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Thermo-hydroregulation strategies involve concurrent changes in functional traits related to energy, water balance and thermoregulation and play a key role in determining life-history traits and population demography of terrestrial ectotherms. Local thermal and hydric conditions should be important drivers of the geographical variation of thermo-hydroregulation strategies, but we lack studies that examine these changes across climatic gradients in different habitat types. Here, we investigated intraspecific variation of morphology and thermo-hydroregulation traits in the widespread European common lizard (Zootoca vivipara louislantzi) across a multidimensional environmental gradient involving independent variation in air temperature and rainfall and differences in habitat features (access to free-standing water and forest cover). We sampled adult males for morphology, resting metabolic rate, total and cutaneous evaporative water loss and thermal preferences in 15 populations from the rear to the leading edge of the distribution across an elevational gradient ranging from sea level to 1750 m. Besides a decrease in adult body size with increasing environmental temperatures, we found little effect of thermal conditions on thermo-hydroregulation strategies. In particular, relict lowland populations from the warm rear edge showed no specific ecophysiological adaptations. Instead, body mass, body condition and resting metabolic rate were positively associated with a rainfall gradient, while forest cover and water access in the habitat throughout the season also influenced cutaneous evaporative water loss. Our study emphasizes the importance of rainfall and habitat features rather than thermal conditions for geographical variation in lizard morphology and physiology.

We examined the contact zone of two parapatric species of grass snake (Natrix astreptophora and Natrix helvetica) in southern France. To this end, we used comprehensive sampling, analysed mtDNA sequences and microsatellite loci, and built Species Distribution Models for current and past climatic conditions. The contact zone had established by the mid-Holocene during range expansions from glacial refuges in the Iberian Peninsula (N. astreptophora) and southern or western France (N. helvetica). The contact zone represents a narrow bimodal hybrid zone, with steep genetic transition from one taxon to the other and rare hybridization, supporting species status for N. astreptophora and N. helvetica. Our results suggest that the steepness of the clines is a more robust tool for species delimitation than cline width. In addition, we discovered in western France, beyond the hybrid zone, a remote population of N. helvetica with genetic signatures of hybridization with N. astreptophora, most likely the result of human-mediated long-distance dispersal. For N. helvetica, we identified a southern and a northern population cluster, connected by broad-scale gene flow in a unimodal hybrid zone running across France. This pattern either reflects genetic divergence caused by allopatry in two microrefuges and subsequent secondary contact or introgression of foreign alleles into the southern cluster.

Dans de nombreuses disciplines scientifiques, des études expérimentales ou des suivis sur le terrain assurent la récolte de données. Celles-ci sont stockées sur des fichiers bruts avec un format intuitif, permettant une saisie facile par l’expérimentateur. Cependant, ce format brut est rarement directement compatible avec l’analyse des données récoltées et peut engendrer des analyses erronées ; il est nécessaire d’effectuer une mise en forme et un contrôle qualité des données. Face au nombre de jeux de données brutes croissants et toujours plus massifs, la discipline du numérique pour les sciences du vivant s’est développée. La programmation informatique représente une aide précieuse pour les modélisateurs puisqu’elle permet d’automatiser la mise en forme et le contrôle qualité qui nécessitent souvent un nettoyage des données. Dans cet article, nous présentons une collaboration entre informaticien et modélisateur dans le cadre du suivi de l’abondance d’espèces animales. Les données récoltées sur plusieurs feuilles d’un tableur sont regroupées sur une seule et leur qualité est vérifiée. Les diverses fonctionnalités du programme effectuant cette vérification ont été mises en place à l’aide de la méthode « agile », méthode de développement informatique constituée de sprints. Après la fourniture d’une version du programme, un nouveau sprint définit une nouvelle fonctionnalité à mettre en place par l’informaticien dans une nouvelle version du programme. La première version permet l’appropriation du jeu de données par l’informaticien grâce à la fonctionnalité de mise en forme. Une version plus avancée gère l’absence de données, puis d’autres contrôlent la qualité des données récoltées et rapportent le traitement des anomalies détectées – donnée absente ou erronée ou en dehors d’une plage spécifiée – dans un fichier texte. Ce programme informatique a été explicité afin qu’il puisse être ré-approprié et ré-utilisé. Sa version complète est déposée dans GitHub. Le lien est donné en conclusion.

International audience; Aim: Determining whether altitudinal shifts in species distributions leave molecular footprints on wild populations along their range margins from rear to leading edge. Location: South-west France. Methods: We compared the demographic and genetic variation in 42 wild populations of the Western oviparous subclade B2 of a cold adapted lizard (Zootoca vivipara louislantzi). These populations can be divided into four ecological units across altitudinal clines in South-west France (rear edge: 1300 m above sea level). Results: Within the rear edge were found the highest levels of inbreeding, genetic differentiation and evidence of interrupted gene flow compared to central or colonising areas. Within the leading edge, altitudinal range expansion occurred over the last centuries and populations showed relatively low genetic diversity. These demographic and genetic trends were better explained by inhospitable (warm and dry) climate conditions and forest cover. Main conclusions: This empirical evidence illustrates that molecular footprints of climate conditions and habitat quality on wild population trends can be perceived after recent events, which should be of particular importance to accurately understand and anticipate human-induced global change on wild species and ecosystems.

Because it is indicative of reproductive isolation, the amount of genetic introgression across secondary contact zones is increasingly considered in species delimitation. However, patterns of admixture at range margins can be skewed by the regional dynamics of hybrid zones. In this context, we posit an important role for phylogeographic history: hybrid zones located within glacial refugia (putatively formed during the Late-Pleistocene) should be better defined than those located in post-glacial or introduced ranges (putatively formed during the Holocene and the Anthropocene). We test this hypothesis in a speciation continuum of tree frogs from the Western Palearctic (Hyla), featuring ten identified contacts between species spanning Plio-Pleistocene to Miocene divergences. We review the rich phylogeographic literature of this group and examine the overlooked transition between H. arborea and H. molleri in Western France using a multilocus dataset. Our comparative analysis supports a trend that contacts zones resulting from post-glacial expansions and human translocations feature more extensive introgression than those established within refugial areas. Integrating the biogeographic history of incipient species, i.e. their age since first contact together with their genetic divergence, thus appears timely to draw sound evolutionary and taxonomic inferences from patterns of introgression across hybrid zones.

We characterize divergence times, intraspecific diversity and distributions for recently recognized lineages within the Hyla arborea species group, based on mitochondrial and nuclear sequences from 160 localities spanning its whole distribution. Lineages of H. arborea, H. orientalis, H. molleri have at least Pliocene age, supporting species level divergence. The genetically uniform Iberian H. molleri, although largely isolated by the Pyrenees, is parapatric to H. arborea, with evidence for successful hybridization in a small Aquitanian corridor (southwestern France), where the distribution also overlaps with H. meridionalis. The genetically uniform H. arborea, spread from Crete to Brittany, exhibits molecular signatures of a postglacial range expansion. It meets different mtDNA clades of H. orientalis in NE-Greece, along the Carpathians, and in Poland along the Vistula River (there including hybridization). The East-European H. orientalis is strongly structured genetically. Five geographic mitochondrial clades are recognized, with a molecular signature of postglacial range expansions for the clade that reached the most northern latitudes. Hybridization with H. savignyi is suggested in southwestern Turkey. Thus, cryptic diversity in these Pliocene Hyla lineages covers three extremes: a genetically poor, quasi-Iberian endemic (H. molleri), a more uniform species distributed from the Balkans to Western Europe (H. arborea), and a well-structured Asia Minor-Eastern European species (H. orientalis).

International audience; Despite early reports of its presence, no recent data exist on the distribution of the American bullfrog in Europe, the causes of introduction, or the trends of populations. We monitored the European situation at two spatial scales. In SW France, we performed call surveys over 2,500 wetlands. We found bullfrogs over about 2,000 km(2), apparently the European area in which the strongest expansion of bullfrogs is taking place. In addition, we used questionnaires to investigate the situation at the continental scale. At least 25 independent introductions occurred in Europe; eradication attempts were successful three times, and bullfrog populations are present in five countries. Education programs and monitoring are necessary to reduce the rate of introduction and to start management action as soon as possible.

International audience; The Ocellated Lizard, Timon lepidus (Daudin 1802) occupies the Mediterranean regions of southwestern Europe (Portugal, Spain, France, and the extreme northwest of Italy). Over the last decades, a marked decline in its population has been observed, particularly on the northern edge of its distribution. As a result, it is currently considered a threatened species, especially in France and Italy. In France, a national action plan for its conservation has been put in place. In this study, ecological niche modelling (ENM) was carried out over the entire area of France in order to evaluate the species' potential distribution, more accurately define its ecological niche, guide future surveys, and inform land use planning so this species can be better taken into consideration. The modelling used data representing 2,757 observation points spread over the known range of the species, and 34 ecogeographical variables (climate, topography, and vegetation cover) were evaluated. After removing correlated variables, models were fitted with several combinations of variables using eight species distribution model (SDM) algorithms, and then their performance was assessed using three model accuracy metrics. Iterative trials changing the input variables were used to obtain the best model. The optimized model included nine determining variables. The results indicate the presence of this species is linked primarily to three climate variables: precipitation in the driest month, precipitation seasonality, and mean temperature in the driest quarter. The model was checked by a sample dataset that was not used to fit the model, and this validation dataset represented 25% of the overall field observations. Of the known occurrence locations kept aside to check the results, 94% fell within the presence area predicted by the modelled map with a presence probability greater than 0.7, and 90% fell within the area with a presence probability ranging from 0.8 to 1, which represents a very high predictive value. These results indicate that the models closely matched the observed distribution, suggesting a low impact of either geographical factors (barriers to dispersal), historical factors (dispersal process), or ecological factors (e.g., competition, trophic resources). The overlap between the predicted distribution and protected areas for this species reveals that less than 1% of the potential distribution area is protected by strong regulatory measures (e.g., national parks and natural reserves). The knowledge obtained in this study allows us to recommend some guidelines that would favor the conservation of this species.; Résumé.-Le lézard ocellé, Timon lepidus (Daudin 1802), occupe les régions méditerranéennes du sud-ouest de l'Europe (Portugal, Espagne, France, et extrême nord-ouest de l'Italie). Au cours des dernières décennies, un fort déclin des populations a été observé, particulièrement aux marges nord de sa distribution. Il est donc considéré comme une espèce menacée, spécialement en France et en Italie. En France, il bénéficie d'un plan national d'actions en faveur de sa préservation. La modélisation de sa distribution a été conduite sur l'ensemble du territoire national en vue d'estimer sa distribution potentielle, préciser sa niche écologique, orienter les prospections futures et permettre une meilleure prise en compte de l'espèce dans l'aménagement du territoire. Le travail de modélisation repose sur 2757 points d'observation répartis sur l'ensemble de la distribution connue de l'espèce, confrontés à 34 variables climatiques, topographiques, et de couvert végétal. Après suppression des variables autocorrélées, plusieurs combinaisons de variables ont été testées, et leur performances évaluées à partir de huit algorithmes SDM. Le meilleur modèle retient neuf variables, déterminées par l'algorithme ayant la meilleure performance. Les modèles montrent que la présence de l'espèce est principalement déterminée par la sécheresse et la température estivale: précipitations au cours du mois lemois le plus sec, saisonnalité des précipitations et température moyenne des trois mois les plus chauds. Lavalidation du modèle sur la base d’un échantillon totalisant 25 % du total des observations, non inclus dans lemodèle, montre que 94 % des données de validation se placent dans l’aire potentielle au seuil de probabilité de0,7, et 90 % pour une probabilité comprise entre 0,8 et 1. Ceci donne une valeur prédictive très élevée au modèleretenu. On constate une étroite concordance entre la distribution potentielle et la distribution réalisée, ce quisuggère une faible influence des facteurs géographiques (obstacles à la dispersion), historiques (processusde dispersion) ou écologiques (compétition, ressources trophiques, etc.). Le croisement cartographique entrel’aire potentielle de l’espèce et les espaces protégés montre que moins de 1 % de l’aire potentielle est couvertepar des mesures réglementaires fortes (parcs nationaux et réserves naturelles). En conclusion, le travail donnedes orientations pour améliorer la connaissance de la distribution de l’espèce et des pistes de réflexion enfaveur de sa conservation.