The role of size and aggression in intrasexual male competition in a social lizard species, Egernia whitii
McEvoy, J and While, GM and Sinn, DL and Wapstra, E, The role of size and aggression in intrasexual male competition in a social lizard species, Egernia whitii, Behavioral Ecology and Sociobiology, 67, (1) pp. 79-90. ISSN 0340-5443 (2013) [Refereed Article]
Competition between males is a key component of the agonistic intrasexual interactions that influence resource acquisition, social system dynamics, and ultimately reproductive success. Sexual selection theory predicts that traits that enhance success in intrasexual competition (particularly male–male competition) should be favored. In vertebrates, this often includes body size and aggression, with larger and/or more aggressive males outcompeting smaller
or less aggressive conspecifics. The majority of studies consider aggression as a flexible trait which responds to local social or environmental conditions. However, aggression frequently shows considerable within-individual consistency
(i.e., individuals have identifiable aggressive behavioral types). Little is known about how such consistency in aggression may influence competition outcomes. We integrated a detailed field study with a laboratory experiment
to examine how a male’s aggressive phenotype and his size influence competitive interactions in Egernia whitii, a social lizard species which exhibits strong competition over resources (limited permanent shelter sites and basking sites). Individual aggression and size did not predict competition outcome in the laboratory nor did they predict home range size, overlap, or reproductive success in the field. However, winners of laboratory trial contests maintained
consistent aggressive phenotypes while consistency in aggression was lost in losers. We suggest that aggression may be important in other functional contexts, such as parental care, and that alternative traits, such as fighting experience, may be important in determining competition outcome in this species.
intrasexual male competition, personality, aggression, lizard, behavioral consistency, behavioral plasticity