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Mécanismes évolutifs à la base du maintien de la diversité génétique et conséquences adaptatives chez l'isopode terrestre armadillidium vulgare

Abstract : Genetic diversity is a crucial parameter for both populations and individuals. As such, heterozygosity often confers a selective advantage to individuals in numerous taxa, and sexual selection processes can result in an optimisation of offspring heterozygosity. We tested these hypotheses in the terrestrial isopod Armadillidium vulgare. In this work, we highlighted a higher reproductive success for more heterozygous males, which could result from both intrasexual competition and mate choice, as well as a choice for a genetically dissimilar partner. These two processes result in an increase in offspring heterozygosity. Moreover, we described for the first time a high rate of multiple paternity in natural as well as in experimental populations, increasing brood allelic richness and allowing post-copulatory sexual selection processes. Besides, we showed that more heterozygous individuals survive better when confronted to a bacterial infection, probably through a better tolerance. More heterozygous individuals are also bigger at the same age, which is particularly important in females because a big size leads to a higher fecundity. These results suggest that various mechanisms result in genetic diversity maintenance in A. vulgare populations and confer a better fitness to individuals. Thereby, it is likely that populations of this terrestrial isopod possess a high adaptive potential enabling their long-term maintenance.
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Sylvine Durand. Mécanismes évolutifs à la base du maintien de la diversité génétique et conséquences adaptatives chez l'isopode terrestre armadillidium vulgare. Génétique animale. Université de Poitiers, 2017. Français. ⟨NNT : 2017POIT2287⟩. ⟨tel-01980843⟩

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