Le bouquetin des Alpes : pas forcément tiré d’affaire
Espèce réintroduite au XIXe siècle, le bouquetin des Alpes n’est plus menacé d’extinction selon l’IUCN (Union internationale pour la conservation de la nature). Or, ce constat ne tient pas compte de risques d’ordre génétique, indiquent des biologistes de l’Université de Neuchâtel. Dans la revue Nature Communications de ce jour, Daniel Croll et ses collègues soulignent qu’on ne peut écarter le risque d’extinction en se basant uniquement sur un nombre minimal d’individus censés suffire à perpétuer l’espèce.
Publication
Grossen C, Guillaume F, Keller LF, Croll D,
Purging of highly deleterious mutations through severe bottlenecks in ibex.
Nature Communications. DOI: 10.1038/s41467-020-14803-1.
Disponible librement sur : www.nature.com/ncomms, https://www.nature.com/articles/s41467-020-14803-1
→ Dr. Daniel Croll est professeur à l'institut de biologie à l'université de Neuchâtel. Il est membre du Swiss Plant Science Web.
Abstract in English
Human activity has caused dramatic population declines in many wild species. The resulting bottlenecks show a profound impact on the genetic makeup of a species with unknown consequences for health. A key genetic factor for species survival is the evolution of deleterious mutation load. However, to date, we lack empirical evidence on how bottleneck strength and mutation load interact. We analyze 60 complete genomes of six ibex species and the domestic goat. We show that historic bottlenecks rather than the current conservation status predict levels of genome-wide variation. By analyzing the exceptionally well-characterized population bottlenecks of the once nearly extinct Alpine ibex, we find genomic evidence of concurrent purging of highly deleterious mutations but accumulation of mildly deleterious mutations. This suggests that recolonization bottlenecks induced both relaxed selection and purging, thus reshaping the landscape of deleterious mutation load. Our findings highlight that even populations of ~1000 individuals can accumulate mildly deleterious mutations. Conservation efforts should focus on preventing population declines below such levels to ensure long-term survival of species.