HUSAK, J. F.; LAPPIN, A. K.; Oklahoma State University; Northern Arizona University: A strong bite increases the mating success of collared lizards

In territorial, polygynous taxa, individual variation in territory quality and mating success are expected to reflect individual variation in underlying morphological, physiological, and whole-animal performance traits. We studied a highly territorial, polygynous lizard (Crotaphytus collaris) that uses its jaws as a weapon in territorial interactions to test the hypothesis that bite-force performance is a more important determinant of potential fitness than body or weapon (i.e., head) size. Among territorial male collared lizards, bite force was a powerful predictor of both territory area and estimates of annual mating success. Body and head size were not correlated with these estimates of fitness or with bite-force performance. Therefore, bite-force performance is potentially a causal agent that determines the fitness of adult male collared lizards, whereas body and weapon size are not. Females and yearling males, which do not defend territories, exhibited no significant correlations between home range area and bite force. The implication of these results for polygynous, territorial species is that sexual selection acts upon variation in highly relevant performance characteristics rather than on variation in specific morphological features. Weapon performance, rather than weapon size, affects fitness by shaping the outcome of agonistic interactions among competing males, and territory quality may be based on the outcomes of actual confrontations rather than on characters associated with displays. Displays performed during territory maintenance function as reminders of earlier encounters. When weapons have the potential to inflict costly injuries, displays that advertise honest signals of fighting ability may approach weapon performance in predicting potential fitness.