New Insight into the Colonization Processes of Common Voles: Inferences from Molecular and Fossil Evidence

Elucidating the colonization processes associated with Quaternary climatic cycles is important in order to understand the distribution of biodiversity and the evolutionary potential of temperate plant and animal species. In Europe, general evolutionary scenarios have been defined from genetic evidence. Recently, these scenarios have been challenged with genetic as well as fossil data. The origins of the modern distributions of most temperate plant and animal species could predate the Last Glacial Maximum. The glacial survival of such populations may have occurred in either southern (Mediterranean regions) and/or northern (Carpathians) refugia. Here, a phylogeographic analysis of a widespread European small mammal (Microtus arvalis) is conducted with a multidisciplinary approach. Genetic, fossil and ecological traits are used to assess the evolutionary history of this vole. Regardless of whether the European distribution of the five previously identified evolutionary lineages is corroborated, this combined analysis brings to light several colonization processes of M. arvalis. The species' dispersal was relatively gradual with glacial survival in small favourable habitats in Western Europe (from Germany to Spain) while in the rest of Europe, because of periglacial conditions, dispersal was less regular with bottleneck events followed by postglacial expansions. Our study demonstrates that the evolutionary history of European temperate small mammals is indeed much more complex than previously suggested. Species can experience heterogeneous evolutionary histories over their geographic range. Multidisciplinary approaches should therefore be preferentially chosen in prospective studies, the better to understand the impact of climatic change on past and present biodiversity

Rodents and palaeogenetics: new perspectives.

10 pagesRodents are the most diversified mammalian order (484 extant genera including 2277 species), and they have a worldwide distribution. Palaeontological, morphological and molecular data have greatly helped to resolve their systematics and evolutionary history. However, some discrepancies remain between palaeontologists and molecular biologists. New techniques in molecular biology, and especially in palaeogenetics, allow us to have direct access to the hereditary material of extinct organisms, and they can compensate for some morphological limits. Unfortunately, few studies are dealing with rodent palaeogenetics, despite the amount of museum and fossil material available. Here, we review the major research activities in rodent palaeogenetics (phylogeny, genetic diversity, migration), and we present the promising research perspectives in this field (phylochronology, palaeoparasitology)

Developmental mechanisms in the evolution of phenotypic traits in rodent teeth.

32 pagesInternational audienc

Rongeurs et paléogénétique : nouvelles perspectives

Parmi les Mammifères, l’ordre des Rongeurs est de loin le mieux représenté (484 genres, comprenant 2277 espèces) à travers le monde. L’histoire évolutive et la systématique de ce groupe ont largement été étudiées par le biais de données paléontologiques, morphologiques et moléculaires. Cependant, il persiste certains points de désaccord entre paléontologistes et biologistes moléculaires. L’avancée des techniques de biologie moléculaire, et particulièrement en paléogénétique, permet désormais d’accéder au patrimoine génétique d’organismes disparus depuis plusieurs milliers d’années, mais aussi de pallier certaines limites de la morphologie. Malheureusement, peu de travaux se rapportant aux rongeurs intègrent des données paléogénétiques, malgré l’importante quantité de fossiles et de matériel conservés dans les musées. Nous présentons ici une synthèse des travaux effectués en paléogénétique (phylogénie, diversité génétique, migration) depuis l’origine de la discipline, ainsi que les champs disciplinaires prometteurs dans ce domaine (phylochronologie, paléoparasitologie).Rodents are the most diversified mammalian order (484 extant genera including 2277 species), and they have a worldwide distribution. Palaeontological, morphological and molecular data have greatly helped to resolve their systematics and evolutionary history. However, some discrepancies remain between palaeontologists and molecular biologists. New techniques in molecular biology, and especially in palaeogenetics, allow us to have direct access to the hereditary material of extinct organisms, and they can compensate for some morphological limits. Unfortunately, few studies are dealing with rodent palaeogenetics, despite the amount of museum and fossil material available. Here, we review the major research activities in rodent palaeogenetics (phylogeny, genetic diversity, migration), and we present the promising research perspectives in this field (phylochronology, palaeoparasitology).</p

Why all vole molars (Arvicolinae, Rodentia) are informative to be considered as proxy for Quaternary paleoenvironmental reconstructions.

13 pagesInternational audienceRodents are considered as a good model and as a good proxy to characterise Quaternary environments. Molars and incisors are the best-preserved remains and are found in abundance in the fossil record. Since several decades, the lower molars are mostly used for specific determinations. Instead of using qualitative and descriptive characters, morphometric methods provide now a general quantitative description of shape. Applying these new morphometric methods (outline analysis), we demonstrate that lower as well as upper molars are useful and efficient for palaeontological analyses within voles (Arvicolinae). Herein it is made evident that except the first lower molars, the use of all the other molars allows the improvement of specific determinations. It provides a better representation of abundance and diversity of the fossil record and thus involves more accurate paleoenvironmental reconstructions

Morphological modularity and assessment of developmental processes within the vole dental row (Microtus arvalis, Arvicolinae, Rodentia).

10 pagesInternational audienceKnowledge of mammalian tooth formation is increasing, through numerous genetic and developmental studies. The prevalence of teeth in fossil remains has led to an intensive description of evolutionary patterns within and among lineages based on tooth morphology. The extent to which developmental processes have influenced tooth morphologies and therefore the role of these processes in these evolutionary patterns are nonetheless challenging. Recent methodological advances have been proposed allowing the inference of developmental processes from adult morphologies and the characterization of the degree of developmental integration/modularity of morphological traits by studying the patterns of variation within and among individuals. This study focuses on the geometric shape of the lower molars of the vole species Microtus arvalis. Our results suggest (i) quasi-independence of each molar at the developmental level (developmental modules), even slightly stronger for the third molar supporting some genetic and developmental hypotheses and (ii) more pervasive integration processes among molars at the morphological level

Mitochondrial DNA Gene Diversity and Morphological Variability of the Common Vole (Microtus arvalis) in France

International audienc

Mitochondrial DNA Gene Diversity and Morphological Variability of the Common Vole (Microtus arvalis) in France

International audienc

Reappraisal of ‘chronospecies' and the use of Arvicola (Rodentia, Mammalia) for biochronology.

13 pagesInternational audienceThe water vole, genus Arvicola, is characterised by a broad geographic distribution throughout Europe and is widespread during the late Middle and Upper Pleistocene. This genus is used as a major biostratigraphic tool within the Quaternary. Specific determinations using the Schmelzband-Differenzierung-Quotient or SDQ have identified many chronospecies within the fossil species Arvicola cantiana (Hinton, 1910). As SDQ calculation remains limited, this study reappraises the Arvicola genus in terms of morphodiversity and morphospace using outline analysis which takes into account the tooth as a whole. Outline analysis suggests that one single species of Arvicola, A. cantiana, was present during the Pleistocene. This species shows great variability with no trends or patterns in morphospace. Thus, these results call into question the reliability of SDQ for specific determinations and throw doubt on the biochronological framework based on Arvicola