Genetic differentiation of an endangered capercaillie (<Emphasis Type="Italic">Tetrao urogallus</Emphasis>) population at the Southern edge of the species range

The low-latitude limits of species ranges are thought to be particularly important as long-term stores of genetic diversity and hot spots for speciation. The Iberian Peninsula, one of the main glacial refugia in Europe, houses the southern distribution limits of a number of boreal species. The capercaillie is one such species with a range extending northwards to cover most of Europe from Iberia to Scandinavia and East to Siberia. The Cantabrian Range, in North Spain, constitutes the contemporary south-western distribution limit of the species. In contrast to all other populations, which live in pure or mixed coniferous forests, the Cantabrian population is unique in inhabiting pure deciduous forests. We have assessed the existence of genetic differentiation between this and other European populations using microsatellite and mitochondrial DNA (mtDNA) extracted from capercaillie feathers. Samples were collected between 2001 and 2004 across most of the current distribution of the Cantabrian population. Mitochondrial DNA analysis showed that the Cantabrian birds form a distinct clade with respect to all the other European populations analysed, including the Alps, Black Forest, Scandinavia and Russia, which are all members of a discrete clade. Microsatellite DNA from Cantabrian birds reveals the lowest genetic variation within the species in Europe. The existence of birds from both mtDNA clades in the Pyrenees and evidence from microsatellite frequencies for two different groups, points to the existence of a Pyrenean contact zone between European and Cantabrian type birds. The ecological and genetic differences of the Cantabrian capercaillies qualify them as an Evolutionarily Significant Unit and support the idea of the importance of the rear edge for speciation. Implications for capercaillie taxonomy and conservation are discussed.     

Genetic structure of the world's polar bear populations

We studied genetic structure in polar bear (Ursus maritimus) populations by typing a sample of 473 individuals spanning the species distribution at 16 highly variable microsatellite loci. No genetic discontinuities were found that would be consistent with evolutionarily significant periods of isolation between groups. Direct comparison of movement data and genetic data from the Canadian Arctic revealed a highly significant correlation. Genetic data generally supported existing population (management unit) designations, although there were two cases where genetic data failed to differentiate between pairs of populations previously resolved by movement data. A sharp contrast was found between the minimal genetic structure observed among populations surrounding the polar basin and the presence of several marked genetic discontinuities in the Canadian Arctic. The discontinuities in the Canadian Arctic caused the appearance of four genetic clusters of polar bear populations. These clusters vary in total estimated population size from 100 to over 10 000, and the smallest may merit a relatively conservative management strategy in consideration of its apparent isolation. We suggest that the observed pattern of genetic discontinuities has developed in response to differences in the seasonal distribution and pattern of sea ice habitat and the effects of these differences on the distribution and abundance of seals.     

Central Asian origin of and strong genetic differentiation among populations of the rare and disjunct Carex atrofusca (Cyperaceae) in the Alps

Aim Carex atrofusca has an arctic–alpine distribution in the Northern Hemisphere, with only a few, disjunct localities known in the European Alps. These alpine populations are declining in number and size. In contrast, C. atrofusca has a wide circumpolar distribution range and is abundant in large parts of the Arctic. The degree of genetic differentiation of the alpine populations and their importance for the conservation of the intraspecific genetic variation of the species is unknown. Location Eurasia and Greenland, with emphasis on the European Alps. Methods We applied amplified fragment length polymorphism (AFLP) fingerprinting and sequences of chloroplast DNA to determine the position of the alpine populations in a circumpolar phylogeography of C. atrofusca and to unravel the patterns of genetic diversity and differentiation within the Alps. Results Two distinct major groups were detected in a neighbour‐joining analysis of AFLP data and in parsimony analysis of chloroplast DNA sequences: one consisting of the populations from Siberia and Greenland and one consisting of all European populations as sister to the populations from Central Asia. Within Europe, the populations from the Tatra Mountains and those from Scotland and Scandinavia formed two well‐supported groups, whereas the alpine populations did not constitute a group of their own. The genetic variation in the Alps was almost completely partitioned among the populations, and the populations were almost invariable. Main conclusions The alpine populations possibly originated due to immigration from Central Asia. The strong differentiation among them suggests that genetic drift has been strongly acting on the populations, either as a consequence of founder events during colonization or due to subsequent reduction of population sizes during warm stages of the Holocene.     

Africa goes Europe: The complete phylogeography of the marbled white butterfly species complex Melanargia galathea/M. lachesis (Lepidoptera: Satyridae)

Climatic oscillations influence the distribution of species in time. Thermophilic species survived the ice ages in refugia around the Mediterranean. Northern Africa is one of the possibly important refugia. In this study we test the genetic differentiation between northern African and European populations, using the marbled white butterfly species complex, Melanargia galathea/M. lachesis, as a model. We studied 18 allozyme loci in 876 individuals from 23 populations representing a major part of Europe (northern Spain to Romania) and the western part of northern Africa (Atlas Mountains). The African populations resemble the European ones in allelic richness; their genetic diversity is higher than in Europe. Cluster analysis discriminated five European genetic groups: M. lachesis, a western European lineage, and three eastern European lineages. However, the African samples did not form a separate cluster within this phenogram, but clustered randomly within the Balkan/southeastern European groups. The genetic differentiation among the African populations (F_ST 8.8%) was higher than that within any of the European lineages (F_ST 2.6–5.5%). The high genetic diversity and the relatively strong differentiation of the four African populations sampled in a comparatively limited area of the Atlas Mountains indicate that the most probable origin of M. galathea is northern Africa, with its sibling species, M. lachesis, evolving in parallel in Iberia. Most probably, M. galathea colonised Europe first during the Eem interglacial, some 130 ky ago. Since M. lachesis must have existed on the Iberian peninsula during that period already, M. galathea should have reached Europe via Italy. The genetic differentiation to distinct groups in Europe most probably evolved during the following Würm glacial period.     

Colonization of vegetation-rich moraines and inference of multiple sources of colonization in the High Arctic for Salix arctica

Vegetation-rich patches in the High Arctic may serve as a significant source for vegetation reconstruction in the climate changes. Diversity and colonization, however, of such potential source populations in the High Arctic has rarely been studied. We examined chloroplast sequence variation in Salix arctica, a key species in the Canadian High Arctic, from four adjacent glacial moraines of differing ages on Ellesmere Island, Canada, as well as two other populations located at the center and southern end of the species’ range. The estimated ages of the moraines varied from 35,000 to 250 years old. The older moraine populations showed higher within-population genetic variation compared with the other moraine populations, which is generally attributed to differences in establishment age associated with plant densities among moraines. The moraines with smaller plant density had lower genetic diversity and had no private haplotypes, indicating the local population size and genetic diversity may not be recovered within a few thousand years. This suggests seed dispersal at a local scale may be limited even in species with high velocity of seed dispersal, and that High Arctic vegetation-rich patches may serve as significant source populations for sustaining local genetic diversity. In addition, the three regions we observed comprised an evolutionarily distinct lineage and significant population differentiation. This implies multiple sources for the colonization during the most recent deglaciation, resulting in the current wide distribution. Local as well as range-wide processes of colonization would be essential to understand vegetation responses in High Arctic to the environmental changes.     

Molecular phylogeography of Dryas integrifolia: glacial refugia and postglacial recolonization

Chloroplast DNA variation in the Arctic plant species Dryas integrifolia (Rosaceae) was analysed in relation to both the present-day geographical distribution of populations and to Pleistocene fossil records of this species. The phylogeographical structure was weak but the analysis of haplotype diversity revealed several groups of haplotypes having present-day geographical ranges that overlap locations postulated from geographical and fossil evidence to have been glacial refugia. Based on this information we infer that two important refugial sources of Arctic recolonization by this species were Beringia and the High Arctic. Two other putative refugia, located southeast of the ice sheet and along coastal regions of the eastern Arctic may have served as sources for recolonization of smaller portions of the Arctic. The genetic substructure in the species is mostly due to variation among populations regardless of the ecogeographical region in which they are found. Spatial autocorrelation at the regional scale was also detected. High levels of diversity both within populations and ecogeographical regions are probably indicative of population establishment from several sources possibly combined with recent gene flow.     

The wide but disjunct range of the European mountain plant Androsace lactea L. (Primulaceae) reflects Late Pleistocene range fragmentation and post‐glacial distributional stasis

Aim Our aim was to reconstruct the spatio‐temporal genetic diversification of Androsace lactea, a widely but disjunctly distributed European mountain plant, to test the hypothesis that its distribution is the result of vicariance, in the late Tertiary or during the Pleistocene, or alternatively of long‐distance dispersal. We also addressed the phylogeographic history of the Alps, emphasizing the role of Pleistocene refugia at their northern margin. Location The central and southern European mountain ranges. Methods We gathered amplified fragment length polymorphism (AFLP) data and plastid DNA sequences from one to four individuals of each of 26 populations spanning the entire distribution area. AFLP data were analysed with Bayesian clustering approaches, neighbour‐joining analysis and NeighbourNet. Plastid sequences were used to depict relationships among haplotypes in a statistical parsimony network, to test for population expansions, and to obtain age estimates in a Bayesian framework. Results The AFLP data suggested that many populations were genetically strongly differentiated. The internal structure, however, was weak, and only two major groups of populations, from the north‐western Alps and adjacent regions and from the easternmost Alps, were supported in the neighbour‐joining analysis. One of the Bayesian clustering approaches differentiated three groups of populations: Northern Alps, easternmost Alps and the remaining distribution area. Eleven closely related plastid haplotypes were found, separated by maximally four mutational steps, resulting in a star‐like parsimony network. None of several estimators suggested statistically significant population expansions. The diversification age was inferred to be (mean/median) 0.135/0.08 Ma (95% highest posterior density interval 0.364–0.006 Ma). Main conclusions We found no evidence that long‐distance dispersal shaped the disjunct distribution range; our data rather favoured a vicariance scenario. However, in contrast to the hypothesis that wide but disjunct distributions are old, we conclude that range fragmentation probably happened in the Late Pleistocene, perhaps during the last glaciation. In the Alps, most populations are at least close to formerly unglaciated areas. Our data support distributional stasis and suggest that important refugia were situated at the north‐eastern, but also at the northern and north‐western edges of the Alps, thereby strengthening the evidence for glacial refugia in this strongly glaciated region.     

Evolutionary history of the European whitefish Coregonus lavaretus (L.) species complex as inferred from mtDNA phylogeography and gill-raker numbers

We compared mitochondrial DNA and gill-raker number variation in populations of the European whitefish Coregonus lavaretus (L.) species complex to illuminate their evolutionary history, and discuss mechanisms behind diversification. Using single-strand conformation polymorphism (SSCP) and sequencing 528 bp of combined parts of the cytochrome oxidase b (cyt b) and NADH dehydrogenase subunit 3 (ND3) mithochondrial DNA (mtDNA) regions, we documented phylogeographic relationships among populations and phylogeny of mtDNA haplotypes. Demographic events behind geographical distribution of haplotypes were inferred using nested clade analysis (NCA) and mismatch distribution. Concordance between operational taxonomical groups, based on gill-raker numbers, and mtDNA patterns was tested. Three major mtDNA clades were resolved in Europe: a North European clade from northwest Russia to Denmark, a Siberian clade from the Arctic Sea to southwest Norway, and a South European clade from Denmark to the European Alps, reflecting occupation in different glacial refugia. Demographic events inferred from NCA were isolation by distance, range expansion, and fragmentation. Mismatch analysis suggested that clades which colonized Fennoscandia and the Alps expanded in population size 24 500-5800 years before present, with minute female effective population sizes, implying small founder populations during colonization. Gill-raker counts did not commensurate with hierarchical mtDNA clades, and poorly with haplotypes, suggesting recent origin of gill-raker variation. Whitefish designations based on gill-raker numbers were not associated with ancient clades. Lack of congruence in morphology and evolutionary lineages implies that the taxonomy of this species complex should be reconsidered.     

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

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

Phylogeography of Scots pine in Europe and Asia based on mtDNA polymorphisms

We analyzed mitochondrial DNA polymorphisms to search for evidence of the genetic structure and patterns of admixture in 124 populations (N = 1407 trees) across the distribution of Scots pine in Europe and Asia. The markers revealed only a weak population structure in Central and Eastern Europe and suggested postglacial expansion to middle and northern latitudes from multiple sources. Major mitotype variants include the remnants of Scots pine at the north-western extreme of the distribution in the Scottish Highlands; two main variants (western and central European) that contributed to the contemporary populations in Norway and Sweden; the central-eastern European variant present in the Balkan region, Finland, and Russian Karelia; and a separate one common to most eastern European parts of Russia and western Siberia. We also observe signatures of a distinct refugium located in the northern parts of the Black Sea basin that contributed to the patterns of genetic variation observed in several populations in the Balkans, Ukraine, and western Russia. Some common haplotypes of putative ancient origin were shared among distant populations from Europe and Asia, including the most southern refugial stands that did not participate in postglacial recolonization of northern latitudes. The study indicates different genetic lineages of the species in Europe and provides a set of genetic markers for its finer-scale population history and divergence inference.     

Three times out of Asia Minor: the phylogeography of Arabis alpina L. (Brassicaceae)

Arabis alpina is a characteristic plant in arctic-alpine habitats and serves as a classical example to demonstrate biology, ecology and biogeography of arctic-alpine disjuncts. It has a wider distribution than most other arctic-alpine plants, covering all European mountain systems, the Canary Islands, North Africa, the high mountains of East Africa and Ethiopia, the Arabian Peninsula and mountain ranges of Central Asia in Iran and Iraq. Additionally it is found in the northern amphi-Atlantic area including northeastern North America, Greenland, Iceland, Svalbard and northwestern Europe. We used markers from the nuclear (internal transcribed spacer of ribosomal DNA) and chloroplast genome (trnL-F region) to reconstruct its phylogeographic history. Both markers revealed clear phylogeographic structure. We suggest that A. alpina originated in Asia Minor less than 2 million years ago based on synonymous mutation rates of different genes (plastidic matK, nuclear adh and chs). From the Asian ancestral stock one group migrated via the Arabian Peninsula to the East African high mountains. A second group gave rise to all European and northern populations, and also served as source for the northwest African populations. A third group, which is still centred in Asia, migrated independently southwards and came into secondary contact with the East African lineage in Ethiopia, resulting in high genetic diversity in this area. In the Mediterranean regions, the genetic diversity was relatively high with numerous unique haplotypes, but almost without geographic structure. In contrast, the populations in the northern amphi-Atlantic area were extremely depauperate, suggesting very recent (postglacial) expansion into this vast area from the south.     

Do rivers and human-induced habitat fragmentation affect genetic diversity and population structure of the European ground squirrel at the edge of its Pannonian range?

The European ground squirrel (EGS) (Spermophilus citellus) populations of Vojvodina (Serbia) represent the southernmost part of its distribution in the Pannonian lowland. For species with low dispersal abilities a presence of even weak barriers can have significant influence on genetic structure among adjacent populations. We examined here the effects of habitat fragmentation and river barriers on the genetic structure of the EGS based on 12 microsatellite loci. Bayesian clustering methods were used as additions to classical population genetic approaches. We found that EGS populations in Vojvodina are highly fragmented, but their genetic variation is still higher than in peripheral populations in Central Europe. Populations in Vojvodina consistently grouped into three genetic clusters. The Danube, but not the Tisza River, represents an important barrier to gene flow. EGS populations in the studied area did not show the signs of recent genetic bottlenecks, as would be expected from observations of recent population declines. Conservation strategy should be focused on maintenance of remained suitable habitats and optimal population sizes.     

Genetic Diversity and Population Structure of the Rare and Endangered Plant Species Pulsatilla patens (L.) Mill in East Central Europe

Pulsatilla patens s.s. is a one of the most endangered plant species in Europe. The present range of this species in Europe is highly fragmented and the size of the populations has been dramatically reduced in the past 50 years. The rapid disappearance of P. patens localities in Europe has prompted the European Commission to initiate active protection of this critically endangered species. The aim of this study was to estimate the degree and distribution of genetic diversity within European populations of this endangered species. We screened 29 populations of P. patens using a set of six microsatellite primers. The results of our study indicate that the analyzed populations are characterized by low levels of genetic diversity (H_o = 0.005) and very high levels of inbreeding (F_IS = 0.90). These results suggest that genetic erosion could be partially responsible for the lower fitness in smaller populations of this species. Private allelic richness was very low, being as low as 0.00 for most populations. Average genetic diversity over loci and mean number of alleles in P. patens populations were significantly correlated with population size, suggesting severe genetic drift. The results of AMOVA point to higher levels of variation within populations than between populations.The results of Structure and PCoA analyses suggest that the genetic structure of the studied P. patens populations fall into three clusters corresponding to geographical regions. The most isolated populations (mostly from Romania) formed a separate group with a homogeneous gene pool located at the southern, steppic part of the distribution range. Baltic, mostly Polish, populations fall into two genetic groups which were not fully compatible with their geographic distribution.Our results indicate the serious genetic depauperation of P. patens in the western part of its range, even hinting at an ongoing extinction vortex. Therefore, special conservation attention is required to maintain the populations of this highly endangered species of European Community interest.     

Weak population genetic differentiation in the most numerous Arctic seabird,the little auk

Quantifying patterns of genetic diversity and differentiation among populations of Arctic birds is fundamental for understanding past and ongoing population processes in the Arctic. However, the genetic differentiation of many important Arctic species remains uninvestigated. Here, phylogeography and population genetics were examined in the worldwide population of a small seabird, the little auk (dovekie, Alle alle)—the most numerous avian species of the Arctic ecosystem. Blood samples or feathers were collected from 328 little auks (325 from the nominate subspecies and 3 from the A. a. polaris) in nine main breeding aggregations in the northern Atlantic and one location from the Pacific Ocean. The mtDNA haplotypes of the two subspecies were not segregated into separate groups. Also, no genetic structure was found within the nominate race based on microsatellite markers. The level of genetic differentiation among populations was low yet significant (mean F _ST = 0.005). Some pairwise F _ST comparisons revealed significant differences, including those involving the most distant Pacific colony as well as among some Atlantic populations. Weak population differentiation following the model of isolation by distance in the little auk is similar to the patterns reported in other high-Arctic bird species, indicating that a lack of distinct genetic structure is a common phenomenon in the Arctic avifauna.     

Genetic consequences of Pleistocene range shifts: contrast between the Arctic, the Alps and the East African mountains

In wide-ranging species, the genetic consequences of range shifts in response to climate change during the Pleistocene can be predicted to differ among different parts of the distribution area. We used amplified fragment length polymorphism data to compare the genetic structure of Arabis alpina, a widespread arctic-alpine and afro-alpine plant, in three distinct parts of its range: the North Atlantic region, which was recolonized after the last ice age, the European Alps, where range shifts were probably primarily altitudinal, and the high mountains of East Africa, where the contemporary mountain top populations result from range contraction. Genetic structure was inferred using clustering analyses and estimates of genetic diversity within and between populations. There was virtually no diversity in the vast North Atlantic region, which was probably recolonized from a single refugial population, possibly located between the Alps and the northern ice sheets. In the European mountains, genetic diversity was high and distinct genetic groups had a patchy and sometimes disjunct distribution. In the African mountains, genetic diversity was high, clearly structured and partially in accordance with a previous chloroplast phylogeography. The fragmented structure in the European and African mountains indicated that A. alpina disperses little among established populations. Occasional long-distance dispersal events were, however, suggested in all regions. The lack of genetic diversity in the north may be explained by leading-edge colonization by this pioneer plant in glacier forelands, closely following the retracting glaciers. Overall, the genetic structure observed corresponded to the expectations based on the environmental history of the different regions.     

High regional differentiation in a North American crab species throughout its native range and invaded European waters: a phylogeographic analysis

Rhithropanopeus harrisii (Gould 1841) has a native distribution from New Brunswick (Canada) to Veracruz (Mexico) and is considered an invasive species in northwestern North American (Oregon and California), South American (Brazil) and European estuaries and rivers. In Europe, it was observed for the first time in 1874, in The Netherlands. We sequenced and analyzed part of the cytochrome oxidase subunit I gene (mitochondrial DNA) of eight populations, three from the east coast of the United States of America (USA) and five from Europe, in order to assess their genetic diversity and to determine a potential founder population. European populations are characterized by a lower number of haplotypes than the whole native region of the eastern USA, suggesting that genetic bottlenecks occurred during the European colonisation. Along the North American East Coast, there is evidence of clearcut genetic heterogeneity, New Jersey being the most similar population in its genetic structure to the postulated Europe-founding population. Also the different European populations are heterogeneous and there is a tendency of higher genetic diversity in the populations founded earlier. R. harrisii is still in the process of expansion in Europe and may have been introduced once or repeatedly by different invasion mechanisms. The pronounced lack of gene flow among populations is of great ecological significance, since it may facilitate rapid adaptation and specialization to local conditions within single estuarine systems.     

Effect of habitat fragmentation on the genetic diversity and structure of peripheral populations of beech in Central Italy

Fragmentation can affect the demographic and genetic structure of populations near the boundary of their biogeographic range. Higher genetic differentiation among populations coupled with lower level of within-population variability is expected as a consequence of reduced population size and isolation. The effects of these 2 factors have been rarely disentangled. Given their high gene flow, anemophilous forest trees should be more affected, in terms of loss of genetic diversity, by small population size rather than geographic isolation alone. We studied the impact of distance from the main range (a measure of isolation) and reduced population size on the within-population and among population components of genetic variability. We assayed 11 isozyme loci in a total of 856 individuals in 27 marginal populations of European beech (Fagus sylvatica L.) in Central Italy. Populations were divided into 3 groups with an increasing level of fragmentation. In the most fragmented group, the within-population genetic variability was slightly smaller and the among population differentiation significantly larger than in the other 2 groups. Isolation-by-distance was lost when only pairs of populations involving at least one from the most fragmented group were considered and maintained in the other groups. These results support the role of random genetic drift having a larger impact on the most fragmented group, whereas gene flow seems to balance genetic drift in the 2 less fragmented ones. Given that average distance from the main range is not different between the intermediate and the most fragmented group, but average population size is smaller, we can conclude that gene flow is effective, even at relatively long distances, in balancing the effect of fragmentation if population size is not too small.     

Molecular phylogeny and population structure of the codling moth (Cydia pomonella) in Central Europe: II. AFLP analysis reflects human-aided local adaptation of a global pest species

Originally resident in southeastern Europe, the codling moth (Cydia pomonella L.) (Tortricidae) has achieved a nearly global distribution, being one of the most successful pest insect species known today. As shown in our accompanying study, mitochondrial genetic markers suggest a Pleistocenic splitting of Cydia pomonella into two refugial clades which came into secondary contact after de-glaciation. The actual distribution pattern shows, however, that Central European codling moths have experienced a geographic splitting into many strains and locally adapted populations, which is not reflected by their mitochondrial haplotype distribution. We therefore have applied, in addition to mitochondrial markers, an approach with a higher resolution potential at the population level, based on the analysis of amplification fragment length polymorphisms (AFLPs). As shown in the present study, AFLP markers elucidate the genetic structure of codling moth strains and populations from different Central European apple orchard sites. While individual genetic diversity within codling moth strains and populations was small, a high degree of genetic differentiation was observed between the analyzed strains and populations, even at a small geographic scale. One of the main factors contributing to local differentiation may be limited gene flow among adjacent codling moth populations. In addition, microclimatic, ecological, and geographic constraints also may favour the splitting of Cydia pomonella into many local populations. Lastly, codling moths in Central European fruit orchards may experience considerable selective pressure due to pest control activities. As a consequence of all these selective forces, today in Central Europe we see a patchy distribution of many locally adapted codling moth populations, each of them having its own genetic fingerprint. Because of the complete absence of any correlation between insecticide resistance and geographic or genetic distances among populations, AFLP markers do not have a prognostic value for predicting an outbreak of pesticide resistance in the field. By combining mitochondrial genetic data and AFLP analysis it was possible, however, to track the recent evolutionary history of Cydia pomonella on three different time scales: from population splitting in Pleistocene, to interbreeding of mitochondrial haplotypes in Holocene, to human-aided complete intermixing and splitting into many locally adapted populations in very recent times. The case of Cydia pomonella is reminiscent of examples of sympatric speciation and another example of a human-induced globally successful pest species.     

Effects of habitat fragmentation on the genetic structure of the monophagous butterfly Polyommatus coridon along its northern range margin

Population genetic patterns of species at their range margin have important implications for species conservation. We performed allozyme electrophoresis of 19 loci to investigate patterns of the genetic structure of 17 populations (538 individuals) of the butterfly Polyommatus coridon, a monophagous habitat specialist with a patchy distribution. The butterfly and its larval food plant Hippocrepis comosa reach their northern distribution margin in the study region (southern Lower Saxony, Germany). Butterfly population size increased with host plant population size. The genetic differentiation between populations was low but significant (FST = 0.013). No isolation-by-distance was found. Hierarchical F-statistics revealed significant differentiation between a western and an eastern subregion, separated by a river valley. The combination of genetic and ecological data sets revealed that the expected heterozygosity (mean: 18.5%) decreased with increasing distance to the nearest P. coridon population. The population size of P. coridon and the size of larval food plant population had no effect on the genetic diversity. The genetic diversity of edge populations of P. coridon was reduced compared to populations from the centre of its distribution. This might be explained by (i). an increasing habitat fragmentation towards the edge of the distribution range and/or (ii). a general reduction of genetic variability towards the northern edge of its distribution.     

Intriguing small-scale spatial distribution of chloropastic and nuclear diversity in the endangered plant Biscutella neustriaca (Brassicaceae)

Biscutella neustriaca is an isolated plant taxon with about three thousand known individuals distributed in several fragmented populations. Despite its status as an endangered plant subject to a European LIFE programme for its protection, no conclusive genetic analysis has been performed to help its conservation. We analysed the genetic variability and distribution of nuclear microsatellite markers in a large sample of the population, as well as of the MatK chloroplastic gene in a subsample. We showed, first, that both pollen and seed dispersal, as well as clonal reproduction are strongly limited, and the mating system is obligate outcrossing. Second, we detected two highly divergent chloroplast haplogroups, as well as two completely distinct nuclear gene pools suggesting an ancient isolation between two groups of populations. Intriguingly, a third group of populations appears to combine the nuclear gene pool of one group with the chloroplast haplotype of the other group, suggesting a more recent dramatic colonization and foundation event. Thanks to complementary geological and historical data, we propose a scenario for the evolutionary history of this metapopulation influenced by the dynamics of Seine meanders and human activities. Finally, we give some suggestions for future conservation actions.