Genetic differentiation of southeast Baltic populations of sea trout inferred from single nucleotide polymorphisms

Sea trout (Salmo trutta m. trutta) is a migratory form of brown trout common in the Baltic Sea. Nine populations from the southeast Baltic (Poland; Lithuania; Denmark, Bornholm; Estonia and Russia) were genotyped using iPLEX Gold technology (Sequenom) with 62 informative SNPs. A diagnostic panel of 23 SNPs was applied to estimate genetic differentiation and assess the population structure of Baltic sea trout. The highest level of pairwise F_ST differences was observed between the Russian (East Gulf of Finland) and Polish (Baltic main basin) populations. The lowest differences were between the two Polish and the Polish and Lithuanian populations. A genetic similarity was noted between the Estonian Riguldi River and Danish Bornholm populations, and this finding was supported by a Bayesian and factorial correspondence analysis. Diversity within populations was highest for populations from Estonia and lowest for the Lithuanian population. Genetic structure analysis indicated that individuals from the nine populations were clustered into four groups.     

Genetic connectivity among swarming sites in the wide ranging and recently declining little brown bat (Myotis lucifugus)

Characterizing movement dynamics and spatial aspects of gene flow within a species permits inference on population structuring. As patterns of structuring are products of historical and current demographics and gene flow, assessment of structure through time can yield an understanding of evolutionary dynamics acting on populations that are necessary to inform management. Recent dramatic population declines in hibernating bats in eastern North America from white‐nose syndrome have prompted the need for information on movement dynamics for multiple bat species. We characterized population genetic structure of the little brown bat, Myotis lucifugus, at swarming sites in southeastern Canada using 9 nuclear microsatellites and a 292‐bp region of the mitochondrial genome. Analyses of F_ST, Φ_ST, and Bayesian clustering (STRUCTURE) found weak levels of genetic structure among swarming sites for the nuclear and mitochondrial genome (Global F_ST = 0.001, P < 0.05, Global Φ_ST = 0.045, P < 0.01, STRUCTURE K = 1) suggesting high contemporary gene flow. Hierarchical AMOVA also suggests little structuring at a regional (provincial) level. Metrics of nuclear genetic structure were not found to differ between males and females suggesting weak asymmetries in gene flow between the sexes. However, a greater degree of mitochondrial structuring does support male‐biased dispersal long term. Demographic analyses were consistent with past population growth and suggest a population expansion occurred from approximately 1250 to 12,500 BP, following Pleistocene deglaciation in the region. Our study suggests high gene flow and thus a high degree of connectivity among bats that visit swarming sites whereby mainland areas of the region may be best considered as one large gene pool for management and conservation.     

Genetic structure of Polytrichum formosum in relation to the breeding system as revealed by microsatellites

Microsatellite variation was determined for three Danish and three Dutch populations of the haploid moss species Polytrichum formosum to gain insight into the relative importance of sexual vs. asexual reproduction for the amount and structure of genetic variation. In general, low levels of microsatellite variation were observed within this species. Even when estimated for polymorphic loci only, the levels of microsatellite variability (P=90.6, A=4.3 and H_S=0.468) within populations were on average lower than those reported for most other plant species. In contrast, genotypic diversity was high within each of the examined populations, indicating that sexual reproduction is a very important determinant of the genetic structure of P. formosum within populations. In agreement with previous findings for allozyme data, no significant genetic differentiation (F_ST=0.028, R_ST=0.015) was observed neither between populations nor between regions approximately 450 km apart (Denmark vs. the Netherlands). These low levels of population differentiation observed for both types of genetic markers are probably best explained by a high level of effective spore dispersal (gene flow) between populations. Therefore, also on a large geographical scale sexual reproduction is the most important determinant of the genetic structure of P. formosum, despite the high potential to reproduce clonally.     

Admixture and Gene Flow from Russia in the Recovering Northern European Brown Bear (Ursus arctos)

Large carnivores were persecuted to near extinction during the last centuries, but have now recovered in some countries. It has been proposed earlier that the recovery of the Northern European brown bear is supported by migration from Russia. We tested this hypothesis by obtaining for the first time continuous sampling of the whole Finnish bear population, which is located centrally between the Russian and Scandinavian bear populations. The Finnish population is assumed to experience high gene flow from Russian Karelia. If so, no or a low degree of genetic differentiation between Finnish and Russian bears could be expected. We have genotyped bears extensively from all over Finland using 12 validated microsatellite markers and compared their genetic composition to bears from Russian Karelia, Sweden, and Norway. Our fine masked investigation identified two overlapping genetic clusters structured by isolation-by-distance in Finland (pairwise F_ST = 0.025). One cluster included Russian bears, and migration analyses showed a high number of migrants from Russia into Finland, providing evidence of eastern gene flow as an important driver during recovery. In comparison, both clusters excluded bears from Sweden and Norway, and we found no migrants from Finland in either country, indicating that eastern gene flow was probably not important for the population recovery in Scandinavia. Our analyses on different spatial scales suggest a continuous bear population in Finland and Russian Karelia, separated from Scandinavia.     

Genetic indications of translocated and stocked grey partridges (Perdix perdix): does the indigenous Danish grey partridge still exist?

Non‐local population stocking can have adverse genetic effects on wild populations through loss of genetic diversity and introgressive hybridization. The grey partridge (Perdix perdix) has been an important European game species for centuries, widely subject to translocation and stocking. After c. 80 years of releasing reared grey partridges in Denmark, this study investigated whether an indigenous Danish grey partridge still existed. If so, they would (1) belong to the western European clade (W1) and (2) be more closely related to the historical, indigenous grey partridges than to farm‐bred partridges. These predictions were tested by analysing the variation in both the mitochondrial control region (CR1) and microsatellite markers in museum samples representing the ancestral indigenous Danish grey partridge, contemporary wild grey partridges and farmed grey partridges from the five largest farms in Denmark. Phylogeography and population structure analyses showed traces of the indigenous Danish grey partridges amongst recent wild partridges in certain areas and significant genetic differences between farmed partridges and historical and recent partridges. The results also showed that the indigenous Danish grey partridges belonged to the western European clade (W1 haplotype). A foreign stocking effect was detected on the remote island of Bornholm, where the current population originated from introduced Danish and Bohemian grey partridges. The loss of haplotype diversity over time in certain geographical areas probably results from serious declines in wild Danish grey partridge numbers in recent decades. This, combined with the observation that hybridization between released stocked and wild partridges can occur, may complicate recovery of partridge populations. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 694–710.     

Grain aphid population structure: no effect of fungal infections in a 2-year field study in Denmark

1 Sitobion avenae (F.) is a serious pest in Danish cereal crops. To understand the population genetic structure, aphids were sampled in seven different winter wheat (Triticum sativum Lamarck) fields throughout Denmark. The aphids were genotyped with seven microsatellite markers. In total, 2075 aphids were collected and 1203 of these were genotyped. 2 The Danish S. avenae populations displayed very high genotypic diversity, high percentages of unique genotypes and low linkage disequilibria; this is likely to be a result of genetic recombination encompassed by their holocyclic lifestyle. The populations showed very limited differentiation and no sign of isolation by distance. Almost all the genetic variation was ascribed within the populations rather than between populations, probably due to a high migration rate at approximate 10% per generation. 3 Seasonal changes in clonal diversity and distribution of asexual summer generations of S. avenae within the infestation period in a single winter wheat field were followed over two consecutive years by weekly sampling from 60 plots each of 20 × 20 m. Clonal diversity was high in all samples with no dominant clonal lineages and no significant difference in the genotypic diversity between weeks or between years. However, a temporal genetic differentiation effect, throughout the infestation, suggests that selective factors or high temporal migration play an important role in shaping the genetic structure S. avenae. 4 Analyses of fungal infected and uninfected aphids were performed to test whether some clonal linage were more often infected by fungi from the Entomophthorales under field conditions. In total, 54 progeny from aphids with Entomophthorales were genotyped and compared with 422 uninfected aphid genotypes. The Entomophthorales‐infected aphid genotypes did not cluster out together, suggesting that these fungal pathogens did not affect the population differentiation or clonal distribution of S. avenae in a Danish agroecosystem. 5 Our findings indicate that S. avenae populations can be controlled using conservation biological control     

Population Structure of the Giant Garter Snake, Thamnophis gigas

The giant garter snake, Thamnophis gigas, is a threatened species endemic to California’s Central Valley. We tested the hypothesis that current watershed boundaries have caused genetic differentiation among populations of T. gigas. We sampled 14 populations throughout the current geographic range of T. gigas and amplified 859 bp from the mitochondrial gene ND4 and one nuclear microsatellite locus. DNA sequence variation from the mitochondrial gene indicates there is some genetic structuring of the populations, with high F_ST values and unique haplotypes occurring at high frequency in several populations. We found that clustering populations by watershed boundary results in significant between-region genetic variance for mtDNA. However, analysis of allele frequencies at the microsatellite locus NSU3 reveals very low F_ST values and little between-region variation in allele frequencies. The discordance found between mitochondrial and microsatellite data may be explained by aspects of molecular evolution and/or T. gigas life history characteristics. Differences in effective population size between mitochondrial and nuclear DNA, or male-biased gene flow, result in a lower migration rate of mitochondrial haplotypes relative to nuclear alleles. However, we cannot exclude homoplasy as one explanation for homogeneity found for the single microsatellite locus. The mitochondrial nucleotide sequence data supports conservation practices that identify separate management units for T. gigas.     

Dynamic micro-geographic and temporal genetic diversity in vertebrates: the case of lake-spawning populations of brown trout (Salmo trutta)

Conservation of species should be based on knowledge of effective population sizes and understanding of how breeding tactics and selection of recruitment habitats lead to genetic structuring. In the stream‐spawning and genetically diverse brown trout, spawning and rearing areas may be restricted source habitats. Spatio–temporal genetic variability patterns were studied in brown trout occupying three lakes characterized by restricted stream habitat but high recruitment levels. This suggested non‐typical lake‐spawning, potentially representing additional spatio–temporal genetic variation in continuous habitats. Three years of sampling documented presence of young‐of‐the‐year cohorts in littoral lake areas with groundwater inflow, confirming lake‐spawning trout in all three lakes. Nine microsatellite markers assayed across 901 young‐of‐the‐year individuals indicated overall substantial genetic differentiation in space and time. Nested gene diversity analyses revealed highly significant (≤P = 0.002) differentiation on all hierarchical levels, represented by regional lakes (F_LT = 0.281), stream vs. lake habitat within regional lakes (F_HL = 0.045), sample site within habitats (F_SH = 0.010), and cohorts within sample sites (F_CS = 0.016). Genetic structuring was, however, different among lakes. It was more pronounced in a natural lake, which exhibited temporally stable structuring both between two lake‐spawning populations and between lake‐ and stream spawners. Hence, it is demonstrated that lake‐spawning brown trout form genetically distinct populations and may significantly contribute to genetic diversity. In another lake, differentiation was substantial between stream‐ and lake‐spawning populations but not within habitat. In the third lake, there was less apparent spatial or temporal genetic structuring. Calculation of effective population sizes suggested small spawning populations in general, both within streams and lakes, and indicates that the presence of lake‐spawning populations tended to reduce genetic drift in the total (meta‐) population of the lake.     

Host and parasite life history interplay to yield divergent population genetic structures in two ectoparasites living on the same bat species

Host–parasite interactions are ubiquitous in nature. However, how parasite population genetic structure is shaped by the interaction between host and parasite life history remains understudied. Studies comparing multiple parasites infecting a single host can be used to investigate how different parasite life history traits interplay with host behaviour and life history. In this study, we used 10 newly developed microsatellite loci to investigate the genetic structure of a parasitic bat fly (Basilia nana). Its host, the Bechstein's bat (Myotis bechsteinii), has a social system and roosting behaviour that restrict opportunities for parasite transmission. We compared fly genetic structure to that of the host and another parasite, the wing‐mite, Spinturnix bechsteini. We found little spatial or temporal genetic structure in B. nana, suggesting a large, stable population with frequent genetic exchange between fly populations from different bat colonies. This contrasts sharply with the genetic structure of the wing‐mite, which is highly substructured between the same bat colonies as well as temporally unstable. Our results suggest that although host and parasite life history interact to yield similar transmission patterns in both parasite species, the level of gene flow and eventual spatiotemporal genetic stability is differentially affected. This can be explained by the differences in generation time and winter survival between the flies and wing‐mites. Our study thus exemplifies that the population genetic structure of parasites on a single host can vary strongly as a result of how their individual life history characteristics interact with host behaviour and life history traits.     

The Scotch broom,Cytisus scoparius (Fabaceae), a paradox in Denmark – an invasive plant or endangered native species?

Scotch broom, Cytisus scoparius, spreads rapidly in parts of Denmark and is considered an invasive species by some authors. However, the species has been present in the Danish flora for centuries and is therefore considered native to Denmark. In the present study we explore whether Danish Scotch broom consists of one or two gene pools with potential differences in phenotype and invasiveness. One plastid and five nuclear microsatellite markers were used to reveal potential substructuring of Danish Scotch broom. Nine populations were included representing populations exhibiting invasive behaviour and populations showing non‐invasive behaviour. An Italian population was used as reference. Bayesian analysis based on genetic markers indicated that the sampled populations form two distinct gene pools, and this pattern was supported by neighbour‐joining trees. Measurements of height and width of the analysed plants showed that the two gene pools correspond to populations exhibiting either a horizontal habit and non‐invasive behaviour or an erect habit and, in some cases, invasive behaviour. The Italian population clustered with the erect ones. We discuss the origin and taxonomic status of the two gene pools and conclude that Danish horizontal Scotch broom should be given a formal taxonomic status in order to initiate conservation activities for its protection. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Population genetic structure and colonization history of short ninespine sticklebacks (Pungitius kaibarae)

The contemporary distribution and genetic structure of a freshwater fish provide insight into its historical geodispersal and geographical isolation following Quaternary climate changes. The short ninespine stickleback, Pungitius kaibarae, is a small gasterosteid fish occurring in freshwater systems on the Korean Peninsula and in southeast Russia. On the Korean Peninsula, P. kaibarae populations are distributed in three geographically separated regions: the NE (northeast coast), SE (southeast coast), and a limited area in the ND (Nakdong River). In this study, we used mitochondrial loci and microsatellites to investigate the evolutionary history of P. kaibarae populations by assessing their pattern of genetic structure. Our analyses revealed a marked level of divergence among three regional populations, suggesting a long history of isolation following colonization, although ND individuals showed relatively higher genetic affinity to populations from SE than those from NE. The populations from NE showed a great degree of interpopulation differentiation, whereas populations from SE exhibited only weak genetic structuring. Upon robust phylogenetic analysis, P. kaibarae formed a monophyletic group with Russian P. sinensis and P. tymensis with strong node confidence values, indicating that P. kaibarae populations on the Korean Peninsula originated from the southward migration of its ancestral lineage around the middle Pleistocene.     

Population structure of the dusky pipefish (Syngnathus floridae) from the Atlantic and Gulf of Mexico,as revealed by mitochondrial DNA and microsatellite analyses

Aim To elucidate the historical phylogeography of the dusky pipefish (Syngnathus floridae) in the North American Atlantic and Gulf of Mexico ocean basins. Location Southern Atlantic Ocean and northern Gulf of Mexico within the continental United States. Methods A 394‐bp fragment of the mitochondrial cytochrome b gene and a 235‐bp fragment of the mitochondrial control region were analysed from individuals from 10 locations. Phylogenetic reconstruction, haplotype network, mismatch distributions and analysis of molecular variance were used to infer population structure between ocean basins and time from population expansion within ocean basins. Six microsatellite loci were also analysed to estimate population structure and gene flow among five populations using genetic distance methods (F_ST, Nei’s genetic distance), isolation by distance (Mantel’s test), coalescent‐based estimates of genetic diversity and migration patterns, Bayesian cluster analysis and bottleneck simulations. Results Mitochondrial analyses revealed significant structuring between ocean basins in both cytochrome b (Φ_ST = 0.361, P < 0.0001; Φ_CT = 0.312, P < 0.02) and control region (Φ_ST = 0.166, P < 0.0001; Φ_CT = 0.128, P < 0.03) sequences. However, phylogenetic reconstructions failed to show reciprocal monophyly in populations between ocean basins. Microsatellite analyses revealed significant population substructuring between all locations sampled except for the two locations that were in closest proximity to each other (global F_ST value = 0.026). Bayesian analysis of microsatellite data also revealed significant population structuring between ocean basins. Coalescent‐based analyses of microsatellite data revealed low migration rates among all sites. Mismatch distribution analysis of mitochondrial loci supports a sudden population expansion in both ocean basins in the late Pleistocene, with the expansion of Atlantic populations occurring more recently. Main conclusions Present‐day populations of S. floridae do not bear the mitochondrial DNA signature of the strong phylogenetic discontinuity between the Atlantic and Gulf coasts of North America commonly observed in other species. Rather, our results suggest that Atlantic and Gulf of Mexico populations of S. floridae are closely related but nevertheless exhibit local and regional population structure. We conclude that the present‐day phylogeographic pattern is the result of a recent population expansion into the Atlantic in the late Pleistocene, and that life‐history traits and ecology may play a pivotal role in shaping the realized geographical distribution pattern of this species.     

Genetic structure of the northwestern Russian wolf populations and gene flow between Russia and Finland

We examined the genetic diversity and structure of wolf populations in northwestern Russia. Populations in Republic of Karelia and Arkhangelsk Oblast were sampled during 1995–2000, and 43 individuals were genotyped with 10 microsatellite markers. Moreover, 118 previously genotyped wolves from the neighbouring Finnish population were used as a reference population. A relatively large amount of genetic variation was found in the Russian populations, and the Karelian wolf population tended to be slightly more polymorphic than the Arkhangelsk population. We found significant inbreeding (F = 0.094) in the Karelian, but not in the Arkhangelsk population. The effective size estimates of the Karelian wolf population based on the approximate Bayesian computation and linkage disequilibrium methods were 39.9 and 46.7 individuals, respectively. AMOVA-analysis and exact test of population differentiation suggested clear differentiation between the Karelian, Arkhangelsk and Finnish wolf populations. Indirect estimates of gene flow based on the level of population differentiation (ϕ _ST  = 0.152) and frequency of private alleles (0.029) both suggested a low level of gene flow between the populations (Nm = 1.4 and Nm = 3.7, respectively). Assignment analysis of Karelian and Finnish populations suggested an even lower number of recent migrants (less than 0.03) between populations, with a larger amount of migration from Finland to Karelia than vice versa. Our findings emphasise the role of physical obstacles and territorial behaviour in creating barriers to gene flow between populations in relatively limited geographical areas, even in large-bodied mammalian species with long-distance dispersal capabilities and an apparently continuous population structure.     

Microsatellite‐based analysis of genetic structure and gene flow of Mythimna separata (Walker) (Lepidoptera: Noctuidae) in China

The oriental armyworm, Mythimna separata, is a serious agricultural pest in China. Seasonal and roundtrip migration has recently led to sudden, localized outbreaks and crop losses. To evaluate genetic differentiation between populations in eastern and western China and elucidate gene flow, the genetic structure of 20 natural populations from nine provinces was examined using seven microsatellite markers. The results indicated high genetic diversity. However, little to moderate (0 < F_ST < 0.15) genetic differentiation was detected, and there was no correlation between genetic distance and geographical distance. Bayesian clustering analysis identified three groups whereas discriminant analysis of principal components identified ten clusters that were considered as two clear‐cut clusters and one admixed group. Gene flow occurred frequently in most population pairs, and an asymmetrical migration rate was detected in several pairwise population comparisons. The bottleneck test showed that few populations had experienced recent bottlenecks. Correspondingly, large‐scale and long‐distance migration of M. separata has caused low genetic differentiation and frequent gene exchange. Our findings are important for studying genetic evolution and help to improve predictions of M. separata outbreaks in China.     

Genetic structure of the Danish red deer (Cervus elaphus)

The red deer (Cervus elaphus) population in Denmark became almost extinct in recent historical times due to over‐hunting. The species has subsequently recovered within remote areas, but non‐Danish individuals have been introduced at several localities. To assess genetic structure, past demographic history, and the possibility of a still existing original stock, we analysed 349 specimens from 11 geographically separate areas and from three enclosed areas, genotyping 11 microsatellite loci. Moreover, an 826‐bp fragment of the control region of the mitochondrial DNA was sequenced for 116 recent specimens and seven museum specimens. There was a significant difference in mean expected heterozygosity (H_E) between the three enclosed areas and the 11 unenclosed areas. Significant departures from Hardy–Weinberg equilibrium were observed in the three enclosed areas and in nine of the unenclosed areas. The overall degree of genetic differentiation among all 14 areas was significant (F_ST = 0.09, P < 0.01), primarily because the mean pairwise F_ST for the three enclosed areas was significantly higher than that for the 11 unenclosed areas. A Bayesian clustering procedure detected three genetically distinct populations and indicated reduced gene flow between the enclosed and unenclosed areas. The individuals in the unenclosed areas show genotypic mixture, presumably as a result of gene flow among them. Markov Chain Monte Carlo simulations, based on the genealogical history of the microsatellite alleles, suggest a drastic decline in the effective population size of the enclosed areas some 188–474 years ago. Mitochondrial DNA analysis of the recent specimens showed seven haplotypes. Individuals from the enclosed Jægersborg Dyrehave contain haplotypes that occur all over Denmark and also are found in Western Europe. A close relationship between Scandinavian and Western European red deer is most likely. Only individuals from the unenclosed Lindenborg Estate and the enclosed Tofte Skov did not group with any other Danish individuals. As six of seven museum specimens had haplotypes also found in modern Danish samples, the current population of red deer in Denmark is genetically close to the original Danish red deer. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 688–701.     

Local adaptation through genetic differentiation in highly fragmented Tilia cordata populations

We assessed the level of geographic differentiation of Tilia cordata in Denmark based on tests of 91 trees selected from 12 isolated populations. We used quantitative analysis of spring phenology and population genetic analysis based on SSR markers to infer the likely historical genetic processes within and among populations. High genetic variation within and among populations was observed in spring phenology, which correlated with spring temperatures at the origin of the tested T. cordata trees. The population genetic analysis revealed significant differentiation among the populations, but with no clear sign of isolation by distance. We infer the findings as indications of ongoing fine scale selection in favor of local growth conditions made possible by limited gene flow among the small and fragmented populations. This hypothesis fits well with reports of limited fruiting in the investigated Danish T. cordata populations, while the species is known for its ability to propagate vegetatively by root suckers. Our results suggest that both divergent selection and genetic drift may have played important roles in forming the genetic patterns of T. cordata at its northern distribution limit. However, we also speculate that epigenetic mechanism arising from the original population environment could have created similar patterns in regulating the spring phenology.     

Regional and local spatial genetic structure of Siberian primrose populations in Northern Europe

We have investigated the local and regional scale genetic structure of Siberian primrose (Primula nutans) populations in Northern Europe. The genetic diversity and structure of fifteen populations sampled from the Bothnian Bay in Finland, the Barents Sea in Norway and the White Sea in Russia were assessed using eleven microsatellite markers. We investigated the distribution of genetic variation within and between populations, and studied the local genetic structure using spatial autocorrelation analysis. We found very low genetic and allelic diversity in the Bothnian Bay and Barents Sea populations, and only slightly higher in the White Sea population. The level of genetic differentiation between the regions was very high, whereas differentiation between the populations within the regions was moderate. We found no spatial structuring of populations in any region suggesting efficient dispersal on a local scale. Clonal reproduction seemed to have no effect on genetic structure.     

Genetic and geographic structure of an insect resistant and a susceptible type of <Emphasis Type="Italic">Barbarea vulgaris</Emphasis> in western Europe

Interactions between herbivores and plants are believed to have been important drivers of biodiversity. However, to drive an initial resistance divergence into different evolutionary lineages and taxa, these interactions have probably been embedded in other processes of divergence, like allopatric isolation. The cruciferous plant Barbarea vulgaris ssp. arcuata occurs in Denmark in two types: one (G) is resistant to most genotypes of the flea beetle Phyllotreta nemorum, the other (P) is susceptible. The two types additionally differ in hairiness and glucosinolates, they are genetically strongly divergent, and reproduction between them is reduced. To determine whether the two plant types and their resistance polymorphisms are also present outside Denmark, and to understand how they have evolved, we analysed 33 European populations of B. vulgaris for resistance, hairiness, glucosinolates, and microsatellite markers. Most populations had traits indicative of the G type, including the already characterized Danish G populations. In contrast, only two populations outside Denmark were of the P type; one from northern Sweden and one from Estonia. Genetically, the G populations formed two genetic clusters that were strongly divergent from a genetic cluster containing P populations. A fourth genetic cluster, which contained only a single population and no Danish plants, belonged morphologically to the subspecies ssp. vulgaris. The divergence found in Denmark between a resistant G and a susceptible P type is thus part of a larger divergence in Europe. Judging from the trait correlations, genetic divergence, and partial reproductive incompatibility, the plant types must have been isolated from each other for quite some time. The two P populations outside Denmark came from the north and east, suggesting a more eastern distribution. If so, resistant and susceptible types could have diverged during the ice age and later met in Scandinavia. However, more samples from Eastern Europe are needed to clarify this.     

Genetic structure within and among regional populations of the Eurasian badger (Meles meles) from Denmark and the Netherlands

The Eurasian badger Meles meles has a wide distribution area ranging from Japan to Ireland. In western Europe badger habitats are severely disturbed by anthropogenic factors, leading to fragmentation into subpopulations and formation of a metapopulation substructuring of once continuous panmictic populations. We have examined the genetic structure of Dutch and Danish badger populations on a relatively small scale (within countries) and a larger scale (between countries). The levels of genetic variation of populations were moderate and did not differ significantly among populations (overall H _O=0.30, overall H _E=0.34). Considerable genetic differentiation between the Dutch and Danish populations was found (overall F _ST=0.32, mean pairwise Dutch–Danish F _ST=0.42), indicating a large-scale substructuring of these western European badger populations. Further analysis showed that the Danish badger population can be substructured into three clusters [ P _{( k =3)}=0.99], but the Dutch populations cluster into one more or less panmictic population [ P _{( k =1)}=0.99] with little or no substructuring. The presence of migration barriers, such as roads, together with the peninsular geography of Denmark, may have led to this structuring of badger populations. In contrast, measures that improve migration and connection to other populations from neighboring countries may have prevented substructuring of the Dutch badger population.     

Genetic structure of freshwater Atlantic salmon (<Emphasis Type="Italic">Salmo salar</Emphasis> L.) populations from the lakes Onega and Ladoga of northwest Russia and implications for conservation

Freshwater Atlantic salmon (Salmo salar L.) populations are a living example of adaptation to the changing conditions caused by glacial cycles. The uniqueness of these populations is emphasized by almost complete resistance to the dangerous parasite Gyrodactylus salaris. In Europe, freshwater salmon populations occur primarily in north-western Russia in the republic of Karelia. These systems include Lakes Ladoga and Onega, the two largest lakes in Europe, each of which harbours a number of freshwater salmon spawning rivers. We used microsatellite markers to study the genetic structure and temporal stability of 11 freshwater salmon populations in Russian Karelia. Populations clustered according their region of origin. Although temporal variation in allele frequencies was observed in the majority of temporal comparisons, various lines of evidence demonstrated that this influence was relatively minor compared to spatial variation that explained eight times more of the variability than temporal variation. Temporal stability tended to occur in populations from rivers with a higher linear lake coefficient. The high level of genetic structuring observed in both lake systems and the apparent low level of migration between populations suggests that treating each river as a separate management unit is recommended. In addition, as the number of populations is large, the best strategy for such fine scale management would be to ensure that the level of natural reproduction in each river is sufficient to sustain the population. A prioritization strategy for population conservation based on estimating the relative roles of different evolutionary forces shaping the gene pools highlighted a number of populations where further monitoring is warranted and also identified populations which could be prioritized for conservation as living gene banks in the event that conservation resources are limited. This prioritization agreed well with the occurrence of temporal (in)stability.