SOCIAL BEHAVIOR OF TWO SPECIES OF CHAMELEONS IN MADAGASCAR: INSIGHTS INTO SEXUAL SELECTION

Signaling plays a critical role in social behavior, particularly in polygynous systems where males compete with rival males and use signals to attract males. We quantified visual signals and social behavior in two previously unstudied species of chameleons in Madagascar, Furcifer labordi and F. verrucosus. Females of both species displayed distinct color patterns that signaled either nonreceptivity, or potential sexual receptivity. Nonreceptive females rejected all male courtship. Potentially receptive F. verrucosus females mainly allowed males to attempt copulation, whereas potentially receptive F. labordi females were selective. We found that the fleshy, paddle-like rostral appendage in F. labordi was used only, during courtship, whereas other studies showed that hard, keratinized appendages were used for male combat. During male-male contests, F. labordi had much more physically, intense encounters, possibly, to assess opponent quality more accurately since adult Male F. labordi were significantly more size-matched than adult male F. verrucosus. Our study elucidated the role of social signals in these species, illustrated the atypical social behavior of chameleons compared to other lizards, and provided testable hypotheses to further delineate sexual selection in this understudied group. Sexual selection, especially intersexual selection, appears more likely in F. labordi than in F. verrucosus.