Génomique de la spéciation chez le Grand Corégone (Coregonus clupeaformis) : caractérisation des bases génomiques associées à la différenciation phénotypique

Authors: Rougeux, Clément
Advisor: Bernatchez, LouisGagnaire, Pierre-Alexandre
Abstract: Repeated evolution of phenotypic differentiation between diverging species pairs provides an ideal context for the study of the genomic architecture of parallel speciation. The main objective of this thesis is to provide evidence concerning the genomic bases involved in phenotypic differentiation, and their influence on the evolutionary potential of species complexes belonging to two related lineages, the Lake Whitefish (Coregonus clupeaformis) and European Whitefish (C. lavaretus). Specificaly, it is necessary to elucidate the origin of the genetic polymorphism of each population from both whitefish lineages, and to which extend this polymorphism was involved in the genetic divergence and phenotypic differentiation between species pairs. A genome-wide analysis allowed to infer the divergence history combining the effects of historical demograhy and selective pressure that collectively shape the genomic landscape of differentiation between species pairs. Then, transcriptomic analyses revealed parallel polygenic bases involved in the phenotypic differentiation of species pairs, and such genes were enriched in shared ancestral polymorphism. Finaly, a parallel differential methylation level has been identified between species. Although this methylation is genomicaly based, these differentially methylated regions are associated with a transcriptional differentiation between the limnetic and benthic species. This work shows that selection is constrained by some genotypes which could lead to an independent parallel phenotypic aquisition, but also act on the maintainance of ancestral genetic polymorphism, particularly in a context of parallel speciation. This thesis allows to highlight and to contribute to the understanding of the genomic mechanisms generating biodiversity, notably by using an integrative approach.
Document Type: Thèse de doctorat
Issue Date: 2019
Open Access Date: 16 April 2019
Permalink: http://hdl.handle.net/20.500.11794/34461
Grantor: Université Laval
Collection:Thèses et mémoires

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