A Map of Local Adaptation in <i>Arabidopsis thaliana</i>

TLDR

Local adaptation is critical for species persistence in the face of rapid environmental change, but its genetic basis is not well understood. Growing Arabidopsis thaliana in field experiments at four sites across its native range, we identified candidate loci for local adaptation through a genome‑wide association study of lifetime fitness in geographically diverse accessions. Fitness‑associated loci exhibited geographic and climatic signatures of local adaptation, with high‑fitness alleles clustering near the sites where they confer advantage and occupying distinct climate spaces, and independent loci of diverse molecular functions driving fitness variation at each site, indicating that distinct genetic mechanisms enable flexible evolutionary responses across the species range.

Abstract

Local adaptation is critical for species persistence in the face of rapid environmental change, but its genetic basis is not well understood. Growing the model plant Arabidopsis thaliana in field experiments in four sites across the species' native range, we identified candidate loci for local adaptation from a genome-wide association study of lifetime fitness in geographically diverse accessions. Fitness-associated loci exhibited both geographic and climatic signatures of local adaptation. Relative to genomic controls, high-fitness alleles were generally distributed closer to the site where they increased fitness, occupying specific and distinct climate spaces. Independent loci with different molecular functions contributed most strongly to fitness variation in each site. Independent local adaptation by distinct genetic mechanisms may facilitate a flexible evolutionary response to changing environment across a species range.