Bat teeth illuminate the diversification of mammalian tooth classes

Tooth classes are an innovation that has contributed to the evolutionary success of mammals. However, our understanding of the mechanisms by which tooth classes diversified remain limited. We use the evolutionary radiation of noctilionoid bats to show how the tooth developmental program evolved during the adaptation to new diet types. Combining morphological, developmental and mathematical modeling approaches, we demonstrate that tooth classes develop through independent developmental cascades that deviate from classical models. We show that the diversification of tooth number and size is driven by jaw growth rate modulation, explaining the rapid gain/loss of teeth in this clade. Finally, we mathematically model the successive appearance of tooth buds, supporting the hypothesis that growth acts as a key driver of the evolution of tooth number and size. Our work reveal how growth, by tinkering with reaction/diffusion processes, drives the diversification of tooth classes and other repeated structure during adaptive radiations. Despite their key role in the evolution of mammals, the origin and diversification of tooth classes (incisors, canines, premolars and molars) remain relatively obscure. Here the authors use integrative approaches to explain the independent evolution and rapid diversification of two tooth classes, premolar and molars, in noctilionoid bats.

Automated summary

Tooth classes are an important factor in the evolutionary success of mammals, but the mechanisms behind their diversification are not well understood. Through the study of noctilionoid bats, researchers have shown how the tooth developmental program evolved during adaptation to different diets. They found that tooth classes develop through independent developmental cascades that deviate from classical models, and that the diversification of tooth number and size is driven by jaw growth rate modulation. Mathematical models also supported the hypothesis that growth plays a key role in the evolution of tooth number and size. This study sheds light on the diversification of tooth classes and other repeated structures during adaptive radiations.