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Histoire évolutive et influence de la sélection sur la diversité génétique des annélides polychètes d’environnements extrêmes

Abstract : The question of the variable environments available for a given population has been raised in the past. Levene (1953) sought to see to what extent it is possible to maintain polymorphism in a situation where more than one ecological niche is available. Subsequently, other authors looked for the conditions (selective pressures, niche size, etc.) in which a spatially variable environment, i.e. an environment grouping several niches, could induce or maintain polymorphism. On the other hand, the intrinsic variability of the environment, and therefore the effect it has on the species exposed to it, is little studied. This thesis has been able to highlight the power of environmental variability on the maintenance of spontaneous or introgressed polymorphism in populations. Thus, differences in environmental variability between populations of the same species imply the development of adaptations and can generate and reinforce the differentiation between populations. Along with the life history traits and genetic background of the species, this variability marks the genome and leaves footprints of the environments characterized, among other things, by a contrasting thermal variability. It also induces different and more or less strong selective pressures on enzymatic systems. These selective pressures lead to the implementation of different strategies depending on the species that must make the most of the possibilities offered by their ancestral enzymatic baggage.
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Submitted on : Wednesday, February 5, 2020 - 12:25:09 PM
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Alexis Bioy. Histoire évolutive et influence de la sélection sur la diversité génétique des annélides polychètes d’environnements extrêmes. Biologie moléculaire. Sorbonne Université, 2018. Français. ⟨NNT : 2018SORUS156⟩. ⟨tel-02467893⟩

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