Convergent evolution through independent rearrangements in the primate amylase locus

Structurally complex genomic regions can foster evolutionary convergence by repeatedly generating gene duplications that yield similar expression patterns and traits across lineages. Focusing on the primate amylase locus, we leveraged high-quality genome assemblies from 53 primate species and multi-tissue transcriptomes from Old World monkeys to reconstruct the evolutionary history of recurrent duplications. We show that lineage-specific long terminal repeat retrotransposon insertions may be associated with initial structural instability, while subsequent duplications are primarily driven by non-allelic homologous recombination. Independent duplications in rhesus macaques, olive baboons, and great apes produced distinct amylase copies with convergent expression in pancreas and salivary glands, and it signals episodic diversifying selection, consistent with emerging functional divergence. Our analyses indicate that an ancestral gene with dual pancreas and salivary expression in Catarrhini duplicated in great apes, facilitating subfunctionalization and regulatory rewiring. These findings illuminate how modular structural and regulatory variation drives evolutionary innovation and molecular convergence.