Evidence of landscape-driven repeated adaptation among 13 tree species

Local adaptation is the biological process by which native populations become more fit. Intraspecific patterns of local adaptation occur through shifts in allele frequency within or near genes and there is uncertainty in measuring intraspecific local adaptation through genotype-environment associations because of biological and statistical limitations. However, recent work shows that interspecific replicated adaptive signals provide greater confidence to these correlative approaches. We interrogate repeated molecular adaptation across 13 eucalypt species. In total, we found 38 genes with shared adaptive signals in at least 7 species. This suite of genes contains important functions, including MYB proteins, acyl-CoA dehydrogenases and Leucine-rich kinases. Species with restricted and widespread geographical distributions shared putative patterns of adaptation, and phylogenetic closeness did not increase patterns of repeated adaptation compared to geographic overlap. This work provides startling evidence that repeated adaptation can occur among homologs with conserved functions, which may play a consistent role in adaptation.