NOVELTEETH · Exploring the origin and diversification of mammalian tooth classes

One long-standing question in evolutionary biology is: how do new morphological innovations arise? Integrative advances in palaeontology, genomics, development and evolution have unveiled general principles behind evolutionary novelties. However, we are far from understanding the mechanisms by which novelties emerge from ancestral genomic and developmental programs and then diversify in new ecological contexts. To solve this problem, my research uses the dramatic morphological and ecological diversity of bat teeth as a model system to study the origin and diversification of a major mammalian innovation, the tooth classes. Using morphological, genomic, developmental and modelling approaches on multiple species of bats from various ecological contexts, my goal is to understand the origin of mammalian tooth classes and establish a predictive model to study their evolution. Using geometric morphometric approaches, I will first characterize the differences and unique traits in tooth class morphologies in adults and during ontogeny on CT scans (Aim 1). Then, to link the morphological variation with the underlying changes in the genomic and developmental program, I will establish a developmental transcriptomic signature for each tooth class using Spatial Transcriptomics and MERFISH in multiple species across developmental stages (Aim 2). Finally, I will link these morphological and transcriptomic changes by developing an integrative data-driven model of tooth class evolution using machine learning and extend these models to other mammals (Aim 3). By establishing bat teeth as a unique study system, my research constitutes an integrative framework using natural variation as a starting point to understand the evolution of morphological novelties in various ecological contexts.