Meeting Abstract

103.2  Wednesday, Jan. 7  Artificial Selection, Developmental Constraints, and Craniofacial Variation in the Feral and Domesticated Pigeon (Columba livia) YOUNG, N.M.*; FONDON III, J.W.; University of California, San Francisco; University of Texas at Arlington nathan.m.young@gmail.com

The relative importance of selection and constraint in evolution is one of the oldest questions in biology. While selection determines the fate of alleles, biases in the pattern of variation define selection’s sphere of influence. Observed phenotypic variation consequently is the product of both processes, yet disentangling their relative contributions can be difficult since selection reduces diversity. This discordance between observed and potential variation confounds investigations of developmental constraints, mutation bias, or other factors impacting phenotypic variance. In contrast, organisms often exhibit greater phenotypic variation under domestication, but it is unclear what relationship this variation has to that found in their wild counterparts. Here we hypothesize that domesticated breeds of the common pigeon (Columba livia) represent extensions of variation found in the feral pigeon shape space. To test this hypothesis we compared craniofacial variation in feral pigeons (N=40) to that of 43 domesticated pigeon breeds (N=63) using Principal Components Analysis of 3D shape coordinates acquired by CT. Results reveal that the principal components of variation are essentially identical between feral and domestic pigeons, and that domestic pigeons are effectively exaggerations of the same types of variation appearing in feral pigeons. These results suggest that domestic pigeon breeds represent a high signal-to-noise system that is a potentially powerful model for measuring morphological covariance and constraint by enabling the dissection of the basic axes of natural craniofacial variation.