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.     

Resilient forest faunal communities in South Africa: a legacy of palaeoclimatic change and extinction filtering?

Aim To examine the influence of climatic extinction filtering during the last glacial maximum (LGM; c. 18,000 yr bp ) and of the subsequent recolonization of forest faunas on contemporary assemblage composition in southern African forests. Location South Africa, Mozambique, Swaziland, Zimbabwe. Methods Data comprised presence/absence by quarter‐degree grid cell for forest‐dependent and forest‐associated birds, non‐volant mammals and frogs. Twenty‐one forest subregions were assigned to one of three previously identified forest types: Afrotemperate, scarp, and Indian Ocean coastal belt. Differences among forest types were examined through patterns and gradients of species richness and endemism, assemblage similarity, species turnover, and coefficients of species dispersal direction. The influence of contemporary environment on assemblage composition was investigated using partial canonical correspondence analysis. Several alternative biogeographical hypotheses for the recolonization of forest faunas were tested. Results Afrotemperate faunas are relatively species‐poor, have low species turnover, and are unsaturated and infiltrated by generalist species. In northern and central regions, communities are supplemented by recolonization from scarp forest refugia, and among frogs by autochthanous speciation in localized refugia. Scarp faunas are relatively species‐rich, contain many forest‐dependent species, have high species turnover, and overlap with coastal and Afrotemperate faunas. Coastal forests are relatively species‐rich with high species turnover. Main conclusions Afrotemperate communities were affected most by climatic extinction filtering events. Scarp forests were Afrotemperate refugia during the LGM and are a contemporary overlap zone between Afrotemperate and coastal forest. Coastal faunas derive from post‐LGM colonization along the eastern seaboard from tropical East African refugia. The greatest diversity is achieved in scarp and coastal forest faunas in northern KwaZulu–Natal province. This historical centre of diversity has influenced the faunal diversity of nearly all other forests in South Africa. The response of vertebrate taxa to large‐scale, historical processes is dependent on their relative mobility: forest birds best illustrate patterns resulting from post‐glacial faunal dispersal, while among mammals and frogs the legacy of climatic extinction filtering remains stronger.     

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.     

Late Pleistocene to Holocene distributional stasis in scorpions along the Baja California peninsula

The biota of the Baja California peninsula (BCP) assembled in response to a complex history of Neogene tectonics and Quaternary climates. We constructed species distribution models (SDMs) for 13 scorpion species from the BCP to compare current suitable habitat with that at the latest glacial maximum about 21 000 years ago. Using these SDMs, we modelled climatic suitability in relation to latitude along the BCP. Our SDMs suggested that most BCP scorpion distributions have remained remarkably conserved across the latest glacial to interglacial climatic transformation. Three areas of climatic suitability coincide remarkably well with genetic discontinuities in other co‐distributed taxa along the BCP, indicating that long‐term persistence of zones of abrupt climatic transition offer a viable alternative, or synergistic enhancement, to hypotheses of trans‐peninsular seaways as drivers of peninsular divergences. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 450–461.     

Tracking the ice: Subterranean harvestmen distribution matches ancient glacier margins

Biogeographic studies often underline the role of glacial dynamism during Pleistocene (1.806–0.011 Mya) in shaping the distribution of subterranean species. Accordingly, it is presumed that present‐day distribution of most specialized cold‐adapted (cryophilic) cave‐dwelling species should bear the signatures of past climatic events. To test this idea, we modelled the distribution of specialized cold‐adapted subterranean alpine harvestmen (Arachnida: Opiliones: Ischyropsalididae: Ischyropsalis). We found that the distance from the glacier margins during Last Glacial Maximum (LGM; about 22,000 years ago) was the most important predictor of their present‐day distribution. In particular, the peak in the probability of occurrence of alpine subterranean Ischyropsalis was found to be in close proximity to the LGM glacier, with a sharp drop at a distance of 30 km from the ice margin. In light of the role played by past climatic events in determining the species current range, we briefly discuss their biogeographic history and the role played by glacial refugia dynamics in determining the current distribution of these species. We argue that low dispersal harvestmen such as our model species can be used as biological indicators for tracking past glaciations and other similar biogeographic events.     

Multiple Glacial Refugia of the Low-Dispersal Ground Beetle Carabus irregularis: Molecular Data Support Predictions of Species Distribution Models

Classical glacial refugia such as the southern European peninsulas were important for species survival during glacial periods and acted as sources of post-glacial colonisation processes. Only recently, some studies have provided evidence for glacial refugia north of the southern European peninsulas. In the present study, we combined species distribution models (SDMs) with phylogeographic analyses (using mitochondrial DNA = mtDNA) to investigate if the cold-adapted, stenotopic and flightless ground beetle species, Carabus irregularis, survived the Last Glacial Maximum (LGM) in classical and/or other refugia. SDMs (for both a western European and for a Carpathian subgroup) were calculated with MAXENT on the basis of 645 species records to predict current and past distribution patterns. Two mtDNA loci (CO1 and ND5, concatenated sequence length: 1785 bp) were analyzed from 91 C. irregularis specimens to reconstruct the phylogeography of Central and eastern European populations and to estimate divergence times of the given lineages. Strong intra-specific genetic differentiation (inter-clade Φ_ST values ranged from 0.92 to 0.99) implied long-term isolation of major clades and subsclades. The high divergence between the nominate subspecies and the Carpathian subspecies C. i. montandoni points to two independent species rather than subspecies (K-2P distance 0.042 ± 0.004; supposed divergence of the maternal lineages dated back 1.6 to 2.5 million years BP) differing not only morphologically but also genetically and ecologically from each other. The SDMs also inferred classical as well as other refugia for C. irregularis, especially north of the Alps, in southeastern Europe and in the Carpathians. The coincidences between the results of both methods confirm the assumption of multiple glacial refugia for the studied species and the usefulness of combining methodological approaches for the understanding of the history of low-dispersal insect species.     

Historical stability of diversity patterns in African estrildid finches (Aves: Estrildidae)?

Studying shifts in species diversity through time and space is an essential component of many aspects of biogeography and ecology. In this study, we predict the potential distribution of 61 species of African estrildid finches in order to assess current and past diversity patterns. Models were projected onto two climatic scenarios (Community Climate System Model, CCSM, and Model for Interdisciplinary Research on Climate, MIROC) representing past climate conditions, as might be expected during the Last Glacial Maximum 21 000 years BP. Subsequent overlays of the resulting potential distributions were conducted under different dispersal assumptions and compared with expert maps. Our results suggest highly similar current distribution patterns obtained by both methods. Projections onto Pleistocene scenarios showed similar patterns, with only small differences under limited and unlimited dispersal assumptions. Looking separately at diversity patterns predicted for forest and savannah species, diversity hot spots of forest species under MIROC conditions were consistent with suggested forest refugia, but were inconsistent under CCSM conditions. According to our models, savannah species were more widely distributed during the cooler and drier conditions of the Pleistocene. By using ecological niche models we show that current diversity patterns of a whole species group may have changed only slightly since the Pleistocene, suggesting a pattern of general spatial stability. However, we emphasize the importance of using different climatic scenarios as well as including the supposed dispersal of organisms in the modelling, as these factors influence results on a broad scale. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 455–470.     

Mitochondrial DNA of pre‐last glacial maximum red deer from NW Spain suggests a more complex phylogeographical history for the species

The major climatic oscillations that characterized the Quaternary had a great influence on the evolution and distribution of several species. During cold periods, the distribution of temperate‐adapted species became fragmented with many surviving in southern refugia (Iberian, Italian, and Balkan Peninsulas). Red deer was one of the species that contracted its original range to southern refugia. Currently, two main lineages have been described for the species: western and eastern. We have analyzed fossils pre‐dating the last glacial maximum (LGM) from Liñares cave (NW Spain) that belongs to the peripheral range of the western clade, and fossils from the Danish Holocene belonging to the central part of the same clade. Phylogenetic analyses place our samples in the western clade. However, some specimens from Liñares represent an early split in the tree along with other pre‐LGM western samples from previous studies. Despite low bootstrap values in the Bayesian phylogenies, haplotype networks connect these foreign haplotypes to the eastern clade. We suggest a mixed phylogeographical model to explain this pattern with range expansions from the east during the expansion phase after the cold periods in marine isotope stage 3. We find slight isolation by distance in post‐LGM populations that could be a consequence of the recolonization from southern refugia after the LGM.     

Past and present potential distribution of the Iberian Abies species: a phytogeographic approach using fossil pollen data and species distribution models

Aim Quaternary palaeopalynological records collected throughout the Iberian Peninsula and species distribution models (SDMs) were integrated to gain a better understanding of the historical biogeography of the Iberian Abies species (i.e. Abies pinsapo and Abies alba). We hypothesize that SDMs and Abies palaeorecords are closely correlated, assuming a certain stasis in climatic and topographic ecological niche dimensions. In addition, the modelling results were used to assign the fossil records to A. alba or A. pinsapo, to identify environmental variables affecting their distribution, and to evaluate the ecological segregation between the two taxa. Location The Iberian Peninsula. Methods For the estimation of past Abies distributions, a hindcasting process was used. Abies pinsapo and A. alba were modelled individually, first calibrating the model for their current distributions in relation to the present climate, and then projecting it into the past—the last glacial maximum (LGM) and the Middle Holocene periods—in relation to palaeoclimate simulations. The resulting models were compared with Iberian‐wide fossil pollen records to detect areas of overlap. Results The overlap observed between past Abies refugia—inferred from fossil pollen records—and the SDMs helped to construct the Quaternary distribution of the Iberian Abies species. SDMs yielded two well‐differentiated potential distributions: A. pinsapo throughout the Baetic mountain Range and A. alba along the Pyrenees and Cantabrian Range. These results propose that the two taxa remained isolated throughout the Quaternary, indicating a significant geographical and ecological segregation. In addition, no significant differences were detected comparing the three projections (present‐day, Mid‐Holocene and LGM), suggesting a relative climate stasis in the refuge areas during the Quaternary. Main conclusions Our results confirm that SDM projections can provide a useful complement to palaeoecological studies, offering a less subjective and spatially explicit hypothesis concerning past geographic patterns of Iberian Abies species. The integration of ecological‐niche characteristics from known occurrences of Abies species in conjunction with palaeoecological studies could constitute a suitable tool to define appropriate areas in which to focus proactive conservation strategies.     

The not‐so‐Irish spurge: Euphorbia hyberna (Euphorbiaceae) and the Littletonian plant ‘steeplechase’

The disjunct distributions of the Lusitanian flora, which are found only in south‐west Ireland and northern Iberia, and are generally absent from intervening regions, have been of great interest to biogeographers. There has been much debate as to whether Irish populations represent relicts that survived the Last Glacial Maximum (LGM; approximately 21 kya), or whether they recolonized from southern refugia subsequent to the retreat of the ice and, if so, whether this occurred directly (i.e. the result of long distance dispersal) or successively (i.e. in the manner of a ‘steeplechase’, with the English Channel and Irish Sea representing successive ‘water‐jumps’ that have to be successfully crossed). In the present study, we used a combined palaeodistribution modelling and phylogeographical approach to determine the glacial history of the Irish spurge, Euphorbia hyberna, the sole member of the Lusitanian flora that is also considered to occur naturally in south‐western England. Our findings suggest that the species persisted through the LGM in several southern refugia, and that northern populations are the result of successive recolonization of Britain and Ireland during the postglacial Littletonian warm stage, akin to the ‘steeplechase’ hypothesis. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 249–259.     

Rethinking long‐term vegetation dynamics: multiple glacial refugia and local expansion of a species complex

Evidence is accumulating that some arcto‐boreal plant taxa persisted through the last glacial maximum (LGM) in Alaska and adjacent Canada. However, the spatial patterns of glacial persistence and associated postglacial colonization remain largely unknown. In this study, we investigated the LGM refugia of an alder (Alnus) species complex (n = 3 taxa) and assess the spatiotemporal dynamics of Alnus in this vast region. Specifically, we conducted high‐throughput DNA sequencing (ddRADseq) on Alnus foliar samples collected from a dense population network to investigate patterns of genetic structure and infer the presence of glacial lineages. Species distribution modeling (SDM) was used to investigate the probability and possible locations of glacial persistence. These analyses were integrated and then compared with fossil pollen data to identify the locations of refugial populations and spatial patterns of postglacial colonization. Our genetic analyses revealed two glacial lineages with separate geographic origins for each Alnus taxon, suggesting that the genus persisted in multiple LGM refugia. Non‐overlapping hindcast distributions based on SDMs further support the presence of multiple, spatially distinct refugia. These ddRADseq and SDM results, in conjunction with reassessment of fossil pollen records, suggest that Alnus expanded from several population nuclei that existed during the LGM and coalesced during the Holocene to form its present range. These results challenge the unidirectional model for postglacial vegetation expansion, implying that climate buffering associated with landscape heterogeneity and adaptation to millennial‐scale environmental variability played important roles in driving late‐Quaternary population dynamics.     

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.     

Spatial distributions of European Tenebrionidae point to multiple postglacial colonization trajectories

Many studies have found that species richness in the Western Palaearctic follows a latitudinal trend, yet the importance of geographical and ecological factors in shaping species ranges remains obscure. In this article, we present geographical patterns of darkling beetles (Tenebrionidae), a species‐rich group of arthropods. We relate the spatial distributions of species, instead of simply species richness, to spatial and climatic gradients, and test the effects of area (by species–area relationships), latitude (by various climatic gradients) and environmental diversity (by elevation) using simultaneous autoregressive models to identify major correlates of species richness. We then use nestedness and co‐occurrence analyses to identify glacial refugial centres and postglacial dispersal trajectories responsible for current species ranges. Our results indicate the presence of two refugial centres (in the Iberian and Balkan peninsulas) that appear to have been particularly important in shaping extant tenebrionid ranges. Northern countries were selectively colonized by more tolerant and, possibly, more mobile species, which survived in southern refugia during the Pleistocene glacial maxima, whereas the low dispersal capabilities of many species that evolved in these southern isolated areas prevented their spread northwards. High levels of endemism recorded in Spain and Sardinia suggest that the faunas of these regions originated during the Tertiary period and have remained substantially isolated. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 318–329.     

The Quaternary evolutionary history,potential distribution dynamics,and conservation implications for a Qinghai–Tibet Plateau endemic herbaceous perennial,Anisodus tanguticus (Solanaceae)

Various hypotheses have been proposed about the Quaternary evolutionary history of plant species on the Qinghai–Tibet Plateau (QTP), yet only a handful of studies have considered both population genetics and ecological niche context. In this study, we proposed and compared climate refugia hypotheses based on the phylogeographic pattern of Anisodus tanguticus (three plastid DNA fragments and nuclear internal transcribed spacer regions from 32 populations) and present and past species distribution models (SDMs). We detected six plastid haplotypes in two well‐differentiated lineages. Although all haplotypes could be found in its western (sampling) area, only haplotypes from one lineage occurred in its eastern area. Meanwhile, most genetic variations existed between populations (F_ST = 0.822). The SDMs during the last glacial maximum and last interglacial periods showed range fragmentation in the western area and significant range contraction in the eastern area, respectively, in comparison with current potential distribution. This species may have undergone intraspecific divergence during the early Quaternary, which may have been caused by survival in different refugia during the earliest known glacial in the QTP, rather than geological isolation due to orogenesis events. Subsequently, climate oscillations during the Quaternary resulted in a dynamic distribution range for this species as well as the distribution pattern of its plastid haplotypes and nuclear genotypes. The interglacial periods may have had a greater effect on A. tanguticus than the glacial periods. Most importantly, neither genetic data nor SDM alone can fully reveal the climate refugia history of this species. We also discuss the conservation implications for this important Tibetan folk medicine plant in light of these findings and SDMs under future climate models. Together, our results underline the necessity to combine phylogeographic and SDM approaches in future investigations of the Quaternary evolutionary history of species in topographically complex areas, such as the QTP.     

Palaeodistribution modelling does not support disjunct Pleistocene refugia in several Central American plant taxa

Aim We combine evidence from palaeoniche modelling studies of several tree species to estimate the extent of Central American forest during the Last Glacial Maximum (LGM). In particular, we ask whether the distributions of these species are likely to have changed since the LGM, and whether LGM distributions coincide with previously proposed Pleistocene refugia in this area. Location Central American wet and seasonally dry forests. Methods We developed ecological niche models using two simulations of Pleistocene climate and occurrence data for 15 Neotropical plant species. We focused on palaeodistribution models of three ‘focal’ tree species that occur in wet and seasonally dry Central American forests, where recent phylogeographic data suggest Pleistocene differentiation coincident with previously proposed refugia. We added predictions from six wet‐forest and six seasonally dry‐forest obligate plant species to gauge whether Pleistocene range shifts were specific to habitat type. Correlation analyses were performed between projected LGM and present distributions, LGM distributions and previously proposed refugia. We also asked whether modelled palaeodistributions were smaller than their current extents. Results According to our models, the ranges of the study species were not reduced during the LGM, and did not correlate with refugial models, regardless of habitat type. Relative range sizes between present and LGM distributions did not indicate significant range changes since the LGM. However, relative range sizes differed overall between the two palaeoclimate models. Main conclusions Many of the modelled palaeodistributions of study species were not restricted to refugia during the LGM, regardless of forest type. While constrained from higher elevations, most species found suitable habitat at coastal margins and on newly exposed land due to lowered sea levels during the LGM. These results offer no corroboration for Pleistocene climate change as a driver of genetic differentiation in the ‘focal’ species. We offer alternative explanations for genetic differentiation found in plant species in this area.     

Evolutionary history of the scorpionfly Dicerapanorpa magna (Mecoptera,Panorpidae)

Climate changes can have fundamental impacts on the distributional patterns of montane species, and range shifts frequently lead to allopatric divergence followed by the establishment of secondary contact zones. Many European and North American organisms have retreated to southern refugia during glacial periods and colonized northward during postglacial periods, but little is known about the evolutionary response of cold‐adapted insects to Pleistocene climate changes in eastern Asia. The scorpionfly Dicerapanorpa magna (Chou), with cold temperate habitat preference and weak dispersal ability, provides a good model system to explore how climate changes have influenced the distribution and divergence of cold‐adapted insects in eastern Asia. This study reconstructed the demographic dynamics and evolutionary history of D. magna with phylogeographic approaches, and predicted the species’ suitable areas under the Last Glacial Maximum (LGM) and current scenarios with the ecological niche modelling analysis. The mitochondrial cytochrome c oxidase subunit I resolved three phylogenetic lineages in D. magna dating back to Pleistocene, corresponding well with the geographically isolated Qinling, Bashan and Minshan Mountains. The ecological niche modelling recovered the suitable habitats for D. magna were the Qinling and Bashan Mountains under LGM and current conditions. The three lineages of D. magna might be in a process of incipient speciation, and likely derived their current distribution from separate glacial origins, followed by vicariance and divergence.     

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.     

Imprints of multiple glacial refugia in the Pyrenees revealed by phylogeography and palaeodistribution modelling of an endemic spider

Mediterranean mountain ranges harbour highly endemic biota in islandlike habitats. Their topographic diversity offered the opportunity for mountain species to persist in refugial areas during episodes of major climatic change. We investigate the role of Quaternary climatic oscillations in shaping the demographic history and distribution ranges in the spider Harpactocrates ravastellus, endemic to the Pyrenees. Gene trees and multispecies coalescent analyses on mitochondrial and nuclear DNA sequences unveiled two distinct lineages with a hybrid zone around the northwestern area of the Catalan Pyrenees. The lineages were further supported by morphological differences. Climatic niche‐based species distribution models (SDMs) identified two lowland refugia at the western and eastern extremes of the mountain range, which would suggest secondary contact following postglacial expansion of populations from both refugia. Neutrality test and approximate Bayesian computation (ABC) analyses indicated that several local populations underwent severe bottlenecks followed by population expansions, which in combination with the deep population differentiation provided evidence for population survival during glacial periods in microrefugia across the mountain range, in addition to the main Atlantic and Mediterranean (western and eastern) refugia. This study sheds light on the complexities of Quaternary climatic oscillations in building up genetic diversity and local endemicity in the southern Europe mountain ranges.     

Investigating past range dynamics for a weed of cultivation,Silene vulgaris

Since the last glacial maximum (LGM), many plant and animal taxa have expanded their ranges by migration from glacial refugia. Weeds of cultivation may have followed this trend or spread globally following the expansion of agriculture or ruderal habitats associated with human‐mediated disturbance. We tested whether the range expansion of the weed Silene vulgaris across Europe fit the classical model of postglacial expansion from southern refugia, or followed known routes of the expansion of human agricultural practices. We used species distribution modeling to predict spatial patterns of postglacial expansion and contrasted these with the patterns of human agricultural expansion. A population genetic analysis using microsatellite loci was then used to test which scenario was better supported by spatial patterns of genetic diversity and structure. Genetic diversity was highest in southern Europe and declined with increasing latitude. Locations of ancestral demes from genetic cluster analysis were consistent with areas of predicted refugia. Species distribution models showed the most suitable habitat in the LGM on the southern coasts of Europe. These results support the typical postglacial northward colonization from southern refugia while refuting the east‐to‐west agricultural spread as the main mode of expansion for S. vulgaris. We know that S. vulgaris has recently colonized many regions (including North America and other continents) through human‐mediated dispersal, but there is no evidence for a direct link between the Neolithic expansion of agriculture and current patterns of genetic diversity of S. vulgaris in Europe. Therefore, the history of range expansion of S. vulgaris likely began with postglacial expansion after the LGM, followed by more recent global dispersal by humans.