SAGE-Hindawi Access to Research International Journal of Evolutionary Biology Volume 2011, Article ID 423938, 16 pages doi:10.4061/2011/423938 Research Article A Macroevolutionary Perspective on Multiple Sexual Traits in the Phasianidae (Galliformes) Rebecca T. Kimball, Colette M. St. Mary, and Edward L. Braun Department of Biology, University of Florida, P.O. Box 118525, Gainesville, FL 32611, USA Correspondence should be addressed to Rebecca T. Kimball,
[email protected]fl.edu Received 2 October 2010; Accepted 26 February 2011 Academic Editor: Rob Kulathinal Copyright © 2011 Rebecca T. Kimball et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Traits involved in sexual signaling are ubiquitous among animals. Although a single trait appears sufficient to convey information, many sexually dimorphic species exhibit multiple sexual signals, which may be costly to signalers and receivers. Given that one signal may be enough, there are many microevolutionary hypotheses to explain the evolution of multiple signals. Here we extend these hypotheses to a macroevolutionary scale and compare those predictions to the patterns of gains and losses of sexual dimorphism in pheasants and partridges. Among nine dimorphic characters, including six intersexual signals and three indicators of competitive ability, all exhibited both gains and losses of dimorphism within the group. Although theories of intersexual selection emphasize gain and elaboration, those six characters exhibited greater rates of loss than gain; in contrast, the competitive traits showed a slight bias towards gains. The available models, when examined in a macroevolutionary framework, did not yield unique predictions, making it difficult to distinguish among them.