnant population and the North Dakota composite population, but maintained a high level (91%) of AFLP variation within patches of the remnant population. The individual genetic distinctiveness measured by average AFLP dissimilarity was positively associated with latitude and negatively with elevation. The among-patch AFLP variation was significantly related to inter-patch distance, indicating local genetic differentiation within the remnant population. However, the proportions of within-patch AFLP variation were not associated with any patch characteristics assessed (i.e., patch size, perimeter, nearest neighbor distance, mean inter-patch distance). No fine-scale genetic structure was found within three large patches, suggesting little genetic correlations present for plants five meters apart. Some genetically distinctive and diverse patches were also identified. These findings indicate that the genetic risk of the remnant hairy prairie-clover population in the Canadian Prairie is low.

Patterns of connectivity in Citril Finches Serinus citrinella: sympatric wintering of allopatric breeding birds?

Capsule Individuals ringed at different localities, where previous analyses detected local genetic and morphological differentiation, overlapped in wintering areas. Aims To analyse winter site fidelity and connectivity in Citril Finches, a species with locally differentiated allopatric breeding populations, but which forms into pairs at the end of the wintering period, when these populations could be sympatric. Methods Analysis based on 238 recoveries obtained from 12 648 birds ringed at alpine localities and 2368 birds ringed at lower-elevation wintering areas in Central Catalonia. Results Citril Finches showed marked winter site fidelity. Birds ringed at different sub-alpine mountain ranges tended to winter in different river basins, but we found some overlap between these sub-populations. Birds from different localities within the same mountain range partly overlapped in wintering areas. Conclusion We found that many Citril Finch sub-populations cohabit during the winter pair formation period, which prompts the question of how Citril Finch populations can maintain local differentiation despite the ample opportunities for gene flow.

Fine-scale genetic structure suggests low levels of short-range gene flow in a wolf population of the Italian Apennines

We investigated local gene flow in a high-density wolf (Canis lupus) population of the Italian Apennines, where no effective barrier to wolf dispersal was present. From 1998 to 2004 we examined wolf carcasses and non-invasively collected samples, focusing on three mountain districts, separated by two valleys, where wolf packs showed high spatial stability. Using nine autosomal microsatellites we successfully genotyped 177 samples, achieving the identification of 74 wolves. Genetic relatedness steeply decreased with increasing distance between sampling areas, thus suggesting that short-distance interpack migration is infrequent in this population. In addition, no individual from a central pack under intensive monitoring was sampled in the range of the surrounding packs over a 4-year period. The limited short-distance gene flow resulted in a cryptic genetic structure, which was revealed by Bayesian analysis. A different genetic cluster was found in each of the three mountain areas, and a small proportion of first-generation immigrants was detected. Overall, the present study suggests that local genetic differentiation in Italian wolves might arise from high spatial stability of packs and can be favoured by a combination of long-range dispersal, the attitude to mate between unrelated individuals and a high young mortality rate.

Variation in phenotypic characters of pale flax (Linum bienne Mill.) from Turkey

The diversity of pale flax (Linum bienne Mill.) as the progenitor of cultivated flax (L. usitatissimum L.) has not been well documented and the domestication syndromes in cultivated flax are poorly understood. An attempt was made to characterize 34 pale flax accessions and six cultivated flax accessions collected during 2007 summer in Turkey. A total of 12 quantitative and 7 qualitative characters covering vegetative and generative plant parts, including phenological traits, were assessed. The occurrence of yellow anthers well known in cultivated flax is reported for the first time in pale flax. Pale flax displayed larger variation in vegetative plant parts and growth habit than the cultivated flax and more heterogeneity within accessions. Within pale flax, a higher degree of variation was observed in many generative parts such as the flower characters than in the capsule and seed characters. Based on the assayed characters, the pale flax from Turkey was grouped into three clusters and these clusters were associated with site elevation and longitude, further confirming local genetic differentiation in pale flax from Turkey. These findings are significant for further studies of flax domestication history and useful for further exploitation of wild flax in genetic improvement of cultivated flax.

Geographic Genetic Differentiation of a Malaria Parasite, Plasmodium mexicanum, and Its Lizard Host, Sceloporus occidentalis

Gene flow, and resulting degree of genetic differentiation among populations, will shape geographic genetic patterns and possibly local adaptation of parasites and their hosts. Some studies of Plasmodium falciparum in humans show substantial differentiation of the parasite in locations separated by only a few kilometers, a paradoxical finding for a parasite in a large, mobile host. We examined genetic differentiation of the malaria parasite Plasmodium mexicanum, and its lizard host, Sceloporus occidentalis, at 8 sites in northern California, with the use of variable microsatellite markers for both species. These lizards are small and highly territorial, so we expected local genetic differentiation of both parasite and lizard. Populations of P. mexicanum were found to be differentiated by analysis of 5 markers (F(st) values >0.05-0.10) over distances as short as 230-400 m, and greatly differentiated (F(st) values >0.25) for sites separated by approximately 10 km. In contrast, the lizard host had no, or very low, levels of differentiation for 3 markers, even for sites >40 km distant. Thus, gene flow for the lizard was great, but despite the mobility of the vertebrate host, the parasite was locally genetically distinct. This discrepancy could result if infected lizards move little, but their noninfected relatives were more mobile. Previous studies on the virulence of P. mexicanum for fence lizards support this hypothesis. However, changing prevalence of the parasite, without changes in density of the lizard, could also result in this pattern.

Pre-zygotic factors best explain reproductive isolation between the hybridizing species of brittle-stars Acrocnida brachiata and A. spatulispina (Echinodermata: Ophiuroidea)

The two brittle-stars Acrocnida brachiata (Montagu 1804) and A. spatulispina (Stöhr and Muths in J Mar Biol Assoc, 2009) exhibit strong spatial segregation along the coast of Brittany (France), the first being subtidally distributed relative to the other intertidal species. Despite a very high degree of mitochondrial DNA divergence, previous preliminary results hinted at the potential for hybridization to occur. Therefore, we specifically aim to determine local levels of hybridization between these two species and to investigate the relative roles of pre- and post- zygotic isolation processes acting to decrease local hybridization patterns. Mitochondrial DNA, allozymes and the Internal Transcribed Spacer 2 region of the ribosomal DNA were all used on 529 brittle-stars sampled locally in June and September 2005, among six stations in Douarnenez Bay, a site situated at the tip of Brittany. Only 2.6% of all samples analyzed were identified as potential hybrids. However, these were twice more frequent in June, just after the reproductive period, than in September after selective mortality acted to reduce the proportions of hybrids. In addition to the abrupt bathymetric segregation between the two species, spawning asynchrony also clearly restricts hybridization to low levels, which shows the importance of pre-zygotic mechanisms in maintaining reproductive isolation. Moreover, both limited hybridization events and adult mortalities following reproduction tend to generate local genetic differentiation at the intra-species level. On the contrary, the genetic structure is homogenized by migration of juveniles or adults and hybrids mortalities over the summer period.

Spatial and temporal changes in genetic structure of greenhouse and field populations of cabbage looper,Trichoplusia ni

Trichoplusia ni is a subtropical moth that migrates annually from southern California to southern British Columbia, Canada where it invades vegetable greenhouses and field crops. The heated greenhouse environment has altered the natural extinction-recolonization dynamics of T. ni populations, and allows year-round persistence in some locations. In addition, the extensive use of the biopesticide, Bacillus thuringiensis subspecies kurstaki (Bt) in some greenhouses has selected for resistance. Here we investigated the genetic structure of T. ni populations in British Columbia greenhouses and in field populations in California and British Columbia using amplified fragment length polymorphisms (AFLP) as related to patterns of Bt resistance. The majority of British Columbia field populations were similar to the California field populations, the potential source of migrants. However populations in two geographic areas with high concentrations of greenhouses showed local genetic differentiation. Some of these populations experienced severe bottlenecks over-winter and following Bt sprays. Greenhouse populations showed a pattern of isolation by distance and a strong positive relationship between genetic differentiation and levels of Bt resistance. These patterns indicate that greenhouses that sometimes support year-round populations of T. ni and the ensuing strong bottlenecking effects following winter cleanups and Bt application cause genetic differentiation of T. ni populations. Long distance migrants to field populations contribute to genetic homogeneity of these.

Contrasting genetic structures of two parasitic nematodes, determined on the basis of neutral microsatellite markers and selected anthelmintic resistance markers

For the first time, the neutral genetic relatedness of natural populations of Trichostrongylid nematodes was investigated in relation to polymorphism of the beta-tubulin gene, which is selected for anthelminthic treatments. The aim of the study was to assess the contribution of several evolutionary processes: migration and genetic drift by neutral genetic markers and selection by anthelminthic treatments on the presence of resistance alleles at beta-tubulin. We studied two nematode species (Teladorsagia circumcincta and Haemonchus contortus) common in temperate climatic zones; these species are characterized by contrasting life history traits. We studied 10 isolated populations of goat nematode parasites: no infected adult goat had been exchanged after the herds were established. Beta-tubulin polymorphism was similar in these two species. One and two beta-tubulin alleles from T. circumcincta and H. contortus respectively were shared by several populations. Most of the beta-tubulin alleles were 'private' alleles. No recombination between alleles was detected in BZ-resistant alleles from T. circumcincta and H. contortus. The T. circumcincta populations have not diverged much since their isolation (F(ST) <0.08), whereas H. contortus displayed marked local genetic differentiation (F(ST) ranging from 0.08 to 0.18). These findings suggest that there are severe bottlenecks in the H. contortus populations, possibly because of their reduced abundance during unfavourable periods and their high reproductive rate, which allows the species to persist even after severe population reduction. Overall, the data reported contradict the hypothesis of the origin of beta-tubulin resistance alleles in these populations from a single mutational event, but two other hypotheses (recurrent mutation generating new alleles in isolated populations and the introduction of existing alleles) emerge as equally likely.

Multi‐annual density fluctuations and habitat size enhance genetic variability in two northern voles

In order to gain a better understanding of the consequences of population density cycles and landscape structure for the genetic composition in time and space of vole populations, we analyzed the multiannual genetic structure of the two numerically dominant, sympatric small rodent species of northernmost Fennoscandia. Red volesMyodes rutilusand grey‐sided volesM. rufocanuswere trapped in the subarctic birch forest along three fjords over five years. Along each fjord, there were four or five altitudinal transects each with five trapping stations. Spring and fall population densities were estimated from mark–recapture data. Grey‐sided voles exhibited higher amplitude density fluctuations than red voles. Polymorphism at eight or nine microsatellite loci, determined in 1228 voles, was used to estimate local genetic diversity and differentiation among samples. Genetic diversity was higher in grey‐sided voles than in red voles. Spring densities had no effect on local genetic diversity or on differentiation. The amplitude of density fluctuations and the extent of favorable habitat (sub‐arctic birch forest) surrounding each site had a positive effect on genetic diversity, and the amplitude of density fluctuations had a negative effect on differentiation in red voles, for which fluctuating populations were compared with more stable populations. The harmonic mean of densities, reflecting average population sizes, had a negative effect on genetic diversity in red voles, but a positive effect in grey‐sided voles, for which only fluctuating populations were compared. No other effects were significant for grey‐sided voles. A temporal assignment test showed that the spatial structure was more stable in time for populations with more stable population dynamics. Altogether our results suggest that high amplitude density fluctuations lead to more gene flow and higher genetic diversity in vole populations.

The genetic status of the violet copperLycaena helle– a relict of the cold past in times of global warming

Rising temperatures and agricultural changes (intensification and succession on fallow land) during the last few decades have caused a strong decline of moist and cool sites on nutrient‐poor grasslands and species depending on these habitats. We tested the effects of habitat deterioration on a local and regional scale in such a species, the highly endangered butterflyLycaena helle, which was more widely distributed over central Europe during the postglacial period, but has recently become restricted to some remnants. We analysed five polymorphic microsatellite loci in 220 individuals sampled at ten different localities. The study sites in Germany, Luxembourg and Belgium are geographically split into three mountain regions: the Ardennes, the Eifel and the Westerwald; the latter is separated from the other two by the river Rhine. A comparatively high genetic diversity was detected in all local populations and genetic differentiation was found among the Ardennes, the Eifel and the Westerwald (FCT: 0.084). The genetic differentiation among all populations (FST: 0.137) underlines natural and anthropogenic habitat fragmentation. While ongoing gene flow seems to exist among the Eifel populations indicating the only intact metapopulation, a high genetic differentiation in the Ardennes and the Westerwald indicates a disruption of population connectivity. Our genetic data obtained on different spatial scales show the genetic consequence of long‐term isolation and should trigger necessary conservation measures at the metapopulation level.