Exploring mechanisms of lateral gliding membrane development in bats

Abstract

A central goal of evolutionary developmental biology is understanding how genetic changes lead to phenotypic variation over evolutionary time. Studying traits that have evolved multiple times in different lineages is a powerful way to dissect this genotype-phenotype relationship and understand how genome evolution instructs changes in gene expression, cell behavior, and tissue morphogenesis. One such recurrently evolved trait is the mammalian lateral gliding membrane, or patagium, a structure that has independently evolved up to seven times in mammals and has been instrumental in their novel abilities of gliding and flying. Among mammals with patagia, only bats have taken this adaptation beyond gliding to achieve true self-powered flight. Previous research on the molecular basis for the formation of the patagium in marsupial sugar gliders identified several upregulated genes and rapidly evolving regulatory elements active in the developing patagium. However, no research has been conducted in bat tissue to characterize the regulatory basis for its formation. This project uses field dissected bat tissue to identify regulatory regions and coding genes associated with patagium evolution and development. Using transcriptome and epigenome sequencing, computational analyses, and functional tests, I have identified a lineage-specific enhancer in the locus of CREB5–a patagium-upregulated gene that is enriched for rapidly evolving regulatory elements. Thus, investigating the molecular mechanisms underlying patagium development has allowed for an enhanced understanding of how cis-regulatory elements evolve to produce novel, specialized traits.