Convergent Evolution and Predictability of Gene Copy Numbers Associated with Diets in Mammals

Convergent evolution, the evolution of the same or similar phenotypes in phylogenetically independent lineages, is a widespread phenomenon in nature. If the genetic basis for convergent evolution is predictable to some extent, it may be possible to infer organismic phenotypes and the capability of organisms to utilize new ecological resources based on genome sequence data. While repeated amino acid changes have been studied in association with convergent evolution, relatively little is known about the potential contribution of repeated gene copy number changes. In this study, we explore whether gene copy number changes of particular gene families are linked to diet shifts in mammals and assess whether trophic ecology can be inferred from the copy numbers of a specific set of gene families. Using 86 mammalian genome sequences, we identified 24 gene families with a trend toward higher copy numbers in herbivores, carnivores, and omnivores, even after phylogenetic corrections. We were able to confirm previous findings on genes such as amylase, olfactory receptors, and xenobiotic metabolism genes, and identify novel gene families whose copy numbers correlate with dietary patterns. For example, omnivores exhibited higher copy numbers of genes encoding regulators of translation. We also established a discriminant function based on the copy numbers of 13 gene families that can help predict trophic ecology to some extent. These findings highlight a possible association between convergent evolution and repeated copy number changes in specific gene families, suggesting the potential to develop a method for predicting animal ecology from genome sequence data.