Meeting Abstract

P1.207  Friday, Jan. 4  Uncovering the morphological and developmental basis of vane asymmetry in flight feathers FEO, TJ*; PRUM, RO; Yale University; Yale University teresa.feo@yale.edu

Asymmetric flight feathers represent a novel innovation during the evolution of feathers as well as flight in birds. Asymmetric flight feathers are characterized by asymmetry in the width of the vanes that make up either side of the feather; the leading vane with respect the airflow is typically less than half the width of the trailing vane. The leading and trailing vanes are each comprised of a series of branches termed barbs, and it is therefore differences in barb morphology that produce the overall vane asymmetry. Over the past century researches have observed a variety of morphological differences between leading and trailing barbs, such as differences in barb angle or length, that could each contribute to vane asymmetry. However, there has been no comprehensive description of how each of these morphological differences contribute to the overall vane asymmetry within an individual feather, or how these differences are produced during the development of a feather. We describe the major features of barb morphology that contribute to vane asymmetry and describe when these features arise during the development of adult outer tail feathers from two parrot species. This study provides a detailed account of the specific developmental and morphological modifications that must have occurred during the evolution of asymmetric feathers.