Table of Contents
International Journal of Evolutionary Biology
Volume 2011 (2011), Article ID 423938, 16 pages
http://dx.doi.org/10.4061/2011/423938
Research Article

A Macroevolutionary Perspective on Multiple Sexual Traits in the Phasianidae (Galliformes)

Department of Biology, University of Florida, P.O. Box 118525, Gainesville, FL 32611, USA

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.

Abstract

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. Even with this limitation, when the predictions of these alternative models were compared with the heterogeneous patterns of evolution of dimorphism in phasianids, it is clear that many different selective processes have been involved in the evolution of sexual signals in this group.