Contrasting patterns of mitochondrial and microsatellite genetic structure among Western European populations of tawny owls (Strix aluco)

A recent study of mitochondrial phylogeography of tawny owls (Strix aluco) in western Europe suggested that this species survived the Pleistocene glaciations in three allopatric refugia located in Iberia, Italy, and the Balkans, and the latter was likely the predominant source of postglacial colonization of northern Europe. New data from seven microsatellite loci from 184 individual owls distributed among 14 populations were used to assess the genetic congruence between nuclear and mitochondrial DNA (mtDNA) markers. Microsatellites corroborated the major phylogeographical conclusions reached on the basis of the mtDNA sequences, but also showed important differences leading to novel inferences. Microsatellites corroborated the three major refugia and supported the Balkan origin of northern populations. When corrected for differences in effective population size, microsatellites and mtDNA yielded generally congruent overall estimates of population structure (N*ST=0.12 vs. RST=0.16); however, there was substantial heterogeneity in the RST among the seven nuclear loci that was not correlated with heterozygosity. Populations representing the Balkans postglacial expansion interact with populations from the other two refugia forming two clines near the Alps and the Pyrenees. In both cases, the apparent position of the contact zones differed substantially between markers due to the genetic composition of populations sampled in northern Italy and Madrid. Microsatellite data did not corroborate the lower genetic diversity of northern, recently populated regions as was found with mtDNA; this discrepancy was taken as evidence for a recent bottleneck recovery. Finally, this study suggests that congruence among genetic markers should be more likely in cases of range expansion into new areas than when populations interact across contact zones.     

Postglacial colonization of Europe by the barbastelle bat: agreement between molecular data and past predictive modelling

The barbastelle (Barbastella barbastellus) is a rare forest bat with a wide distribution in Europe. Here, we combine results from the analysis of two mtDNA fragments with species distribution modelling to determine glacial refugia and postglacial colonization routes. We also investigated whether niche conservatism occurs in this species. Glacial refugia were identified in the three southern European peninsulas: Iberia, Italy and the Balkans. These latter two refugia played a major role in the postglacial colonization process, with their populations expanding to England and central Europe, respectively. Palaeo‐distribution models predicted that suitable climatic conditions existed in the inferred refugia during the last glacial maximum (LGM). Nevertheless, the overlap between the current and the LGM distributions was almost inexistent in Italy and in the Balkans, meaning that B. barbastellus populations were forced to shift range between glacial and interglacial periods, a process that probably caused some local extinctions. In contrast, Iberian populations showed a ‘refugia within refugium’ pattern, with two unconnected areas containing stable populations (populations that subsisted during both glacial and interglacial phases). Moreover, the match between LGM models and the refugial areas determined by molecular analysis supported the hypothesis of niche conservatism in B. barbastellus. We argue that geographic patterns of genetic structuring, altogether with the modelling results, indicate the existence of four management units for conservation: Morocco, Iberia, Italy and UK, and Balkans and central Europe. In addition, all countries sampled possessed unique gene pools, thus stressing the need for the conservation of local populations.     

Evidence for strong genetic structure in European populations of the little owl Athene noctua

The little owl Athene noctua is a widespread species in Europe. This mainly sedentary owl experienced reduction in population sizes in some areas due to habitat loss and modification of the landscape. To assess the genetic structure of the populations of western and central Europe, we analysed 333 specimens from 15 geographical areas at 13 microsatellite loci. Statistical analyses and Bayesian clustering procedures detected two major genetically distinct clusters, the first distributed from Portugal to the Czech Republic and the second from the Balkans to Italy. The second cluster was further split into three groups, located in Italy, Sardinia and the Balkans. These groups match four previously‐described mtDNA haplogroups, and probably originated from the isolation of little owl populations in Sardinia and in three glacial refugia (Iberia, south Italy and Balkans) during the ice ages. High genetic admixture was recorded in central and northern Europe, probably as a consequence of the expansion from the refugia during interglacial. The main colonization route originated from the Iberian Peninsula towards central and northern Europe. Contact zones with colonization events from Italy and the Balkans were detected respectively in northern Italy and central Europe. Genetic indices show the existence of moderate levels of genetic variability throughout Europe, although evidence of recent evolutionary bottlenecks was found in some populations. Estimation of migration rates and approximate Bayesian computations highlighted the most likely phylogeographical scenario for the current distribution of little owl populations.     

Out of Anatolia: longitudinal gradients in genetic diversity support an eastern origin for a circum-Mediterranean oak gallwasp Andricus quercustozae

Many studies have addressed the latitudinal gradients in intraspecific genetic diversity of European taxa generated during postglacial range expansion from southern refugia. Although Asia Minor is known to be a centre of diversity for many taxa, relatively few studies have considered its potential role as a Pleistocene refugium or a potential source for more ancient westward range expansion into Europe. Here we address these issues for an oak gallwasp, Andricus quercustozae (Hymenoptera: Cynipidae), whose distribution extends from Morocco along the northern coast of the Mediterranean through Turkey to Iran. We use sequence data for a fragment of the mitochondrial gene cytochrome b and allele frequency data for 12 polymorphic allozyme loci to answer the following questions: (1) which regions represent current centres of genetic diversity for A. quercustozae? Do eastern populations represent one refuge or several discrete glacial refugia? (2) Can we infer the timescale and sequence of the colonization processes linking current centres of diversity? Our results suggest that A. quercustozae was present in five distinct refugia (Iberia, Italy, the Balkans, southwestern Turkey and northeastern Turkey) with recent genetic exchange between Italy and Hungary. Genetic diversity is greatest in the Turkish refugia, suggesting that European populations are either (a) derived from Asia Minor, or (b) subject to more frequent population bottlenecks. Although Iberian populations show the lowest diversity for putatively selectively neutral markers, they have colonized a new oak host and represent a genetically and biologically discrete entity within the species.     

Late‐glacial recolonization and phylogeography of European red deer (Cervus elaphus L.)

The Pleistocene was an epoch of extreme climatic and environmental changes. How individual species responded to the repeated cycles of warm and cold stages is a major topic of debate. For the European fauna and flora, an expansion–contraction model has been suggested, whereby temperate species were restricted to southern refugia during glacial times and expanded northwards during interglacials, including the present interglacial (Holocene). Here, we test this model on the red deer (Cervus elaphus) a large and highly mobile herbivore, using both modern and ancient mitochondrial DNA from the entire European range of the species over the last c. 40 000 years. Our results indicate that this species was sensitive to the effects of climate change. Prior to the Last Glacial Maximum (LGM) haplogroups restricted today to South‐East Europe and Western Asia reached as far west as the UK. During the LGM, red deer was mainly restricted to southern refugia, in Iberia, the Balkans and possibly in Italy and South‐Western Asia. At the end of the LGM, red deer expanded from the Iberian refugium, to Central and Northern Europe, including the UK, Belgium, Scandinavia, Germany, Poland and Belarus. Ancient DNA data cannot rule out refugial survival of red deer in North‐West Europe through the LGM. Had such deer survived, though, they were replaced by deer migrating from Iberia at the end of the glacial. The Balkans served as a separate LGM refugium and were probably connected to Western Asia with genetic exchange between the two areas.     

Rangewide phylogeography of a bird-dispersed Eurasian shrub: contrasting Mediterranean and temperate glacial refugia

We studied the phylogeography of alder buckthorn (Frangula alnus), a bird-dispersed shrub or small tree distributed over most of Europe and West Asia and present in three of the four main refugia of West Palaearctic temperate woody plants: the Iberian Peninsula, the Balkans and Anatolia. A total of 78 populations from 21 countries were analysed for chloroplast DNA variation using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and 21 different haplotypes were distinguished. We found a very strong overall population differentiation (GST = 0.81) and phylogeographical structure, and a sharp contrast between the haplotype-rich refugia and the almost completely uniform area of postglacial colonization. The haplotype network comprises three lineages made up of haplotypes from the Iberian Peninsula, Anatolia with the Caucasus, and temperate Europe. The Iberian and the Anatolian branches represent parts of a major lineage that spans over the whole northern Mediterranean Basin and some neighbouring areas and probably dates back to the Tertiary. Many haplotypes of this lineage are distributed locally and most populations are fixed for a single haplotype; these populations have apparently been very stable since their establishment, experiencing negligible gene flow and few mutations. The temperate European lineage consists of one very widespread and abundant plus six locally distributed haplotypes. Four of them are located in Southeast Europe, the putative refugium of all extant temperate European populations. Contrary to populations from Iberia and Anatolia, F. alnus populations from the southeastern European refugium have most genetic variation within populations. Bird-mediated seed dispersal has apparently allowed not only a very rapid postglacial expansion of F. alnus but also subsequent regular seed exchanges between populations of the largely continuous species range in temperate Europe. In contrast, the disjunct F. alnus populations persisting in Mediterranean mountain ranges seem to have experienced little gene flow and have therefore accumulated a high degree of differentiation, even at short distances. Populations from the southern parts of the glacial refugia have contributed little to the postglacial recolonization of Europe, but their long-term historical continuity has allowed them to maintain a unique store of genetic variation.     

The genetic pattern of population threat and loss: a case study of butterflies

Recent decreases in biodiversity in Europe are commonly thought to be due to land use and climate change. However, the genetic diversity of populations is also seen as one essential factor for their fitness. Genetic diversity in species across the continent of Europe has been recognized as being in part a consequence of ice age isolation in southern refugia and postglacial colonization northwards, and these phylogeographical patterns may themselves affect the adaptability of populations. Recent work on butterfly species with different refugia, colonization paths and genetic structures allows this idea to be examined. The 'chalk-hill blue' pattern is one of decreasing genetic diversity from south to north, whereas the 'woodland ringlet' pattern shows greater genetic diversity in eastern than in western lineages. Comparison of population demographic trends in species with these biogeographical patterns reveals higher rates of decrease with lower genetic diversity. This indicates reduced adaptability due to genetic impoverishment as a result of glacial and postglacial range changes. Analysis of phylogeographical pattern may be a useful guide to interpreting demographic trends and in conservation planning.     

GM haplotype diversity of 82 populations over the world suggests a centrifugal model of human migrations

This study investigates the GM genetic relationships of 82 human populations, among which 10 represent original data, within and among the main broad geographic areas of the world. Different approaches are used: multidimensional scaling analysis and test for isolation by distance, to assess the correlation between genetic variation and spatial distributions; analysis of variance, to investigate the genetic structure at different hierarchical levels of population subdivision; genetic similarity map (geographic map distorted by available genetic information), to identify regions of high and low genetic variation; and minimal spanning network, to point out possible migration routes across continental areas. The results show that the GM polymorphism is characterized by one of the highest amounts of genetic variation observed so far among populations of different continents (Fct=0.3915, P < 0.0001). GM diversity can be explained by a model of isolation by distance (IBD) at most continental levels, with a particularly significant fit to IBD for the Middle East and Europe. Five peripheral regions of the world (Europe, west and south sub-Saharan Africa, Southeast Asia, and America) exhibit a low level of genetic diversity both within and among populations. By contrast, East and North African, Southwest Asian, and Northeast Asian populations are highly diverse and interconnected genetically by large genetic distances. Therefore, the observed GM variation can be explained by a "centrifugal model" of modern humans peopling history, involving ancient dispersals across a large intercontinental area spanning from East Africa to Northeast Asia, followed by recent migrations in peripheral geographic regions.     

Colonization of Northern Europe by Zygaena filipendulae (Lepidoptera)

Northern and mountainous ice sheets have expanded and contracted many times due to ice ages. Consequently, temperate species have been confined to refugia during the glacial periods wherefrom they have recolonized warming northern habitats between ice ages. In this study, we compare the gene CYP405A2 between different populations of the common burnet moth Zygaena filipendulae from across the Western Palearctic region to illuminate the colonization history of this species. These data show two major clusters of Z. filipendulae populations possibly reflecting two different refugial populations during the last ice age. The two types of Z. filipendulae only co‐occur in Denmark, Sweden, and Scotland indicating that Northern Europe comprise the hybridization zone where individuals from two different refugia met after the last ice age. Bayesian phylogeographic and ecological clustering analyses show that one cluster probably derives from an Alpe Maritime refugium in Southern France with ancestral expansive tendencies to the British Isles in the west, touching Northern Europe up to Denmark and Sweden, and extending throughout Central Europe into the Balkans, the Peleponnes, and South East Europe. The second cluster encompasses East Anatolia as the source area, from where multiple independent dispersal events to Armenia, to the Alborz mountains in north‐western Iran, and to the Zagros mountains in western Iran are suggested. Consequently, the classical theory of refugia for European temperate species in the Iberian, Italian, and Balkan peninsulas does not fit with the data from Z. filipendulae populations, which instead support more Northerly, mountainous refugia.     

Phylogeography of the barbel (Barbus barbus) assessed by mitochondrial DNA variation

Using the phylogeographic framework, we assessed the DNA sequence variation at the mitochondrial cytochrome b gene across the distribution range of the barbel Barbus barbus, a widely distributed European cyprinid. Reciprocal monophyly of non-Mediterranean European and Balkan/Anatolian populations is taken as evidence for a long-term barrier to gene flow, and interpreted as a consequence of survival of the species in two separate refugia during several later glacial cycles. Lack of profound genealogical divergence across Europe from western France to the northwestern Black Sea basin is consistent with recent colonization of this area from a single glacial refuge, which was probably located in the Danube River basin. This may have occurred in two steps: into the Western European river basins during the last interglacial, and throughout the Central European river basins after the last glacial. The populations from the Balkans and Anatolia apparently did not contribute mitochondrial DNA to the post-Pleistocene colonization of non-Mediterranean Europe. Lack of detectable variation within the Balkans/Anatolia is attributed mainly to recent expansion throughout these regions, facilitated by the freshwater conditions and seashore regression in the Black Sea during the Late Pleistocene and Early Holocene.     

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.     

Species distribution modeling and molecular markers suggest longitudinal range shifts and cryptic northern refugia of the typical calcareous grassland species Hippocrepis comosa (horseshoe vetch)

Calcareous grasslands belong to the most diverse, endangered habitats in Europe, but there is still insufficient information about the origin of the plant species related to these grasslands. In order to illuminate this question, we chose for our study the representative grassland species Hippocrepis comosa (Horseshoe vetch). Based on species distribution modeling and molecular markers, we identified the glacial refugia and the postglacial migration routes of the species to Central Europe. We clearly demonstrate that H. comosa followed a latitudinal and due to its oceanity also a longitudinal gradient during the last glacial maximum (LGM), restricting the species to southern refugia situated on the Peninsulas of Iberia, the Balkans, and Italy during the last glaciation. However, we also found evidence for cryptic northern refugia in the UK, the Alps, and Central Germany. Both species distribution modeling and molecular markers underline that refugia of temperate, oceanic species such as H. comosa must not be exclusively located in southern but also in western of parts of Europe. The analysis showed a distinct separation of the southern refugia into a western cluster embracing Iberia and an eastern group including the Balkans and Italy, which determined the postglacial recolonization of Central Europe. At the end of the LGM, H. comosa seems to have expanded from the Iberian refugium, to Central and Northern Europe, including the UK, Belgium, and Germany.     

Phylogeography and species limits in the green woodpecker complex (Aves: Picidae): multiple Pleistocene refugia and range expansion across Europe and the Near East

The green woodpecker complex consists of the green woodpecker (Picus viridis), distributed from Western Europe to the Caucasus and Iran, and the related LeVaillant's woodpecker (P. vaillantii), distributed in north‐western Africa from central Morocco to Tunisia. Much of the habitat of green woodpeckers in Central and Northern Europe was covered by ice, tundra, steppe or other unsuitable habitat during the Pleistocene; consequently, they must have come to occupy most of their current range during the past 20 000 years. We used complete mitochondrial ND2 sequences from populations throughout the range to investigate the genetic structure and evolutionary history of this complex. Three well‐differentiated clades, corresponding to three biogeographical regions, were recovered; 89% of the total genetic variance was distributed among these three regions. The populations in North Africa were sister to those of Europe and, within Europe, Iberia was sister to the rest of Europe and the Near East. This suggests that the post‐glacial colonization of most of Europe occurred from a refuge east of Iberia, probably in Italy or the Balkans; there was no substantial divergence among these regions. In addition, a population sample from Iran was genetically distinct from those of Western Europe, indicating a history of genetic isolation and an additional Pleistocene refuge east of the well‐known Balkan refugia and south of the Caucasus. Within Europe, northern populations were less genetically variable than southern ones, consistent with recent colonization. There was significant isolation‐by‐distance across Europe, indicating restricted gene flow; this was particularly apparent between western populations and those of the Caucasus and Iran. We recognize four species in the complex. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 710–723.     

Phylogeny and phylogeography of medicinal leeches (genus Hirudo): fast dispersal and shallow genetic structure

Medicinal leeches (Hirudo spp.) are among the best-studied invertebrates in many aspects of their biology. Yet, relatively little is known about their biogeography, ecology and evolution. Previous studies found vast ranges but suggested low genetic diversity for some species. To examine this apparent contradiction, the phylogeny and phylogeography of the widespread Hirudo verbana, Hirudo medicinalis and Hirudo orientalis were investigated in a comparative manner. Populations from across their ranges in Europe, Asia Minor, the Caucasus and Central Asia, were analyzed by various phylogenetic and population genetic approaches using both mitochondrial (COI and 12S) and nuclear DNA sequences (ITS1, 5.8S and ITS2). The populations showed surprisingly little genetic differentiation despite vast ranges. The only clear structure was observed in H. verbana. This species is subdivided into an Eastern (southern Ukraine, North Caucasus, Turkey and Uzbekistan) and a Western phylogroup (Balkans and Italy). The two phylogroups do not overlap, suggesting distinct postglacial colonization from separate refugia. Leeches supplied by commercial facilities belong to the Eastern phylogroup of H. verbana; they originate from Turkey and the Krasnodar Territory in Russia, two leading areas of leech export. H. verbana and H. medicinalis have experienced recent rapid population growth and range expansion, while isolation by distance has shaped the genetic setup of H. orientalis. The habitat of the latter is patchy and scattered about inhospitable arid and alpine areas of Central Asia and Transcaucasia. Centuries of leech collecting and transport across Europe seem not to have affected the natural distribution of genetic diversity, as the observed patterns can be explained by a combination of historical factors and present day climatic influences.     

Isolation by distance and gene flow in the Eurasian badger (Meles meles) at both a local and broad scale

Eurasian badgers, Meles meles, have been shown to possess limited genetic population structure within Europe; however, field studies have detected high levels of philopatry, which are expected to increase population structure. Population structure will be a consequence of both contemporary dispersal and historical processes, each of which is expected to be evident at a different scale. Therefore, to gain a greater understanding of gene flow in the badger, we examined microsatellite diversity both among and within badger populations, focusing on populations from the British Isles and western Europe. We found that while populations differed in their allelic diversity, the British Isles displayed a similar degree of diversity to the rest of western Europe. The lower genetic diversity occurring in Ireland, Norway and Scotland was more likely to have resulted from founder effects rather than contemporary population density. While there was significant population structure (F ST = 0.19), divergence among populations was generally well explained by geographic distance (P < 0.0001) across the entire range studied of more than 3000 km. Transient effects from the Pleistocene appear to have been replaced by a strong pattern of genetic isolation by distance across western Europe, suggestive of colonization from a single refugium. Analysis of individuals within British populations through Mantel tests and spatial autocorrelation demonstrated that there was significant local population structure across 3-30 km, confirming that dispersal is indeed restricted. The isolation by distance observed among badger populations across western Europe is likely to be a consequence of this restricted local dispersal.     

Mitochondrial and microsatellite DNA markers reveal a Balkan origin for the highly invasive horse-chestnut leaf miner Cameraria ohridella (Lepidoptera, Gracillariidae)

Biological invasions usually start with a small number of founder individuals. These founders are likely to represent a small fraction of the total genetic diversity found in the source population. Our study set out to trace genetically the geographical origin of the horse-chestnut leafminer, Cameraria ohridella , an invasive microlepidopteran whose area of origin is still unkown. Since its discovery in Macedonia 25 years ago, this insect has experienced an explosive westward range expansion, progressively colonizing all of Central and Western Europe. We used cytochrome oxidase I sequences (DNA barcode fragment) and a set of six polymorphic microsatellites to assess the genetic variability of C. ohridella populations, and to test the hypothesis that C. ohridella derives from the southern Balkans (Albania, Macedonia and Greece). Analysis of mtDNA of 486 individuals from 88 localities allowed us to identify 25 geographically structured haplotypes. In addition, 480 individuals from 16 populations from Europe and the southern Balkans were genotyped for 6 polymorphic microsatellite loci. High haplotype diversity and low measures of nucleotide diversities including a significantly negative Tajima's D indicate that C. ohridella has experienced rapid population expansion during its dispersal across Europe. Both mtDNA and microsatellites show a reduction in genetic diversity of C. ohridella populations sampled from artificial habitats (e.g. planted trees in public parks, gardens, along roads in urban or sub-urban areas) across Europe compared with C. ohridella sampled in natural stands of horse-chestnuts in the southern Balkans. These findings suggest that European populations of C. ohridella may indeed derive from the southern Balkans.     

Genetic consequences of glacial survival and postglacial colonization in Norway spruce: combined analysis of mitochondrial DNA and fossil pollen

Norway spruce (Picea abies [L.] Karst.) is a broadly distributed European conifer tree whose history has been intensively studied by means of fossil records to infer the location of full‐glacial refugia and the main routes of postglacial colonization. Here we use recently compiled fossil pollen data as a template to examine how past demographic events have influenced the species’ modern genetic diversity. Variation was assessed in the mitochondrial nad1 gene containing two minisatellite regions. Among the 369 populations (4876 trees) assayed, 28 mitochondrial variants were identified. The patterns of population subdivision superimposed on interpolated fossil pollen distributions indicate that survival in separate refugia and postglacial colonization has led to significant structuring of genetic variation in the southern range of the species. The populations in the northern range, on the other hand, showed a shallow genetic structure consistent with the fossil pollen data, suggesting that the vast northern range was colonized from a single refugium. Although the genetic diversity decreased away from the putative refugia, there were large differences between different colonization routes. In the Alps, the diversity decreased over short distances, probably as a result of population bottlenecks caused by the presence of competing tree species. In northern Europe, the diversity was maintained across large areas, corroborating fossil pollen data in suggesting that colonization took place at high population densities. The genetic diversity increased north of the Carpathians, probably as a result of admixture of expanding populations from two separate refugia.     

Phylogeography of the white-tailed eagle, a generalist with large dispersal capacity

Aim Late Pleistocene glacial changes had a major impact on many boreal and temperate taxa, and this impact can still be detected in the present‐day phylogeographic structure of these taxa. However, only minor effects are expected in species with generalist habitat requirements and high dispersal capability. One such species is the white‐tailed eagle, Haliaeetus albicilla, and we therefore tested for the expected weak population structure at a continental level in this species. This also allowed us to describe phylogeographic patterns, and to deduce Ice Age refugia and patterns of postglacial recolonization of Eurasia. Location Breeding populations from the easternmost Nearctic (Greenland) and across the Palaearctic (Iceland, continental Europe, central and eastern Asia, and Japan). Methods Sequencing of a 500 base‐pair fragment of the mitochondrial DNA control region in 237 samples from throughout the distribution range. Results Our analysis revealed pronounced phylogeographic structure. Overall, low genetic variability was observed across the entire range. Haplotypes clustered in two distinct haplogroups with a predominantly eastern or western distribution, and extensive overlap in Europe. These two major lineages diverged during the late Pleistocene. The eastern haplogroup showed a pattern of rapid population expansion and colonization of Eurasia around the end of the Pleistocene. The western haplogroup had lower diversity and was absent from the populations in eastern Asia. These results suggest survival during the last glaciation in two refugia, probably located in central and western Eurasia, followed by postglacial population expansion and admixture. Relatively high genetic diversity was observed in northern regions that were ice‐covered during the last glacial maximum. This, and phylogenetic relationships between haplotypes encountered in the north, indicates substantial population expansion at high latitudes. Areas of glacial meltwater runoff and proglacial lakes could have provided suitable habitats for such population growth. Main conclusions This study shows that glacial climate fluctuations had a substantial impact on white‐tailed eagles, both in terms of distribution and demography. These results suggest that even species with large dispersal capabilities and relatively broad habitat requirements were strongly affected by the Pleistocene climatic shifts.     

The colonization of Europe by the freshwater crustacean Asellus aquaticus (Crustacea: Isopoda) proceeded from ancient refugia and was directed by habitat connectivity

Recent continental-scale phylogeographic studies have demonstrated that not all freshwater fauna colonized Europe from the classic Mediterranean peninsular refugia, and that northern or central parts of the continent were occupied before, and remained inhabited throughout the Pleistocene. The colonization history of the ubiquitous aquatic isopod crustacean Asellus aquaticus was assessed using mitochondrial COI and a variable part of nuclear 28S rDNA sequences. Phylogeographic analysis of the former suggested that dispersion proceeded possibly during late Miocene from the western part of the Pannonian basin. Several areas colonized from here have served as secondary refugia and/or origins of dispersion, well before the beginning of the Pleistocene. Postglacial large-scale range expansion was coupled with numerous separate local dispersions from different refugial areas. Connectivity of the freshwater habitat has played an important role in shaping the current distribution of genetic diversity, which was highest in large rivers. The importance of hydrographic connections for the maintenance of genetic contact was underscored by a discordant pattern of mtDNA and nuclear rDNA differentiation. Individuals from all over Europe, differing in their mtDNA to a level normally found between species or even genera (maximal within population nucleotide divergence reached 0.16 +/- 0.018), shared the same 28S rRNA gene sequence. Only populations from hydrographically isolated karst water systems in the northwestern Dinaric Karst had distinct 28S sequences. Here isolation seemed to be strong enough to prevent homogenization of the rRNA gene family, whereas across the rest of Europe genetic contact was sufficient for concerted evolution to act.     

Genetic structure and colonization processes in European populations of the common vole, Microtus arvalis

The level of genetic differentiation within and between evolutionary lineages of the common vole (Microtus arvalis) in Europe was examined by analyzing mitochondrial sequences from the control region (mtDNA) and 12 nuclear microsatellite loci (nucDNA) for 338 voles from 18 populations. The distribution of evolutionary lineages and the affinity of populations to lineages were determined with additional sequence data from the mitochondrial cytochrome b gene. Our analyses demonstrated very high levels of differentiation between populations (overall FST: mtDNA 70%; nucDNA 17%). The affinity of populations to evolutionary lineages was strongly reflected in mtDNA but not in nucDNA variation. Patterns of genetic structure for both markers visualized in synthetic genetic maps suggest a postglacial range expansion of the species into the Alps, as well as a potentially more ancient colonization from the northeast to the southwest of Europe. This expansion is supported by estimates for the divergence times between evolutionary lineages and within the western European lineage, which predate the last glacial maximum (LGM). Furthermore, all measures of genetic diversity within populations increased significantly with longitude and showed a trend toward increase with latitude. We conclude that the detected patterns are difficult to explain only by range expansions from separate LGM refugia close to the Mediterranean. This suggests that some M. arvalis populations persisted during the LGM in suitable habitat further north and that the gradients in genetic diversity may represent traces of a more ancient colonization of Europe by the species.