Title: Faces That Only an Expert Could Love: Mechanisms of Adaptive Craniofacial Evolution in Phyllostomid Bats
Abstract: The New World Leaf-Nosed bats (phyllostomids) are a diverse group of dietary specialists within mammals. From an insectivorous ancestor, they have evolved to specialize on soft-bodied insects, hard-bodied insects, fish, other small vertebrates (lizards, mice), nectar, fruit, blood or a combination of food sources. In this thesis, I explore the evolutionary and developmental origins of bat-specific craniofacial morphologies using anatomical, cellular, and developmental genetics approaches. This work highlights the diversity of bats, reflected on their craniofacial evolution and development. In Chapter 1, I compare patterns of neotropical bat skull shape changes during evolution and development with 3D imaging and morphometrics. In Chapter 2, I quantify cellular proliferation and spatial distribution during craniofacial development to evaluate its relationship to the diversity of facial length differences. In Chapter 3, I utilize morphometrics and quantitative fluorescence image analysis of cranial neural crest cell (CNC) dynamics across species. In Chapter 4, I characterize mice genetically altered in a key signaling pathway found to vary in bat CNC derivatives, the bone morphogenetic protein (BMP). I quantify the changes to the head of the mice and relate these craniofacial geometries back to the facial changes between bat species. Combined, this thesis identifies major sources of morphological variation of head form in bats, a group flying mammals representing one of the greatest transformations in vertebrate evolution.
Committee: Hopi Hoekstra (Advisor), Cliff Tabin (HMS, Advisor), Arkhat Abzhanov (Imperial College London), James Hanken, Elena Kramer, Mansi Srivastava