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Neogene orogenesis and climatic cycles strongly influenced inter- and intraspecific differentiation and variability of taxa. In this study, we focused on the southern margin of the western Palaearctic, known to be a geographically complex region. We performed mitochondrial DNA analyses of Buthus scorpions from the Moroccan Atlas Mountains, from the Hoggar Mountains in Algeria and from Tunisia, Iberia and Israel. Molecular species delimitation suggests the existence of ≥ 24 molecular operational taxonomic units. The data confirm complex differentiation patterns across the Atlas Mountains of Morocco, but structures in Iberia, Algeria and Tunisia have considerably lower complexity. This identifies the Atlas Mountain region as the most important differentiation centre of Buthus scorpions. Samples from the Hoggar Mountains (southern Algeria) cluster with those from the southernmost parts of Morocco in the middle and upper parts of the Draa Valley. This reinforces a recent connection of these regions. Samples from Israel are genetically similar to individuals from eastern Algeria and Tunisia. This suggests a widespread group across major parts of North Africa. Divergence time estimates indicate that differentiation in the genus began during the late Miocene, a period characterized by strong tectonic activities in this region. Further differentiation could be linked to subsequent climatic changes that have occurred since the end of the Miocene, with an increasing aridification of the Moroccan area. This also produced many microrefugia in the mountains of the area during the Pleistocene climatic fluctuations.

Drivers of evolution are often related to geographical isolation and/or diverging environmental conditions. Spatial variation in neutral genetic markers mostly reflects past geographical isolation, i.e. long-lasting allopatry, whereas morphology is often driven by local environmental conditions, resulting in more rapid evolution. In Europe, most thermophilic species persisted during the past glacial periods in geographically disjunct refugia, representing long-lasting isolates, frequently with diverging environmental conditions. This situation has driven the evolution of intraspecific signatures in species. Here, we analysed wing shape and wing pigmentation of the chalk-hill blue butterfly, Polyommatus coridon, across its entire distribution range restricted to the western Palaearctic. In addition, we compiled abiotic environmental parameters for each sampling site. Wing colour patterns differentiated a western and an eastern lineage. These lineages might represent two main Pleistocene refugia and differentiation centres, one located on the Italian Peninsula and the other in the Balkan region. The two lineages showed evidence of hybridization across Central Europe, from the Alps and across Germany. The intraspecific differentiation was strongest in the width of the brown band on the outer margin of the wings. The morphological structures obtained are in line with genetic signatures found in previous studies, but the latter are more fine-grained. Current environmental conditions, such as mean temperatures, were only marginally correlated with colour patterns. Our study underlines that Pleistocene range shifts, often resulting in allopatric isolation, shape intraspecific phenotypic structures within species; that pigmentation responds in a more sensitive manner to spatial disjunction than wing shape; and that morphometric and genetic structures in P. coridon provide concordant patterns and thus support identical biogeographical conclusions.

Many sedentary species with specific habitat demands occur in isolated populations and thus show strong intraspecific genetic differentiation, shaped either by geographical isolation or by local ecological adaptation to specific environmental conditions. The water-lily leaf beetle Galerucella nymphaeae has two ecotypes: one only found feeding as a specialist on just a few host plant species of the family Polygonaceae, and the other on various representatives of the family Nymphaeaceae as a generalist. To test whether the differentiation in ecotypes is also reflected in the population genetic structure, we combined amplified fragment length polymorhism data (> 500 polymorphic fragments; four sampling sites, 27–31 individuals each) with ex-situ feeding experiments (ten individuals from each site). We found that both ecotypes are genetically well differentiated. Furthermore, the genetic divergence between the two studied generalist Nymphaeaceae ecotype populations was also high. In contrast, the two specialist Polygonaceae ecotype populations clustered closely together (thus not depending on geographical isolation), indicating an ecology-driven genetic structuring. Our ex-situ reciprocal feeding experiment revealed that only individuals of the Polygonaceae ecotype are strictly dependent on their host plant family: individuals from populations feeding Polygonaceae are less likely to feed on species from the family Nymphaeaceae than the reverse. Our data show that host preference may drive genetic differentiation even more strongly than simple geographical distance.

Population genetic research has transformed from the study of genetic structures into a much wider and highly multidisciplinary research field. In this contribution, we outline the limitations of classic population genetic data and highlight the potential of combining molecular data with additional environmental, ecological and biological data sets in multidisciplinary approaches. The combination of data sets from various fields allows a more comprehensive understanding of extrinsic and intrinsic evolutionary processes affecting populations such as the distinction between genetic drift and natural selection. The integration of population size estimates and demographic dynamics as well as individual behaviour (embracing aspects like dispersal behaviour) allows for testing of adaptations to local environments and understanding time-lags frequently observed in molecular data. Modelling approaches are integrated at increasing rates into population genetic research to identify potential barriers and corridors. In our review, we therefore highlight multiple synergistic effects when combining population genetic data with morphological, ecological, behavioural data and modelling. We outline strengths and limitations and indicate future possibilities and challenges. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115, 1–12.

Habitat size, quality and isolation determine the genetic structure and diversity of populations and may influence their evolutionary potential and vulnerability to stochastic events. Small and isolated populations are subject to strong genetic drift and can lose much of their genetic diversity due to stochastic fixation and loss of alleles. The mountain white-eye Zosterops poliogaster, a cloud forest bird species, is exclusively found in the high mountains of East Africa. We analysed 13 polymorphic microsatellites for 213 individuals of this species that were sampled at different points in time in three mountain massifs differing in habitat size, isolation and habitat degradation. We analysed the genetic differentiation among mountain populations and estimated the effective population sizes. Our results indicate three mountain-specific genetic clusters. Time cohorts did not show genetic divergences, suggesting that populations are large enough to prevent strong drift effects. Effective population sizes were higher in larger and geographically interconnected habitat patches. Our findings underline the relevance of ecological barriers even for mobile species and show the importance of investigating different estimators of population size, including both approaches based on single and multiple time-points of sampling, for the inference of the demographic status of a population. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114, 828–836.

Quaternary climatic oscillations caused severe range expansions and retractions of European biota. During the cold phases, most species shifted to lower latitudes and altitudes, and expanded their distribution range northwards and to higher elevations during the warmer interglacial phases. These range shifts produced contrasting distribution dynamics, forming geographically restricted distribution patterns but also panmictic distributions, strongly dependent on the ecologic demands of the species. The two closely related butterfly species Erebia ottomana Herrich-Schaffer, 1847 and Erebia cassioides (Reiner & Hohenwarth, 1792) show subalpine and alpine distribution settings, respectively. Erebia ottomana is found up to the treeline (1400–2400 m a.s.l.), whereas E. cassioides reaches much higher elevations (from about 1800 m a.s.l. in the Retezat Mountains, in Romania, to 2800 m a.s.l.). Thus, both species cover diverging climatic niches, and thus might also have been distributed differently during the cold glacial stages. Individuals of these two species were sampled over the mountain areas of the Balkan Peninsula and genetically analysed using allozyme electrophoresis. Additionally, we performed species distribution models (SDMs) to simulate the distribution patterns of both species in the past (i.e. during the Last Glacial Maximum and the Atlanticum). Our genetic data show contrasting structures, with comparatively low genetic differentiation but high genetic diversity found in E. ottomana, and with stronger genetic differentiation and a lower level of genetic diversity, including many endemic alleles, occurring restricted to single mountain massifs in E. cassioides. The SDMs support a downhill shift during glacial periods, especially for E. ottomana, with possible interconnection among mountain regions. We conclude that during the cold glacial phases, both species are assumed to shift downhill, but persisted at different elevations, with E. ottomana reaching the foothills and spreading over major parts of the Balkan Peninsula. In contrast, E. cassioides (the truly alpine species) survived in the foothills, but did not reach and spread over lowland areas. This more widespread distribution at the Balkan Peninsula of E. ottomana compared with E. cassioides is strongly supported by our distribution models. As a consequence, long-term geographic restriction to distinct mountain massifs in E. cassioides versus panmixia in E. ottomana produced two contrasting evolutionary scenarios. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112, 569–583.

Glacial and interglacial cycles of the Pleistocene have led to severe range fluctuations of many species. These range shifts of the past often are reflected by extant genetic signatures. Retractions of distribution areas often have fostered splits into several small and isolated retreats as remnants of the formerly interconnected range. These processes often go in line with losses of intraspecific diversity. By contrast, large and interconnected distribution ranges mostly sustain high levels of genetic variability. The genetic impact of both scenarios strongly depends on the temporal scale. In the present study, we tested the genetic effects of an assumed long-lasting widespread distribution during glacial periods and more short-term population retractions to mountain archipelagos during warm stages. We analyzed polymorphic allozymes for individuals of the Eastern Large Heath butterfly, Coenonympha rhodopensis, including major parts of its distribution, such as central Italy and the Balkan Peninsula. Our data show extraordinarily high genetic diversity. The only remarkable genetic split is detectable between the central Apennines (Italy) and the Balkan mountain systems. The populations sampled over seven Balkan mountain systems (Jakupica, Shar Planina, Ossogovo, Pirin, Rila, Rhodopes, and Stara Planina) show low genetic differentiation. This low genetic differentiation and high genetic diversity diverges from the genetic structures frequently found in species with disjunct distributions. We therefore hypothesize that the obtained molecular structure is the product of down-slope shift during the last cold stage and subsequent expansion over the lowlands of the Balkan Peninsula. The current mountain restriction most probably occurred with the beginning of the postglacial warming, which is too short a time span to be of evolutionary relevance. Therefore, the recent high genetic diversities and low differentiation may still reflect long-lasting glacial panmixia but not (yet) the recent disjunction. The strong genetic differentiation between the Balkans and Italian Apennines must result from an earlier dispersal process, most probably from the Balkans to Italy. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110;, 281–290.

Tinamous have male-only parental care. For their mating system, simultaneous polygyny and sequential polyandry is proposed as an optimal model and is confirmed in all species according to the existing literature, except in the Ornate Tinamou. For the Ornate Tinamou a monogamous mating system is reported. However, this knowledge is based only on few direct observations in the field. Social monogamy in association with promiscuity would probably expose males to cuckoldry and, at the same time, constrain additional mating opportunities for them. To understand the evolutionary context for monogamy in the Ornate Tinamou, the present study aimed to determine whether this species is genetically monogamous or not and whether males are subjected to cuckoldry. We used polymorphic microsatellite markers to perform a sib-ship and paternity analysis based on samples from eggs and feathers of incubating males from four clutches. Promiscuity was found in all nests and the observed rate of cuckoldry ranged from 0% to 33.3%. These results rebut the consideration of monogamy for the Ornate Tinamou. Thus, the optimal model with polygynous males and polyandrous females prevails as an evolutionary stable strategy among tinamous, even in different social mating systems and despite high levels of cuckoldry.

When low dispersal ability of an organism meets geographical barriers, the evolution of inter- and intraspecific differentiation is often facilitated. In the Atlas massif of North Africa, the genus Buthus splits into several species and diverges into numerous genetic lineages, often following the orographic structures of mountain systems. Such high mountain ranges often act as barriers for species with reduced mobility even on small spatial scales. To study the effect of orographic structures on organisms with low dispersal ability, we collected 61 individuals of the scorpion species Buthus elmoutaouakili at 18 locations around the southwestern foothills of the High Atlas and Antiatlas and in the Sousse valley (western Morocco). We analyzed intraspecific differentiation patterns within this geographically restricted area of about 100 × 50 km using 452 bp of the cytochrome oxidase I mitochondrial gene. We detected 5 distinct genetic lineages. In a second analysis, we added 61 previously published sequences from Buthus species from Europe and North Africa. Using a molecular clock approach, we detected old splits (4-5 Ma) separating the samples from 1) the western High Atlas and north of these mountains, 2) the Sousse valley and adjoining mountain areas, and 3) the southwestern Antiatlas. Further differentiation happened in the first 2 geographical groups about 3 Ma. Thus, the divergence time estimates based on a Bayesian approach support the onset of differentiation into these main clades along the Pliocene (5-2.3 Ma) when climatic oscillations started and a constant global cooling preceded the glacial-interglacial cycles of the Pleistocene. Further genetic splits into parapatric groups are detectable for the Sousse valley main group in the early Pleistocene. The climatic oscillations of the Pliocene and early Pleistocene might have caused repeated range shifts, expansions, and retractions leading to repeated vicariance, hereby producing the hierarchical structure of genetic differentiation in B. elmoutaouakili. A taxonomic revision, including morphological and molecular data, is needed to assess the status of each of these Buthus scorpion lineages.

Cold-adapted species are thought to have had their largest distribution ranges in central Europe during the glacial periods. Postglacial warming caused severe range shifts of such taxa into higher latitudes and altitudes. We selected the boreomontane butterfly Lycaena helle (Denis & Schiffermuller, 1775) as an example to demonstrate the genetic effects of range changes, and to document the recent status of highly fragmented remnant populations. We analysed five polymorphic microsatellite loci in 1059 individuals sampled at 50 different localities scattered over the European distribution area of the species. Genetic differentiation was strong among the mountain ranges of western Europe, but we did not detect similarly distinct genetic groups following a geographical pattern in the more eastern areas. The Fennoscandian populations form a separate genetic group, and provide evidence for a colonization from southern Finland via northern Scandinavia to south-central Sweden. Species distribution modelling suggests a large extension of the spatial distribution during the last glacial maximum, but highlights strong retractions to a few mountain areas under current conditions. These findings, combined with our genetic data, suggest a more or less continuous distribution of L. helle throughout central Europe at the end of the last ice age. As a consequence of postglacial warming, the species retreated northwards to Fennoscandia and escaped increasing temperatures through altitudinal shifts. Therefore, the species is today restricted to population remnants located at the mountain tops of western Europe, genetically isolated from each other, and evolved into genetically unique entities. Rising temperatures and advancing habitat destruction threaten this wealth of biodiversity. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 155-168. ADDITIONAL KEYWORDS: climate change - fragmentation - Lepidoptera - microsatellites - mountains - postglacial relict - range shift - species distribution modelling.

The sea acts as an effective dispersal barrier for most terrestrial animal species. Narrow sea straits, therefore, often represent areas where species are able to disperse from one land mass to another. In the Mediterranean Sea, the narrowest connecting points between North Africa and Europe are the Strait of Gibraltar and the Strait of Sicily. In the past, climatic oscillations caused changing sea levels and thus influenced the permeability of these sea straits. We analysed the genetic structure of four butterfly species that all occur on both sides of the Strait of Sicily. In all four species, we observed a lack of genetic differentiation between the populations of North Africa and those of Italy. Species distribution models support the strong cohesiveness in that they show a largely continuous glacial distribution over Italy and North Africa. The data obtained reveal that there was a large exchange of individuals between Italy and the eastern Maghreb during the last ice age. This might not only be the case for the species under investigation in the present study, but also might represent a more general pattern for mobile thermophilic western Palearctic species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 818–830.

The glacial–interglacial cycles have caused severe range modifications of species' distributions. In Europe, thermophilic species had to retreat into geographically distinct southern refugia during glaciations. This process produced strong genetic imprints, which are still detectable by the present pattern of genetic differentiation and the distribution of regional diversity. To reveal the biogeographical imprints in the western Mediterranean, we analysed 26 populations of the butterfly Maniola jurtina spread over large areas of its European and North African distribution range. The samples were analysed using allozyme electrophoresis. We detected three genetic groups, divided into Western Europe, Central/Eastern Europe, and Italy with the Maghreb. The North African samples randomly cluster within the Italian samples. Even the population sampled in Morocco is genetically closely related to these samples and not to the geographically neighbouring Iberian ones. Parameters of genetic diversity showed similar values over the whole study area. The observed genetic pattern reflects possible glacial refugia in Europe located in the Iberian Peninsula and the Balkans. For North Africa and Italy, our data reveal a colonization of Africa originating from Italy.