Behavioral Ecology Advance Access originally published online on October 22, 2009
Behavioral Ecology 2009 20(6):1334-1342; doi:10.1093/beheco/arp136
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Why are females ornamented? A test of the courtship stimulation and courtship rejection hypotheses
a Department of Zoology, University of Melbourne, Melbourne, Victoria 3010, Australia b Department of Wildlife Conservation and Science, Zoos Victoria, Parkville, Victoria 3052, Australia
Address correspondence to D. Stuart-Fox. E-mail: devis{at}unimelb.edu.au.
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Abstract |
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Female ornamentation was initially thought to reflect genetic correlation with the more elaborate male trait. However, this cannot explain female-specific ornamentation, such as the conspicuous coloration displayed by females of many species during breeding. Females may exhibit distinctive, reproductive coloration to 1) advertise receptivity and stimulate male courtship or 2) advertise nonreceptivity when gravid to reduce male courtship, harassment, and potentially costly copulations. We tested both hypotheses in the Lake Eyre dragon lizard (Ctenophorus maculosus) by quantifying female coloration, using spectroradiometry and a model of lizard color perception, and male and female behavior across the female reproductive cycle. Females develop bright orange coloration on their throat and abdomen during the breeding season, whereas males remain cryptically colored. The onset of orange coloration was associated with enlarging follicles, acceptance of copulations, and escalation of male courtship. Rather than fading once females were no longer receptive, however, the intense orange coloration remained until oviposition. Furthermore, despite maximal coloration associated with nonreceptivity, males persisted with courtship and copulation attempts, and females increased rejection behaviors comprising lateral displays and flipping onto their backs (to prevent forced intromission), both of which emphasize the conspicuous ventrolateral coloration. These apparently costly rejection behaviors did not reduce male harassment but did decrease the frequency of potentially costly copulations. These results suggest that 1) males do not determine female receptivity based on coloration alone and 2) the potentially costly rejection behaviors may have evolved to reduce the direct costs of mating.
Key words: color perception, cost of mating, female resistance, lizard, reproduction, sexual conflict, visual modeling.
Received 4 September 2008; revised 29 June 2009; accepted 19 July 2009.