Pseudogenes Point to Protracted Evolutionary Regression of Oral Anatomy in Myrmecophagous Mammals
Myrmecophagous species are characterized by striking convergent morphological adaptations such as skull elongation, enlargement of salivary glands that produce viscous saliva, and long claws to dig into ant and termite nests. To gain insights into the molecular adaptations underlying the regression of these morpho-anatomical traits, we investigated the functionality of a candidate set of dental (ACP4, AMBN, AMELX, AMTN, DSPP, ENAM, MMP20, ODAM, ODAPH, KLK4), gustatory (TAS1R1, TAS1R2, TAS1R3, PKD2L1), and masticatory (MYH16) genes in mammalian species representing at least nine independent adaptations to myrmecophagy. The combined evidence suggests that the convergent evolution of myrmecophagy has occurred as a protracted process with distinct phases of anatomical evolution, over timescales as long as 60 million years.