Meeting Abstract
99.5 Sunday, Jan. 6 The Homology of Feathers and Scales: Using New High-throughput Methods to Address a Classic Question MUSSER, JM*; WAGNER, GP; PRUM, RO; Yale University; Yale University, Yale Systems biology Institute; Yale University, Peabody Museum of Natural History jacob.musser@yale.edu
Feathers are an important anatomical innovation that evolved in the ancestors of birds and facilitated the evolution of flight, greater thermoregulation, and other facets of modern avian life. However, the molecular basis for the evolution of feathers is poorly understood, and the homology of feathers to other skin derivatives, especially scales, remains contentious. Here, we take a new approach to answering these questions by comparing transcriptomes from different stages of developing feathers, different avian and reptilian scales, and claws. We performed mRNA-seq on different stages of skin appendage development collected from two distantly related birds, Chicken (Gallus gallus) and Emu (Dromaius novaehollandiae), and from American Alligator (Alligator mississippiensis), a member of the extant clade most closely related to birds. Comparison of these transcriptomes allows us to investigate the homology of feathers and scales at different developmental stages. Further, they allow us to identify candidate regulatory molecules, including transcription factors and members of signaling pathways, which underlie feather novelty. Finally, to complement our transcriptome data, we used immunohistochemistry to compare patterns of expression and subcellular localization of the transcription cofactor &beta-catenin, the earliest known molecule expressed in feathers. Our preliminary evidence suggests &beta-catenin is also present in early developing avian scales and alligator scales, suggesting these skin appendages use similar molecular pathways at the beginning of their development. Together, our data presents a new and comprehensive look at the homology of feathers and scales and the molecular basis of feather novelty.
