Meeting Abstract

122-8  Sunday, Jan. 7 11:45 – 12:00  Evolution of Avian Egg Shape: Morphospace, Mechanics and Flight STODDARD, MC*; YONG, EH; AKKAYNAK, D; SHEARD, C; TOBIAS, J; MAHADEVAN, L; Princeton University; Nanyang Technical University; Interuniversity Insitute of Marine Sciences; University of Bristol; Department of Life Sciences, Imperial College London; Harvard University mstoddard@princeton.edu

Why do eggs come in so many different shapes, from the near-spherical eggs of owls to the pointy eggs of guillemots? We currently lack a global synthesis of how and why egg shape differences evolve. We applied morphological, mechanistic and macroevolutionary analyses to the egg shapes of 1400 bird species. We quantified egg-shape diversity in terms of two variables, asymmetry and ellipticity, allowing us to map the observed morphologies in a two-dimensional morphospace. We then developed a simple mechanical model that can explain the observed diversity of egg shapes. In our model, we suggest that it is the egg’s stretchy membrane and not the hard shell that is responsible for differences in egg shape. Using phylogenetic models, we demonstrated that egg shape is correlated with flight ability on a broad taxonomic scale. Adaptations for flight may have had a powerful effect on egg-shape variation in birds.