Genetic divergence and phylogeographic relationships among european perch (Perca fluviatilis) populations reflect glacial refugia and postglacial colonization

We used the widely distributed freshwater fish, perch (Perca fluviatilis), to investigate the postglacial colonization routes of freshwater fishes in Europe. Genetic variability within and among drainages was assessed using mitochondrial DNA (mtDNA) D-loop sequencing and RAPD markers from 55 populations all over Europe as well as one Siberian population. High level of structuring for both markers was observed among drainages and regions, while little differentiation was seen within drainages and regions. Phylogeographic relationships among European perch were determined from the distribution of 35 mtDNA haplotypes detected in the samples. In addition to a distinct southern European group, which includes a Greek and a southern Danubian population, three major groups of perch are observed: the western European drainages, the eastern European drainages including the Siberian population, and Norwegian populations from northern Norway, and western side of Oslofjord. Our data suggest that present perch populations in western and northern Europe were colonized from three main refugia, located in southeastern, northeastern and western Europe. In support of this, nested cladistic analysis of mtDNA clade and nested clade distances suggested historical range expansion as the main factor determining geographical distribution of haplotypes. The Baltic Sea has been colonized from all three refugia, and northeastern Europe harbours descendants from both eastern European refugia. In the upper part of the Danube lineages from the western European and the southern European refugia meet. The southern European refugium probably did not contribute to the recolonization of other western and northern European drainages after the last glaciation. However, phylogenetic analyses suggest that the southern European mtDNA lineage is the most ancient, and therefore likely to be the founder of all present perch lineages. The colonization routes used by perch probably also apply to other freshwater species with similar distribution patterns.     

Genetic structure of Hypochaeris uniflora (Asteraceae) suggests vicariance in the Carpathians and rapid post-glacial colonization of the Alps from an eastern Alpine refugium

Aim The range of the subalpine species Hypochaeris uniflora covers the Alps, Carpathians and Sudetes Mountains. Whilst the genetic structure and post‐glacial history of many high‐mountain plant taxa of the Alps is relatively well documented, the Carpathian populations have often been neglected in phylogeographical studies. The aim of the present study is to compare the genetic variation of the species in two major European mountain systems – the Alps and the Carpathians. Location Alps and Carpathians. Methods The genetic variation of 77 populations, each consisting of three plants, was studied using amplified fragment length polymorphism (AFLP). Results Neighbour joining and principal coordinate analyses revealed three well‐supported phylogeographical groups of populations corresponding to three disjunct geographical regions – the Alps and the western and south‐eastern Carpathians. Moreover, two further clusters could be distinguished within the latter mountain range, one consisting of populations from the eastern Carpathians and the second consisting of populations from the southern Carpathians. Populations from the Apuseni Mountains had an intermediate position between the eastern and southern Carpathians. The genetic clustering of populations into four groups was also supported by an analysis of molecular variance, which showed that most genetic variation (almost 46%) was found among these four groups. By far the highest within‐population variation was found in the eastern Carpathians, followed by populations from the southern and western Carpathians. Generally, the populations from the Alps were considerably less variable and displayed substantially fewer region‐diagnostic markers than those from the south‐eastern Carpathians. Although no clear geographical structure was found within the Alps, based on neighbour joining or principal coordinate analyses, some trends were obvious: populations from the easternmost part were genetically more variable and, together with those from the south‐western part, exhibited a higher proportion of rare AFLP fragments than populations in other areas. Moreover, the total number of AFLP fragments per population, the percentage of polymorphic loci and the proportion of rare AFLP fragments significantly decreased from east to west. Main conclusions Deep infraspecific phylogeographical gaps between the populations from the Alps and the western and south‐eastern Carpathians suggest the survival of H. uniflora in three separate refugia during the last glaciation. Our AFLP data provide molecular evidence for a long‐term geographical disjunction between the eastern and western Carpathians, previously suggested from the floristic composition at the end of 19th century. It is likely that Alpine populations survived the Last Glacial in the eastern part of the Alps, from where they rapidly colonized the rest of the Alps after the ice sheet retreated. Multiple founder effects may explain a gradual loss of genetic variation during westward colonization of the Alps.     

Range-wide phylogeography of the European temperate-montane herbaceous plant Meum athamanticum Jacq.: evidence for periglacial persistence

Aim  The aim of this study is to analyse the genetic population structure of Meum athamanticum Jacq. in order to explore the alternative hypotheses (1) that the central and northern highland populations are the result of post-glacial recolonization from southern refugia, and the disjunct distribution of M. athamanticum can be explained by modern ecological conditions, or (2) that extant populations north of the Alps and Pyrenees persisted in situ during glacial periods.
Location  Europe.
Methods  Variation of amplified fragment length polymorphisms (AFLPs) was analysed for 23 populations from the entire range of the species. We used band-based approaches and methods based on allele frequencies to measure genetic diversity and to identify population structure.
Results  Our analyses reveal a north–south differentiation within M. athamanticum . High levels of genetic diversity, as well as private fragments, are found in populations both north and south of the Alps. Differentiation among populations is lower in the northern than in the southern population group, and significant isolation-by-distance is found only in the latter group.
Main conclusions  Our results indicate that M. athamanticum survived the last ice age in multiple refugia throughout its contemporary range and did not expand into areas north of the Alps from southern refugia. We found evidence that regional-scale migration in northern, formerly periglacial, parts of the species range has resulted in the intermingling of populations. In contrast, southern populations are characterized by long-term isolation. The south-west Alps represent an area where immigration and mixing of populations from northern and southern refugia appears to have taken place.     

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 a subalpine tall‐herb Ranunculus platanifolius (Ranunculaceae) reveals two main genetic lineages in the European mountains

A phylogeographical analysis of Ranunculus platanifolius, a typical European subalpine tall‐herb species, indicates the existence of two main genetic lineages based on amplified fragment length polymorphism (AFLP) markers. One group comprises populations from the Balkan Peninsula and the south‐eastern Carpathians and the other includes the remaining part of the range of the species, encompassing the western Carpathians, Sudetes, Alps, Pyrenees and Scandinavia. The main phylogeographical break observed in this species runs across the Carpathians and separates the main parts of this range (western and south‐eastern Carpathians), supporting a distinct glacial history of populations in these areas. The high genetic similarity of the Balkan Peninsula and south‐eastern Carpathian populations could indicate a common glacial refugium for these contemporarily isolated areas of species distribution. The western and northern part of the species range displays an additional weak differentiation into regional phylogeographical groups, which could have been shaped by isolation in glacial refugia or even by a postglacial isolation. The observed weak phylogeographical structure could also be linked with ecological requirements, allowing survival along streams in relatively low, forested mountain ranges. © 2013 The Linnean Society of London     

Phylogeography of Pulsatilla vernalis (L.) Mill. (Ranunculaceae): chloroplast DNA reveals two evolutionary lineages across central Europe and Scandinavia

Aim The aim of this study was to test hypotheses regarding some of the main phylogeographical patterns proposed for European plants, in particular the locations of glacial refugia, the post‐glacial colonization routes, and genetic affinities between southern (alpine) and northern (boreal) populations. Location The mountains of Europe (Alps, Balkans, Carpathians, Central Massif, Pyrenees, Scandinavian chain, Sudetes), and central European/southern Scandinavian lowlands. Methods As our model system we used Pulsatilla vernalis, a widely distributed European herbaceous plant occurring both in the high‐mountain environments of the Alps and other European ranges and in lowlands north of these ranges up to Scandinavia. Based on a distribution‐wide sampling of 61 populations, we estimated chloroplast DNA (cpDNA) variation along six regions using polymerase chain reaction–restriction fragment‐length polymorphisms (PCR–RFLPs) (trnH–trnK, trnK–trnK, trnC–trnD, psbC–trnS, psaA–trnS, trnL–trnF) and further sequencing of trnL–trnF and trnH–psbA. In addition, 11 samples of other European species of Pulsatilla were sequenced to survey the genus‐scale cpDNA variation. Results Eleven PCR–RFLP polymorphisms were detected in P. vernalis, revealing seven haplotypes. They formed two distinct genetic groups. Three haplotypes representing both groups dominated and were widely distributed across Europe, whereas the others were restricted to localized regions (central Alps, Tatras/Sudetes mountains) or single populations. Sequencing analysis confirmed the reliability of PCR–RFLPs and homology of haplotypes across their distribution. The chloroplast DNA variation across the section Pulsatilla was low, but P. vernalis did not share haplotypes with other species. Main conclusions The genetic distinctiveness of P. vernalis populations from the south‐western Alps with respect to other Alpine populations, as well as the affinities between the former populations and those from the eastern Pyrenees, is demonstrated, thus providing support for the conclusions of previous studies. Glacial refugia in the Dolomites are also suggested. Isolation is inferred for the high‐mountain populations from the Tatras and Sudetes; this is in contrast to the case for the Balkans, which harboured the common haplotype. Specific microsatellite variation indicates the occurrence of periglacial lowland refugia north of the Alps, acting as a source for the post‐glacial colonization of Scandinavia. The presence of different fixed haplotypes in eastern and western Scandinavia, however, suggests independent post‐glacial colonization of these two areas, with possible founder effects.     

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.     

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.     

The molecular population structure of the tall forb Cicerbita alpina (Asteraceae) supports the idea of cryptic glacial refugia in central Europe

There is an ongoing debate about the glacial history of non‐arctic species in central and northern Europe. The two main hypotheses are: (1) postglacial colonization from refugia outside this region; (2) glacial survival in microclimatically favourable sites within the periglacial areas. In order to clarify the glacial history of a boreo‐montane tall forb, we analysed AFLPs from populations of Cicerbita alpina through most of its range (Scandinavia, the mountains of central Europe, the Alps, the Pyrenees and the Balkan Peninsula). We found a major differentiation between the Pyrenean population and all others, supported by principal coordinate, neighbour joining and STRUCTURE analyses. Furthermore, three populations from the central and north‐eastern Alps were genetically distinct from the bulk of populations from Scandinavia, central Europe, the Alps and the Balkan Peninsula. Most populations, including those from central and northern Europe, had moderate to high levels of genetic diversity (mean Shannon index H_Sh = 0.292, mean percentage of polymorphic loci P = 54.1%, mean Nei's gene diversity H = 0.195). The results indicate separate glacial refugia in the Pyrenean region and the Italian Alps. Furthermore, they provide evidence of glacial persistence in cryptic refugia north of the Alps, from where Scandinavia and most of the Alps are likely to have been colonized following deglaciation. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 142–154.     

Glacial refugia and postglacial expansion of the alpine–prealpine plant species Polygala chamaebuxus

The shrubby milkwort (Polygala chamaebuxus L.) is widely distributed in the Alps, but occurs also in the lower mountain ranges of Central Europe such as the Franconian Jura or the Bohemian uplands. Populations in these regions may either originate from glacial survival or from postglacial recolonization. In this study, we analyzed 30 populations of P. chamaebuxus from the whole distribution range using AFLP (Amplified Fragment Length Polymorphism) analysis to identify glacial refugia and to illuminate the origin of P. chamaebuxus in the lower mountain ranges of Central Europe. Genetic variation and the number of rare fragments within populations were highest in populations from the central part of the distribution range, especially in the Southern Alps (from the Tessin Alps and the Prealps of Lugano to the Triglav Massiv) and in the middle part of the northern Alps. These regions may have served, in accordance with previous studies, as long‐term refugia for the glacial survival of the species. The geographic pattern of genetic variation, as revealed by analysis of molecular variance, Bayesian cluster analysis and a PopGraph genetic network was, however, only weak. Instead of postglacial recolonization from only few long‐term refugia, which would have resulted in deeper genetic splits within the data set, broad waves of postglacial expansion from several short‐term isolated populations in the center to the actual periphery of the distribution range seem to be the scenario explaining the observed pattern of genetic variation most likely. The populations from the lower mountain ranges in Central Europe were more closely related to the populations from the southwestern and northern than from the nearby eastern Alps. Although glacial survival in the Bohemian uplands cannot fully be excluded, P. chamaebuxus seems to have immigrated postglacially from the southwestern or central‐northern parts of the Alps into these regions during the expansion of the pine forests in the early Holocene.     

Phylogeography and Pleistocene refugia of the Little Owl Athene noctua inferred from mtDNA sequence data

Pleistocene glaciations greatly affected the distribution of genetic diversity in animal populations. The Little Owl is widely distributed in temperate regions and could have survived the last glaciations in southern refugia. To describe the phylogeographical structure of European populations, we sequenced the mitochondrial cytochrome c oxidase I (COI) and control region (CR1) in 326 individuals sampled from 22 locations. Phylogenetic analyses of COI identified two deeply divergent clades: a western haplogroup distributed in western and northwestern Europe, and an eastern haplogroup distributed in southeastern Europe. Faster evolving CR1 sequences supported the divergence between these two main clades, and identified three subgroups within the eastern clade: Balkan, southern Italian and Sardinian. Divergence times estimated from COI with fossil calibrations indicate that the western and eastern haplogroups split 2.01–1.71 Mya. Slightly different times for splits were found using the standard 2% rate and 7.3% mtDNA neutral substitution rate. CR1 sequences dated the origin of endemic Sardinian haplotypes at 1.04–0.26 Mya and the split between southern Italian and Balkan haplogroups at 0.72–0.21 Mya, coincident with the onset of two Pleistocene glaciations. Admixture of mtDNA haplotypes was detected in northern Italy and in central Europe. These findings support a model of southern Mediterranean and Balkan refugia, with postglacial expansion and secondary contacts for Little Owl populations. Central and northern Europe was predominantly recolonized by Little Owls from Iberia, whereas expansion out of the Balkans was more limited. Northward expansion of the Italian haplogroup was probably prevented by the Alps, and the Sardinian haplotypes remained confined to the island. Results showed a clear genetic pattern differentiating putative subspecies. Genetic distances between haplogroups were comparable with those recorded between different avian species.     

Population genomic evidence for plant glacial survival in Scandinavia

Quaternary glaciations have played a major role in shaping the genetic diversity and distribution of plant species. Strong palaeoecological and genetic evidence supports a postglacial recolonization of most plant species to northern Europe from southern, eastern and even western glacial refugia. Although highly controversial, the existence of small in situ glacial refugia in northern Europe has recently gained molecular support. We used genomic analyses to examine the phylogeography of a species that is critical in this debate. Carex scirpoidea Michx subsp. scirpoidea is a dioecious, amphi‐Atlantic arctic–alpine sedge that is widely distributed in North America, but absent from most of Eurasia, apart from three extremely disjunct populations in Norway, all well within the limits of the Weichselian ice sheet. Range‐wide population sampling and variation at 5,307 single nucleotide polymorphisms show that the three Norwegian populations comprise unique evolutionary lineages divergent from Greenland with high between‐population divergence. The Norwegian populations have low within‐population genetic diversity consistent with having experienced genetic bottlenecks in glacial refugia, and host private alleles that probably accumulated in long‐term isolated populations. Demographic analyses support a single, pre‐Weichselian colonization into Norway from East Greenland, and subsequent divergence of the three populations in separate refugia. Other refugial areas are identified in North‐east Greenland, Minnesota/Michigan, Colorado and Alaska. Admixed populations in British Columbia and West Greenland indicate postglacial contact. Taken together, evidence from this study strongly indicates in situ glacial survival in Scandinavia.     

Genetic diversity and phylogeography of the European roe deer: the refuge area theory revisited

The extant taxa of central and northern Europe are commonly believed to derive from Pleistocene ancestors, who moved to the north from three separate glacial refugia: the Iberian and Italian peninsulae, as well as the southern Balkans. The issue of postglacial dispersal patterns was addressed through the investigation of population structure and phylogeography of the European roe deer, Capreolus capreolus . The genetic diversity in 376 individuals representing 14 allegedly native populations across their European range was assessed, using ten autosomal microsatellite loci and restriction fragment length polymorphisms of the mitochondrial D-loop and NADH dehydrogenase 1 gene segments. Our results suggest the existence of three major genetic lineages of roe deer in Europe. One comprises populations in the south-western limit of the species' distribution (i.e. Iberia), where an internal substructure splits a northern from a southern sublineage. A second lineage includes populations of southern and eastern Europe, as well as a separate sublineage sampled in central-southern Italy, where the existence of the subspecies Capreolus c. italicus was supported. In central-northern Europe, a third lineage is present, which appeared genetically rather homogeneous, although admixed, and equally divergent from both the eastern and western lineages. Current patterns of intraspecific genetic variation suggest that postglacial recolonization routes of this cervid to northern Europe could be due to range expansion from one or more refugia in central-eastern Europe, rather than proceeding from the Mediterranean areas.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 85–100.     

Cytotype distribution and phylogeography of Hieracium intybaceum (Asteraceae)

Using flow cytometry and amplified fragment length polymorphism (AFLP), we explored the cytogeography and phylogeography of Hieracium intybaceum, a silicicolous species distributed in the Alps and spatially isolated in the Vosges Mountains and the Schwarzwald Mountains. We detected two ploidies, diploid and tetraploid, but no triploid or mixed‐ploidy populations. Whereas diploids are sexual and distributed all across the Alps, tetraploids are apomictic and seem to be confined to the western Alps and the Vosges. We detected a low level of genetic variation. Bayesian clustering identified four clusters/genetic groups, which are partly congruent with the ploidal pattern. The first two groups consisting exclusively of diploids dominate the whole distribution range in the Alps and show east–west geographical separation with a diffuse borderline running from eastern Switzerland to the eastern part of North Tyrol. The third genetic group lacks a defined geographical range and includes diploid and tetraploid plants. The last genetic group comprises tetraploid plants in the French Alps and the Vosges. We suppose that diploids colonized the deglaciated areas from source populations most likely located mainly in the southern part of the recent distribution range and occasionally also in the western Alps. Gene flow and further differentiation likely took place. Apomictic tetraploids most likely originated in the western Alps or in the refugium at the south‐western foot of the Alps. Their rather limited geographical range (partly contrasting with the theory of geographical parthenogenesis) can be explained by their rather recent origin. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 487–498.     

Dynamics in the evolution of sexual traits: losses and gains,radiation and convergence in yellow wagtails (Motacilla flava)

We analyse patterns of genetic diversity and song complexity in the Palaearctic yellow wagtail (Motacilla flava), a highly polytypic species complex. Mitochondrial and nuclear DNA show that the complex is polyphyletic, despite parallel plumage variation in western and eastern clades. In the western clade there is genetic structure among southern subspecies, haplotype diversity decreases with latitude, and northern subspecies show evidence of bottlenecking and rapid expansions, as expected from isolation in glacial refugia followed by postglacial colonization. However, northern subspecies, which have more divergent male plumages, lack genetic structure and sing simpler songs. Loss of song complexity and evolution of plumage in founder populations are consistent with the Kaneshiro model, which posits that variation among species is a consequence of founder-induced shifts in female preference leading to loss of ancestral male sexual traits. Our results suggest possible postglacial founder-effect mechanisms for the morhological diversification of the yellow wagtail complex.     

Identification of glacial refugia in south-eastern North America by phylogeographical analyses of a forest understorey plant, Trillium cuneatum

Aim We examine several hypotheses emerging from biogeographical and fossil records regarding glacial refugia of a southern thermophilic plant species. Specifically, we investigated the glacial history and post‐glacial colonization of a forest understorey species, Trillium cuneatum. We focused on the following questions: (1) Did T. cuneatum survive the Last Glacial Maximum (LGM) in multiple refugia, and (if so) where were they located, and is the modern genetic structure congruent with the fossil record‐based reconstruction of refugia for mesic deciduous forests? (2) What are the post‐glacial colonization patterns in the present geographical range? Location South‐eastern North America. Methods We sampled 45 populations of T. cuneatum throughout its current range. We conducted phylogeographical analyses based on maternally inherited chloroplast DNA (cpDNA haplotypes) and used TCS software to reconstruct intraspecific phylogeny. Results We detected six cpDNA haplotypes, geographically highly structured into non‐overlapping areas. With one exception, none of the populations had mixed haplotype composition. TCS analysis resulted in two intraspecific cpDNA lineages, with one clade subdivided further by shallower diversification. Main conclusions Our investigation revealed that T. cuneatum survived the LGM in multiple refugia, belonging to two (western, eastern) genealogical lineages geographically structured across south‐eastern North America. The western clade is confined to the south‐western corner of T. cuneatum’s modern range along the Lower Mississippi Valley, where fossil records document a major refugium of mesic deciduous forest. For the eastern clade, modern patterns of cpDNA haplotype distribution suggest cryptic vicariance, in the form of forest contractions and subsequent expansions associated with Pleistocene glacial cycles, rather than simple southern survival and subsequent northward colonization. The north–south partitioning of cpDNA haplotypes was unexpected, suggesting that populations of this rather southern thermophilic species may have survived in more northern locations than initially expected based on LGM climate reconstruction, and that the Appalachian Mountains functioned as a barrier to the dispersal of propagules originating in more southern refugia. Furthermore, our results reveal south‐west to north‐east directionality in historical migration through the Valley and Ridge region of north‐west Georgia.     

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.     

Vegetation history of Abies alba Mill. (silver fir) in Switzerland – pollen analytical and genetic surveys related to aspects of vegetation history of Picea abies (L.) H. Karsten (Norway spruce)

This contribution deals with some new aspects of the relationship between the vegetation history of Abies alba Mill. (silver fir) and genetic studies of this tree species in Switzerland. The results of the present study confirm the pollen analytical hypothesis that A. alba re-immigrated into Switzerland mainly from glacial refugia located in northern and central Italy. In particular, some distinct immigration routes of silver fir into the Ticino Alps, Valais, the Bernese Oberland (northwestern Alps), and Graubünden (eastern Alps) could be confirmed by genetic studies. Furthermore, the occurrence of other area-specific alleles indicates an additional influence from eastern European refugia on the Swiss gene pool. Moreover, genetic studies on Picea abies (L.) H. Karsten (Norway spruce) confirmed the general immigration routes from the eastern to the western Alps and from Savoie to the Jura Mountains. The combination of tree pollen and macrofossil analyses of Quaternary sediments with genetic studies of the same tree species represents a considerable research potential and is a new approach of floristic and genetic research. Received November 17, 2000 / Accepted April 27, 2001     

Southern isolation and northern long‐distance dispersal shaped the phylogeography of the widespread,but highly disjunct,European high mountain plant Artemisia eriantha (Asteraceae)

We investigated the range dynamics of Artemisia eriantha, a widespread, but rare, mountain plant with a highly disjunct distribution in the European Alpine System. We focused on testing the roles of vicariance and long‐distance dispersal in shaping the current distribution of the species. To this end, we collected AFLP and plastid DNA sequence data for 17 populations covering the entire distributional range of the species. Strong phylogeographical structure was found in both datasets. AFLP data suggested that almost all populations were genetically strongly differentiated, with 58% of the overall genetic variation partitioned among populations. Bayesian clustering identified five groups of populations: Balkans, Pyrenees, Central Apennines, one southwestern Alpine population and a Widespread cluster (eastern Pyrenees, Alps, Carpathians). Major groups were supported by neighbor‐joining and NeighbourNet analyses. Fourteen plastid haplotypes were found constituting five strongly distinct lineages: Alps plus Pyrenees, Apennines, Balkans, southern Carpathians, and a Widespread group (eastern Pyrenees, northern Carpathians, Mt. Olympus). Plastid DNA data suggested that A. eriantha colonized the European Alpine System in a westward direction. Although, in southern Europe, vicariant differentiation among the Iberian, Italian and Balkan Peninsulas predominated, thus highlighting their importance as glacial refugia for alpine species, in temperate mountain ranges, long‐distance dispersal prevailed. This study emphasizes that currently highly disjunct distributions can be shaped by both vicariance and long‐distance dispersal, although their relative importance may be geographically structured along, for instance, latitude, as in A. eriantha. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174 , 214–226.