Amylase copy number analysis in several mammalian lineages reveals convergent adaptive bursts shaped by diet
The amylase gene (AMY), which codes for a starch-digesting enzyme in animals, underwent several gene copy number gains in humans, dogs, and mice, presumably along with increased starch consumption during the evolution of these species. Here we present evidence for additional AMY copy number expansions in several mammalian species, most of which also consume starch-rich diets. We also show that these independent AMY copy number gains are often accompanied by a gain in enzymatic activity of amylase in saliva. We used multi-species coalescent modeling to provide further evidence that these recurrent AMY gene copy number expansions were adaptive. Our findings underscore the overall importance of gene copy number amplification as a flexible and fast adaptive mechanism in evolution that can independently occur in different branches of the phylogeny.