Evidence of landscape-driven repeated adaptation among 13 Eucalyptus 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 may occur similarly across species. Identifying repeated adaptation across species increases statistical power to determine causal genes driving adaptation and reveals insights into the nature of evolution. These types of insights could have theoretical and applied applications, particularly as the climate continues to change. We interrogate repeated molecular adaptation across 13 eucalypt species. In total, we found 38 candidate genes with shared putatively adaptive signals in as many as 12 species. This suite of genes contains important functions, including myeloblastosis (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 further evidence that repeated adaptation can occur among orthologs, which may play a consistent role in local adaptation.