Multiple cryptic refugia of forest grass Bromus benekenii in Europe as revealed by ISSR fingerprinting and species distribution modelling

Despite not having been fully recognized, the cryptic northern refugia of temperate forest vegetation in Central and Western Europe are one of the most important in the Holocene history of the vegetation on the subcontinent. We have studied a forest grass Bromus benekenii in 39 populations in Central, Western and Southern Europe with the use of PCR-ISSR fingerprinting. The indices of genetic population diversity, multivariate, and Bayesian analyses, supplemented with species distribution modelling have enabled at least three putative cryptic northern refugial areas to be recognized: in Western Europe—the Central and Rhenish Massifs, in Central Europe—the Bohemia–Moravia region and in the Eastern/Western Carpathians. Central Poland is the regional genetic melting-pot where several migratory routes might have met. Southern Poland had a different postglacial history and was under the influence of an Eastern/Western Carpathian cryptic refugium. More forest species should be checked in a west–east gradient in Europe to corroborate the hypothesis on the Western European glacial refugia.     

Evolutionary processes,dispersal limitation and climatic history shape current diversity patterns of European dragonflies

We investigated the effects of contemporary and historical factors on the spatial variation of European dragonfly diversity. Specifically, we tested to what extent patterns of endemism and phylogenetic diversity of European dragonfly assemblages are structured by 1) phylogenetic conservatism of thermal adaptations and 2) differences in the ability of post‐glacial recolonization by species adapted to running waters (lotic) and still waters (lentic). We investigated patterns of dragonfly diversity using digital distribution maps and a phylogeny of 122 European dragonfly species, which we constructed by combining taxonomic and molecular data. We calculated total taxonomic distinctiveness and mean pairwise distances across 4192 50 × 50 km equal‐area grid cells as measures of phylogenetic diversity. We compared species richness with corrected weighted endemism and standardized effect sizes of mean pairwise distances or residuals of total taxonomic distinctiveness to identify areas with higher or lower phylogenetic diversity than expected by chance. Broken‐line regression was used to detect breakpoints in diversity–latitude relationships. Dragonfly species richness peaked in central Europe, whereas endemism and phylogenetic diversity decreased from warm areas in the south‐west to cold areas in the north‐east and with an increasing proportion of lentic species. Except for species richness, all measures of diversity were consistently higher in formerly unglaciated areas south of the 0°C isotherm during the Last Glacial Maximum than in formerly glaciated areas. These results indicate that the distributions of dragonfly species in Europe were shaped by both phylogenetic conservatism of thermal adaptations and differences between lentic and lotic species in the ability of post‐glacial recolonization/dispersal in concert with the climatic history of the continent. The complex diversity patterns of European dragonflies provide an example of how integrating climatic and evolutionary history with contemporary ecological data can improve our understanding of the processes driving the geographical variation of biological diversity.     

Higher genetic diversity in recolonized areas than in refugia of Alnus glutinosa triggered by continent‐wide lineage admixture

Genetic admixture is supposed to be an important trigger of species expansions because it can create the potential for selection of genotypes suitable for new climatic conditions. Up until now, however, no continent‐wide population genetic study has performed a detailed reconstruction of admixture events during natural species expansions. To fill this gap, we analysed the postglacial history of Alnus glutinosa, a keystone species of European swamp habitats, across its entire distribution range using two molecular markers, cpDNA and nuclear microsatellites. CpDNA revealed multiple southern refugia located in the Iberian, Apennine, Balkan and Anatolian Peninsulas, Corsica and North Africa. Analysis of microsatellites variation revealed three main directions of postglacial expansion: (i) from the northern part of the Iberian Peninsula to Western and Central Europe and subsequently to the British Isles, (ii) from the Apennine Peninsula to the Alps and (iii) from the eastern part of the Balkan Peninsula to the Carpathians followed by expansion towards the Northern European plains. This challenges the classical paradigm that most European populations originated from refugial areas in the Carpathians. It has been shown that colonizing lineages have met several times and formed secondary contact zones with unexpectedly high population genetic diversity in Central Europe and Scandinavia. On the contrary, limited genetic admixture in southern refugial areas of A. glutinosa renders rear‐edge populations in the Mediterranean region more vulnerable to extinction due to climate change.     

Adaptations of dragonflies (Odonata) under desert conditions

Different types of adaptations of dragonflies to climatic conditions of the desert zone are described. The main habitats of the dragonfly nymphs are lotic and semi-lotic artificial reservoirs. The life cycles are synchronous with seasonal climatic changes, reproduction being restricted to periods of the optimal hygrothermal conditions. Some species reveal vertical seasonal migrations. The labile daily activity rhythms allow the dragonflies to avoid the effects of unfavorable conditions. Adults of many species emerge at night.     

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.     

Simple pond restoration measures increase dragonfly (Insecta: Odonata) diversity

Ponds are home to a diverse community of specialized plants and animals and are hence of great conservation concern. Through land-use changes, ponds have been disappearing rapidly and remaining ponds are often threatened by contamination and eutrophication, with negative consequences for pond-dependent taxa like amphibians or dragonflies (Odonata: Anisoptera and Zygoptera). Increasingly, restoration measures such as removal of shading terrestrial vegetation or submerged organic matter are implemented to counteract current threats, but how these measures affect the target taxa is rarely assessed. We tested if and how simple pond restoration measures affectionate diversity. We propose that pond restoration influences the light regime, which promotes aquatic and riparian vegetation important for different dragonfly life stages, thus increasing their diversity. Additionally, we assume that this changes dragonfly species composition between restored and unrestored ponds. We surveyed exuviae in the riparian and aquatic vegetation along the shore of 29 (12 restored, 17 unrestored) man-made ponds in southwest Germany and assessed environmental variables known to affect dragonfly diversity. We identified the cover of tall sedges and submerged macrophytes as the driving biotic variables for dragonfly diversity and species composition, with restoration measures affecting submerged macrophyte cover directly but tall sedges indirectly via available sunlight. This study demonstrates that simple restoration measures not only have a positive effect on overall dragonfly diversity, but also increase habitat suitability for several species that would otherwise be absent. We therefore propose dragonflies as a suitable flagship group for pond conservation.     

Distribution patterns of dragonflies (Odonata) in Central Asia

The dragonfly fauna of Central Asia reveals distinct vertical differentiation. Three groups of species can be distinguished: mountain (24 species), plain (18), and plain-mountain (34) ones. The ranges observed can be classified into 7 principal types: plain, mountain, continuous boreo-montane, disjunctive Central Asian boreomontane, disjunctive Tien Shan boreo-montane, Central Asian, and Pamir-Alay plain-mountain. The leading factors determining the distribution of dragonflies are the temperature and the presence of streams suitable for preimaginal development; the former factor determines the potential ranges, and the latter, the actual ones. The present-day composition, structure, and vertical distribution of the dragonfly fauna formed during the historical time, after the development of artificial irrigation canals which provided new habitats for dragonflies.     

Phylogeography of European moose (Alces alces) based on contemporary mtDNA data and archaeological records

Phylogeography can help to determine LGM refugia and postglacial migration routes. However, the locations of LGM refugial areas in eastern Europe are not clear. Moose (Alces alces) is presently a common species in central and north-eastern Europe, but there are no studies showing its phylogenetic pattern and genetic diversity across its whole continuous range. Moose never became extinct in the eastern part of its range, and the eastern mtDNA lineage has the largest effective population size. The present study shows the phylogeographic pattern and genetic diversity of European moose and compares the results of mtDNA analyses with the archaeological record of the species to identify its LGM refugia and postglacial migration routes. I combined the mtDNA control region sequences obtained in all studies of moose in Europe and western Asia. The genetic data were then compared with the archaeological records of the species dated to the LGM. I found that the European moose lineage inhabits Europe and western Asia. It is composed of two clades: the eastern and the central-western, consisting of a total of six discrete haplogroups. The most complex, the eastern clade, has the largest range. Some of the haplogroups have narrow or scattered distributions and two are common in almost the whole range. Genetic diversity hotspots were detected in contact zones of different mtDNA haplogroups rather than in the LGM refugial areas of moose. Archaeological records dated to the LGM were found in several localities in central, southern and eastern Europe as well as in western Asia. The range of the moose during the LGM was much larger than previously thought. The eastern clade survived the LGM in western Siberia, the Ural Mountains and Russian plain. LGM refugia of moose were also located in the Caucasus, Carpathians, Balkans and northern Italy.     

Ice-age isolation,postglacial hybridization and recent population bottlenecks shape the genetic structure of Meum athamanticum in Central Europe

Phylogeographic analyses can help to reveal the refugial structure of plants during and after the ice ages, but the detailed history of regional refugial isolation and differentiation in Central Europe is still poorly understood. A recent study of Meum athamanticum in its total range of occurrences revealed persistence of this temperate montane plant species in Central Europe north of the Alps, without going into details. We therefore aimed to study differentiation and migration processes of this plant species in more detail throughout Central Europe. We used high resolution amplified fragment length polymorphisms (AFLP) markers and analyzed 210 plant individuals of 14 Central European populations with three pairs of primer combinations (128 loci, 111 of which polymorphic). The data show genetic differentiation and varying levels of molecular diversity within populations and groups of populations. Altogether, the studied populations did not show a gradient in molecular variation along presumptive postglacial migration routes across Central Europe. Rather, they reveal a genetic division into seven major groups. Four of them are characterised by high genetic diversity, private fragments and higher than average number of rare and sparse fragments, leading to the assumption that they are descendants of independent populations which survived in glacial refugia. In combination with information from paleoclimate and paleovegetation, it is likely that microclimatically favoured habitats at (i) the eastern flank of the Black Forest, (ii) the southern margin of the Cologne basin, (iii) the foothills of the Erzgebirge, and (iv) the foothills of the Jura Mountains acted as sources for the postglacial recolonisation of this species to the other mountains of Central Europe. As some of the populations analysed show intermixed gene-pools (i.e. including genetic information from different groups) and partly have exceptionally high genetic diversity, but no private and only relatively few rare or sparse fragments, they might represent contact zones. On the other hand, genetic pauperization and isolation of two other populations in connection with extremely small population sizes and unfavourable habitat conditions seem to reflect recent bottlenecks. Consequently, the genetic structure of M. athamanticum in Central Europe is shaped by (i) extra-Mediterranean glacial refugia in situ, (ii) following postglacial hybridization along emerging contact zones and (iii) genetic bottlenecks in thereafter isolated small populations. All results provide evidences for small scale migration of the species between Central European valleys and surrounding highlands. Therefore, our study provides molecular evidence for both climate dependent wide ranging periglacial tabula rasa, but some small refugia in locally buffered areas. We hereby show that the environmental heterogeneity of cold stage landscapes in Central Europe is generally underestimated.     

Potential source and sink locations for climate‐driven species range shifts in Europe since the Last Glacial Maximum

Aim To identify potential source and sink locations for climate‐driven species range shifts in Europe since the Last Glacial Maximum (LGM). Location Europe. Methods We developed a new approach combining past‐climate simulations with the concept of analogous climate space. Our index gives a continuous measure of the potential of a location to have acted as a source or a sink for species that have shifted their ranges since the LGM. High glacial source potential is indicated by LGM climatic conditions that are widespread now; high post‐glacial sink potential is indicated by current climatic conditions that were widespread at the LGM. The degree of isolation of source and sink areas was calculated as the median distance to areas with analogous climate conditions. Results We identified areas of high glacial source potential in the previously recognized refugial areas in the southern European peninsulas, but also in large areas in central‐western Europe. The most climatically isolated source areas were located in northern Spain, in north‐western Europe and in eastern Turkey. From here species would have had to cover substantial distances to find current climate conditions analogous to LGM conditions of these areas. Areas with high post‐glacial sink potential were mainly located in Fennoscandia and in central and south‐eastern Europe. Some of the most isolated sink areas were located in the Spanish highlands and around the Baltic Sea. Main conclusions Our species‐independent approach successfully identified previously recognized glacial refugial areas with high source potential for species range shifts in southern Europe and in addition highlighted other potential source areas in central Europe. This study offers new insights into how the distribution of past and current climatic conditions may have influenced past species range shifts and current large‐scale biodiversity patterns.     

Chloroplast DNA phylogeography of Alnus glutinosa (L.) Gaertn.

Traditionally, information on the postglacial history of plant species has been gained from the analysis of fossil pollen data. More recently, surveys of present patterns of genetic variation have given valuable insights into species phylogeography. The genus Alnus , based on fossil data, is known to have had at least four glacial refugia. A survey of chloroplast DNA (cpDNA) diversity in populations of black alder ( A. glutinosa ) was undertaken in order to gain more insight into its postglacial history. This revealed a high degree of structuring of 13 cpDNA haplotypes on a European scale which indicated that most of northern and central Europe was colonized from a refuge in the Carpathian Mountains. Based on the distribution of two common cpDNA haplotypes, colonization routes from this refuge can be determined. The locations of other previously identified refugia are confirmed and two formerly unconfirmed refugial areas for alder (southern Spain and Turkey) are proposed.     

Migrations of dragonflies (Odonata) in the south of the West Siberian plain

The paper presents a summary of mass dragonfly migrations observed previously in Russia, in particular in West Siberia. From 1969 to 2009, the authors studied the dynamics of dragonfly population, their spatial distribution and movements in the West Siberian forest-steppe. The main studies were conducted in the Lake Chany basin (the Biological Station of the Institute of Animal Systematics and Ecology, Siberian Division, Russian Academy of Sciences). The spatial redistribution of dragonflies is regarded as a balance of homing and wandering behavior. Homing results in a relative stability of local dragonfly populations and assemblages, while wandering leads to dispersal of dragonflies from their emergence sites and colonization of new habitats; the latter is especially important due to the ephemeral nature of many shallow reservoirs where the nymphs develop. The formation of more or less constant migration routes is a peculiar variant of wandering activities. A special type of dragonfly migrations is mass exodus from native habitats, triggered by excessive population growth and leading to elimination of all or most individuals. Such migrations not only optimize the size of dragonfly populations but also facilitate removal of nutrients and organic matter from eutrophic water bodies. An original generalized classification of dragonfly migrations is proposed.     

The Australian monsoon tropics as a barrier for exchange of dragonflies (Insecta: Odonata) between New Guinea and Australia

Recent studies show a remarkable scarcity of faunal exchange events between Australia and New Guinea in the Pleistocene despite the presence of a broad land connection for long periods. This is attributed to unfavourable conditions in the connecting area associated with the long established northern Australian Monsoon Climate. This would be expected to have impacted strongly on freshwater faunas with the following results: (1) limited overlap in species, (2) most higher taxonomic groups present in both areas sharing no species or even genera and (3) shared species dominated by lentic species with high dispersal capacity. Testing these predictions for dragonflies showed the turnover in the family, genus and species composition between Australia and New Guinea to be higher than anywhere in the world with only 50% of families and subfamilies, 33% of the genera and 8% of the species being shared. Only one of the 53 shared species favors lotic waters compared with 64% of the 652 combined Australian–New Guinean species. These results agree with our predictions and indicate that the dragonfly fauna of Australia and New Guinea have effectively been separated during the Pleistocene probably due to the prolonged unfavourable climatic conditions in the intervening areas.     

Einwanderungsrouten nach Mitteleuropa

Butterflies – who is coming, who is going? Immigration routes to Central Europe The majority of butterflies and burnet moths distributed in Central Europe today results from postglacial colonisation of this region mostly from expansions out of the well known Mediterranean refuge areas. The study region was mostly colonised west or east of the Alps, which represent a strong dispersal obstacle. Species being widespread under glacial conditions in Central Europe have retreated under the warm conditions of the Postglacial to the high mountain systems or the Arctic. Therefore, they are mostly restricted to the high altitudes of the Alps in Western Central Europe. Nevertheless, some species have even survived in lowland areas of Central Europe during glacial and inter‐/postglacial conditions, but these species are either better adapted to glacial or to inter‐/postglacial conditions.     

The impacts of habitat disturbance on adult and larval dragonflies (Odonata) in rainforest streams in Sabah,Malaysian Borneo

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Phylogeography of the burnet moth Zygaena transalpina complex: molecular and morphometric differentiation suggests glacial refugia in Southern France,Western France and micro‐refugia within the Alps

Patterns of common recolonization routes from glacial refugia to Central Europe during the Pleistocene are generalized to paradigms of postglacial recolonization in Europe. Recent studies indicate, however, that the actual phylogeographic history of many species might be more complex and cannot be simplified to generalized patterns. Burnet moths of the Zygaena transalpina complex represent a group of closely related taxa, which are considered as a typical example for these generalized patterns. At present, three groups are recognized that are assumed to have spread from three classical refugia in Western Europe, Italy and the Balkans to Central Europe. Here, we re‐investigate their phylogeography using a combined molecular and morphometric approach. Phylogenetic and nested clade phylogeographic analyses of 476 samples from 55 localities taken from Southern and Central Europe reveal that the Zygaena transalpina complex consists of three distinct haplotype clusters, which geographically roughly correspond to possible refugia in Western Europe, Italy and the Balkans. A synthesis of the data with a geometric morphometry dataset of 425 specimens from 46 localities corroborates this molecular result but differs in several aspects. Important new aspects are multiple refugia of the western ‘hippocrepidis’ branch and micro‐habitats within the Alps of the central ‘transalpina’ branch. Further, our results display a more complex phylogeographic pattern for this species complex, which is not tractable with a rigid, generalized pattern.     

Geographically congruent large‐scale patterns of plastid haplotype variation in the European herbs Silene dioica and S. latifolia (Caryophyllaceae)

The closely related dioecious herbs Silene latifolia and Silene dioica are widespread and predominantly sympatric in Europe. The species are interfertile, but morphologically and ecologically distinct. A study of large‐scale patterns of plastid DNA (polymerase chain reaction–restriction fragment length polymorphism) haplotypes in a sample of 198 populations from most of the European ranges of both species revealed extensive interspecific haplotype sharing. Four of the 28 detected haplotypes were frequent (found in > 40 populations) and widespread. Three of these frequent haplotypes occurred in both species and the geographic distribution of each haplotype was broadly congruent in both species. Each of these three, shared and widespread haplotypes is likely to have colonized central and/or northern Europe after the last glaciation from one or more of refugial areas in southern Europe. Interspecific hybridization and plastid introgression within refugial regions and/or during the early stages of postglacial expansion is the most plausible explanation for the broadly similar distribution patterns of the shared, frequent chloroplast haplotypes in the two species. The fourth frequent, widespread haplotype was absent from S. latifolia and almost entirely restricted to Nordic S. dioica. It is most likely that this haplotype spread into the Nordic countries from a central or northern European source or from a refugial area in Russia. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161 , 153–170.     

Searching for the glacial refugia of Erebia euryale (Lepidoptera,Nymphalidae) – insights from mtDNA‐ and nDNA‐based phylogeography in the Western Carpathians

The refugial history and postglacial re‐colonization routes of Western Carpathian insects are insufficiently understood. Therefore, we investigated the spatio‐genetic structure (phylogeography) of Western Carpathian populations of Erebia euryale (Esper, 1805) (Lepidoptera, Nymphalidae) and inferred their colonization routes over the postglacial period. Our results provide new insights into the phylogeography and origin of Erebia euryale in the rarely studied region of the Western Carpathian Mountains. Their phylogeography, including glacial refugia and Pleistocene expansion routes, was reconstructed based on two mitochondrial (COI and CR) and three nuclear markers (CAD, MDH and IDH). Statistical parsimony networks showed the following geographic coherences: (1) populations from Romania and the Bukovské Mountains (Kremenec) grouped together; (2) a ?ergov group containing populations only from the ?ergov Mountains; (3) a Volovské Mountains group with populations from Koj?ovská ho?a and Slovak Paradise grouped together, most likely due to the lack of geographic isolation between the areas; (4) haplotypes characterized from the Volovské Mountains populations were widespread. Comparisons of Western Carpathian E. euryale COI‐haplotypes with haplotypes from the Southern Carpathians and Balkans suggest that the refugial areas were located in south‐eastern Europe in the Balkan region and Southern Carpathians. We also hypothesize possible central European contact zones in Slovakia for E. euryale in the Western Carpathians. Our results indicate that the Western Carpathians could have served as one of the contact zones between Eastern and Western populations, and additionally as an extra refugium in the southern part of the Volovské Mountains for populations also occurring in Czech mountain regions.     

A complex scenario of glacial survival in Mediterranean and continental refugia of a temperate continental vole species (Microtus arvalis) in Europe

The role of glacial refugia in shaping contemporary species distribution is a long-standing question in phylogeography and evolutionary ecology. Recent studies are questioning previous paradigms on glacial refugia and postglacial recolonization pathways in Europe, and more flexible phylogeographic scenarios have been proposed. We used the widespread common vole Microtus arvalis as a model to investigate the origin, locations of glacial refugia, and dispersal pathways, in the group of “Continental” species in Europe. We used a Bayesian spatiotemporal diffusion analysis (relaxed random walk model) of cytochrome b sequences across the species range, including newly collected individuals from 10 Iberian localities and published sequences from 68 localities across 22 European countries. Our data suggest that the species originated in Central Europe, and we revealed the location of multiple refugia (in both southern peninsulas and continental regions) for this continental model species. Our results confirm the monophyly of Iberian voles and the pre-LGM divergence between Iberian and European voles. We found evidence of restricted postglacial dispersal from refugia in Mediterranean peninsulas. We inferred a complex evolutionary and demographic history of M. arvalis in Europe over the last 50,000 years that does not adequately fit previous glacial refugial scenarios. The phylogeography of M. arvalis provides a paradigm of ice-age survival of a temperate continental species in western and eastern Mediterranean peninsulas (sources of endemism) and multiple continental regions (sources of postglacial spread). Our findings also provide support for a major role of large European river systems in shaping geographic boundaries of M. arvalis in Europe.     

Mitochondrial DNA variation in Pleistocene and modern Atlantic salmon from the Iberian glacial refugium

Current understanding of the postglacial colonization of Nearctic and Palearctic species relies heavily on inferences drawn from the phylogeographic analysis of contemporary generic variants. Modern postglacial populations are supposed to be representative of their Pleistocene ancestors, and their current distribution is assumed to reflect the different colonization success and dispersal patterns of refugial lineages. Yet, testing of phylogeographic models against ancestral genomes from glacial refugia has rarely been possible. Here we compare ND1 mitochondrial DNA variation in late Pleistocene (16,000-40,000 years before present), historical and contemporary Atlantic salmon (Salmo salar) populations from northern Spain and other regions of western Europe. Our study demonstrates the presence of Atlantic salmon in the Iberian glacial refugium during the last 40,000 years and points to the Iberian Peninsula as the likely source of the most common haplotype within the Atlantic lineage in Europe. However, our findings also suggest that there may have been significant changes in the genetic structure of the Iberian refugial stock since the last ice age, and question whether modern populations in refugial areas are representative of ice age populations. A common haplotype that persisted in the Iberian Peninsula during the Pleistocene last glacial maximum is now extremely rare or absent from European rivers, highlighting the need for caution when making phylogeographic inferences about the origin and distribution of modern genetic types.