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Microévolution des déterminismes sexuels chez le poIsson Tétra Méxicain, Astyanax mexicanus

Abstract : Sex determining (SD) mechanisms in teleost fishes have been investigated mainly at a macro-evolutionary scale highlighting a high turnover of master SD genes and their associated sex chromosomes. Interestingly, in addition to the A chromosomes, supernumerary B chromosomes (Bs) have been detected in a number of species and even associated as sex chromosomes in some of them. As such, my thesis project aimed to investigate SD mechanisms evolution with respect to these Bs in the Mexican tetra, Astyanax mexicanus, in which many blind cave populations (CF) are known to have evolved from a surface ancestral population (SF) less than 20,000 years. Our results provide functional evidences for the existence of an "unusual" SD system relying solely on male-dominant "B-sex" chromosomes with the gdf6b-B gene as a potential MSD gene in the Pachón CF. Furthermore, we also provide results suggesting a rapid evolutionary transition from a fixed male-dominant B-sex chromosome-type system in some populations toward a complex (probably polygenic) SD system relying only partly on the B-sex chromosome and their gdf6b-B loci in other populations.
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Submitted on : Monday, April 12, 2021 - 11:01:48 AM
Last modification on : Thursday, August 5, 2021 - 3:43:27 AM


  • HAL Id : tel-03195853, version 1



Boudjema Imarazene. Microévolution des déterminismes sexuels chez le poIsson Tétra Méxicain, Astyanax mexicanus. Sciences du Vivant [q-bio]. Université de Rennes 1 (UR1), FRA., 2020. Français. ⟨tel-03195853⟩



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