Temperature-associated selection linked to putative chromosomal inversions in king scallop (Pecten maximus)

Abstract

The genomic landscape of divergence¿the distribution of differences amongpopulations or species across the genome¿is increasingly characterized tounderstand the role that microevolutionary forces such as natural selectionand recombination play in causing and maintaining genetic divergence.This line of inquiry has also revealed chromosome structure variation to bean important factor shaping the landscape of adaptive genetic variation.Owing to a high prevalence of chromosome structure variation and thestrong pressure for local adaptation necessitated by their sessile nature,bivalve molluscs are an ideal taxon for exploring the relationship betweenchromosome structure variation and local adaptation. Here, we report apopulation genomic survey of king scallop (Pecten maximus) across its naturalrange in the northeastern Atlantic Ocean, using a recent chromosome-levelgenome assembly. We report the presence of at least three large (12-22 Mb),putative chromosomal inversions associated with sea surface temperatureand whose frequencies are in contrast to neutral population structure.These results highlight a potentially large role for recombination-suppressingchromosomal inversions in local adaptation and suggest a hypothesis toexplain the maintenance of differences in reproductive timing found atrelatively small spatial scales across king scallop populations