Annuaire
Flora BORNE, IBENS Paris
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Le 11/09/2026, de 11:00 à 12:00 |
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| S'adresser à | Equipe Pantalacci Sémon, Salle des Thèses |
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The fate of a mutation depends on the genetic background in which it arises. Yet, what makes a background permissive for adaptive mutations remains poorly understood. We address this question using the evolution of cardiotonic steroid resistance in the Na⁺/K⁺-ATPase of Drosophila subobscura. D. subobscura naturally harbors both sensitive and resistant alleles. Using functional assays, population genetics, and genetic engineering, we show that resistant substitutions causing severe defects in the closely related species D. melanogaster are tolerated in D. subobscura. This robustness likely arises from a limited number of lineage-specific substitutions distributed across the protein sequence that buffer the negative effects of resistant substitutions. Our results demonstrate how historical contingency shapes the accessibility of adaptive evolution.