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International audience; Human-mediated species dispersal across the Mediterranean stretches back at least 10,000 years and has left an indelible stamp on present-day biodiversity. Believed to be a descendant of the Asiatic mouflon (Ovis gmelini gmelinii), the Corsican mouflon (O. g. musimon) was translocated during the Neolithic as ancestral livestock by humans migrating from the Fertile Crescent to the Western Mediterranean. Today, two geographically limited and disconnected populations can be found in Corsica. Whether they originated from distinct founders or one ancestral population that later split remains unknown, although such information is pivotal for the species' management on the island. We genotyped 109 and 176 individuals at the Cytochrome-b gene and 16 loci of the microsatellite DNA, respectively, to gain insights into the natural history of the Corsican mouflon. We found evidence confirming that the Asiatic was the ancestor of the Corsican mouflon, which should thus be unvaryingly referred to as O. g. musimon, i.e. as a subspecies of the Asiatic mouflon. Haplotype divergence dating and the investigation of genetic structure highlighted a strong and ancient genetic differentiation between the two Corsican populations. Approximate Bayesian Computation pointed to the introduction of a single group of founders as the most reliable scenario for the origin of the entire Corsican population. Later, this ancestral stock would have decreased in number, facing genetic bottlenecks and eventually resulting in two divergent demes. Splitting most likely occurred several hundred years ago. Their shared past notwithstanding, we discuss whether the two relic Corsican mouflon populations should be now considered as distinct management units.

Several individual, environmental and parasitic factors can influence the impacts of parasites on host's fitness and on host's ability to transmit these parasites to new hosts. Identifying these factors and the individuals who play a greater role in parasite transmission is of main concern for the development of parasite control strategies. In the present study, we aimed to describe the diversity of gastrointestinal parasites and to identify the individual factors influencing the faecal spreading of parasites in a free-ranging population of Mediterranean mouflon. From the analysis of 433 faecal samples, we found Eimeria spp. and gastrointestinal strongyles (GIS) were the most common parasites (>94%). The faecal oocyst counts of Eimeria spp. were the highest during the first years of life. It was 1.6 times higher in females than in males and 2.5 times higher in individuals in poor than in good body condition. Similarly, the faecal egg count of GIS was higher in females and decreased with age, but only in males. Finally, reproductive females had GIS faecal egg count values 2.6 times higher than non-reproductive females. Management strategies of parasites should thus primarily focus on reproductive females and young individuals in poor body condition as they represent the main contamination source of the environment.

Resilience capacities of hydrothermal vent species are largely dependent on their dispersal abilities. Characterizing gene flow and identifying biotic and/or abiotic factors impacting population exchanges are thus of prime importance. In this study we focused on Peltospira smaragdina, a gastropod species inhabiting hydrothermal vent chimneys along the Mid-Atlantic Ridge (MAR). We genotyped 237 individuals from 6 hydrothermal fields (23°N to 45°N) at 12 522 SNPs using a double-digest restriction-site associated DNA sequencing (ddRAD). Using population genetics clustering approaches, three genetic groups were detected. These groups corresponded to the Moytirra vent field, fields of the Azorean triple junction, and the deeper sites of TAG, Snake-Pit and Broken-Spur. Fst values were in accordance with such results. Half of the individuals of Rainbow were however more related to the third and most southern group. Ancestry coefficient confirmed local admixture between the Lucky-Strike and TAG/Snake-Pit/Broken-Spur genetic clusters at Rainbow. These results indicated that (1) gene flow is greatly impeded between Moytirra and the other fields sampled, (2) TAG, Snake-Pit and Broken-Spur may be panmictic, and (3) the Rainbow field may represent a putative ‘hybrid’ zone receiving migrants from TAG/Snake-Pit/Broken-Spur at a rather low rate. Several hypotheses might explain genetic breaks between vent fields, such as the presence of topographical barriers (fracture zones) or decreasing depth near to the Azorean Triple Junction. Genetic differences observed along the MAR between Peltospira smaragdina and other species highlighted the need of performing comparative studies on several species having contrasted life-history traits, as planned in the iAtlantic WP1.

Cryptic species diversity is known to be common in bats but remains challenging to study in these mammals, whose natural history traits render their sampling and monitoring challenging. For these animals, indirect genetic approaches provide a powerful tool to gain insight into the evolutionary history and ecology of cryptic bat species. The speciation history of the polyphyletic

Several individual, environmental and parasitic factors can influence the impacts of parasites on host's fitness and on host's ability to transmit these parasites to new hosts. Identifying these factors and the individuals who play a greater role in parasite transmission is of main concern for the development of parasite control strategies. In the present study, we aimed to describe the diversity of gastrointestinal parasites and to identify the individual factors influencing the faecal spreading of parasites in a free-ranging population of Mediterranean mouflon. From the analysis of 433 faecal samples, we found Eimeria spp. and gastrointestinal strongyles (GIS) were the most common parasites (94%). The faecal oocyst counts of Eimeria spp. were the highest during the first years of life. It was 1.6 times higher in females than in males and 2.5 times higher in individuals in poor than in good body condition. Similarly, the faecal egg count of GIS was higher in females and decreased with age, but only in males. Finally, reproductive females had GIS faecal egg count values 2.6 times higher than non-reproductive females. Management strategies of parasites should thus primarily focus on reproductive females and young individuals in poor body condition as they represent the main contamination source of the environment.

Fine‐scale spatial genetic structure of populations results from social and spatial behaviors of individuals such as sex‐biased dispersal and philopatry. However, the demographic history of a given population can override such socio‐spatial factors in shaping genetic variability when bottlenecks or founder events occurred in the population. Here, we investigated whether socio‐spatial organization determines the fine‐scale genetic structure for both sexes in a Mediterranean mouflon (Ovis gmelini musimon × Ovis sp.) population in southern France 60 years after its introduction. Based on multilocus genotypes at 16 loci of microsatellite DNA (n = 230 individuals), we identified three genetic groups for females and two for males, and concurrently defined the same number of socio‐spatial units using both GPS‐collared individuals (n = 121) and visual resightings of marked individuals (n = 378). The socio‐spatial and genetic structures did not match, indicating that the former was not the main driver of the latter for both sexes. Beyond this structural mismatch, we found significant, yet low, genetic differentiation among female socio‐spatial groups, and no genetic differentiation in males, with this suggesting female philopatry and male‐biased gene flow, respectively. Despite spatial disconnection, females from the north of the study area were genetically closer to females from the south, as indicated by the spatial analysis of the genetic variability, and this pattern was in accordance with the common genetic origin of their founders. To conclude, more than 14 generations later, genetic signatures of first introduction are not only still detectable among females, but they also represent the main factor shaping their present‐time genetic structure.

Gastro-intestinal nematodes, especially Haemonchus contortus, are widespread pathogenic parasites of small ruminants. Studying their spatial genetic structure is as important as studying host genetic structure to fully understand host-parasite interactions and transmission patterns. For parasites having a simple life cycle (e.g., monoxenous parasites), gene flow and spatial genetic structure are expected to strongly rely on the socio-spatial behavior of their hosts. Based on five microsatellite loci, we tested this hypothesis for H. contortus sampled in a wild Mediterranean mouflon population (Ovis gmelini musimon × Ovis sp.) in which species- and environment-related characteristics have been found to generate socio-spatial units. We nevertheless found that their parasites had no spatial genetic structure, suggesting that mouflon behavior was not enough to limit parasite dispersal in this study area and/or that other ecological and biological factors were involved in this process, for example other hosts, the parasite life cycle, or the study area history.Le comportement socio-spatial de l’hôte conduit-il à une structure génétique à fine échelle de ses parasites ?Les nématodes gastro-intestinaux, et plus particulièrement Haemonchus contortus, sont cosmopolites et pathogènes chez les petits ruminants. Étudier leur structure génétique spatiale est aussi important que d’étudier celle des hôtes pour pleinement comprendre les interactions hôtes-parasites et les processus de transmission. Pour les parasites ayant des cycles de vie simples (par exemple, les parasites monoxènes), on s’attend à ce que les flux de gènes et la structure génétique spatiale dépendent fortement du comportement socio-spatial de leurs hôtes. En utilisant cinq loci microsatellites, nous avons testé cette hypothèse pour des H. contortus échantillonnés dans une population sauvage de mouflons méditerranéens (Ovis gmelini musimon × Ovis sp.) dans laquelle les caractéristiques de l’espèce et de l’environnement génèrent des unités socio-spatiales. Nous avons néanmoins mis en évidence que leurs parasites ne présentent pas de structure génétique spatiale, ce qui suggère que le comportement des mouflons ne restreint pas la dispersion des parasites dans cette aire d’étude et/ou que d’autres facteurs biologiques et écologiques tels que d’autres hôtes, le cycle de vie du parasite, ou l’histoire de l’aire d’étude jouent un rôle dans ce processus.

Background The distinction between lineages of neotropical bats from the Pteronotus parnellii species complex has been previously made according to mitochondrial DNA, and especially morphology and acoustics, in order to separate them into two species. In these studies, either sample sizes were too low when genetic and acoustic or morphological data were gathered on the same individuals, or genetic and other data were collected on different individuals. In this study, we intensively sampled bats in 4 caves and combined all approaches in order to analyse genetic, morphologic, and acoustic divergence between these lineages that live in the same caves in French Guiana. Results A multiplex of 20 polymorphic microsatellite markers was developed using the 454-pyrosequencing technique to investigate for the first time the extent of reproductive isolation between the two lineages and the population genetic structure within lineages. We genotyped 748 individuals sampled between 2010 and 2015 at the 20 nuclear microsatellite loci and sequenced a portion of the cytochrome c oxydase I gene in a subset of these. Two distinct, non-overlapping haplogroups corresponding to cryptic species P. alitonus and P. rubiginosus were revealed, in accordance with previous findings. No spatial genetic structure between caves was detected for both species. Hybridization appeared to be quite limited (0.1–4%) using microsatellite markers whereas introgression was more common (7.5%) and asymmetric for mitochondrial DNA (mtDNA). Conclusions The extremely low rate of hybridization could be explained by differences in life cycle phenology between species as well as morphological and acoustical distinction between sexes in one or the other species. Taken together, these results add to our growing understanding of the nature of species boundaries in Pteronotus parnelli, but deserve more in-depth studies to understand the evolutionary processes underlying asymmetric mtDNA introgression in this group of cryptic species. Electronic supplementary material The online version of this article (10.1186/s12862-018-1289-8) contains supplementary material, which is available to authorized users.

In natural populations, gene flow often represents a key factor in determining and maintaining genetic diversity. In a worldwide context of habitat fragmentation, assessing the relative contribution of landscape features to gene flow thus appears crucial for sustainable management of species. We addressed this issue in Mediterranean mouflon (Ovis gmelini musimon × Ovis sp.) by combining previous knowledge on behavioral ecology with landscape genetics. We also assessed how sex-specific behavioral differences translated in term of functional connectivity in both sexes. We relied on 239 individuals genotyped at 16 microsatellite markers. We applied a model optimization approach in a causal modeling framework of landscape genetics to test for the effects on gene flow of habitat types and linear landscape features previously identified as important for movements and habitat selection in both sexes. Five resistance values were alternately assigned to these landscape characteristics leading to a comprehensive set of resistance surfaces. Isolation by resistance shaped female gene flow, supporting the central role of linear landscape features as behavioral barriers for animal movements. Conversely, no isolation by resistance was detected in males. Although a lack of statistical power cannot be discarded to explain this result, it tended to confirm that males are less influenced by landscape structures during the mating period. Combining previous knowledge on behavioral ecology with results from landscape genetics was decisive in assessing functional landscape connectivity in both sexes. These results highlighted the need to perform sex-specific studies for management and conservation of dimorphic species.

National audience

Resilience capacities of hydrothermal vent species are largely dependent on their dispersal abilities. Characterizing gene flow and identifying biotic and/or abiotic factors impacting population exchanges are thus of prime importance. In this study we focused on Peltospira smaragdina, a gastropod species inhabiting hydrothermal vent chimneys along the Mid-Atlantic Ridge (MAR). We genotyped 237 individuals from 6 hydrothermal fields (23°N to 45°N) at 12 522 SNPs using a double-digest restriction-site associated DNA sequencing (ddRAD). Using population genetics clustering approaches, three genetic groups were detected. These groups corresponded to the Moytirra vent field, fields of the Azorean triple junction, and the deeper sites of TAG, Snake-Pit and Broken-Spur. Fst values were in accordance with such results. Half of the individuals of Rainbow were however more related to the third and most southern group. Ancestry coefficient confirmed local admixture between the Lucky-Strike and TAG/Snake-Pit/Broken-Spur genetic clusters at Rainbow. These results indicated that (1) gene flow is greatly impeded between Moytirra and the other fields sampled, (2) TAG, Snake-Pit and Broken-Spur may be panmictic, and (3) the Rainbow field may represent a putative ‘hybrid’ zone receiving migrants from TAG/Snake-Pit/Broken-Spur at a rather low rate. Several hypotheses might explain genetic breaks between vent fields, such as the presence of topographical barriers (fracture zones) or decreasing depth near to the Azorean Triple Junction. Genetic differences observed along the MAR between Peltospira smaragdina and other species highlighted the need of performing comparative studies on several species having contrasted life-history traits, as planned in the iAtlantic WP1.