PARENT SESSION
Oral Session #23: Animal Ecology: Behavior and Sociobiology. Presiding: P. Brunkow.
Tuesday, August 7, 2001. 8:00 AM to 11:45 AM. Hall of Ideas E.
Locomotor performance and social dominance in male Anolis cristatellus (Reptilia: Sauria).
Perry, Gad1, LeVering, Kate2, Girard, Isabelle1, Garland, Theodore1, 1 2
ABSTRACT- Physiological performance capacity affects Darwinian fitness when it influences survival or reproduction. A priori, various aspects of locomotor performance might be expected to influence success in prey capture, escape from predators, territoriality, and mate acquisition. However, the relationship between individual variation in locomotor performance and components of Darwinian fitness has rarely been examined. We used Anolis cristatellus to test the hypothesis that male social dominance is determined, in part, by locomotor capability. Males in this species aggressively defend a territory, and territorial fights can last > 40 min. Adult male lizards were observed and then collected in the British Virgin Islands. After capture, we measured maximal sprint running speed as the fastest 0.25 m interval when chased along a 2.5-m, photocell-lined race track. Endurance was measured as the time to fatigue on a motorized treadmill moving at 0.3 km/hr. Pairs of males of similar size were then placed in an arena, and the ensuing interaction was observed until a resolution was reached. Winners had significantly higher endurance (mean = 300 vs. 268 sec; N = 72 pairs, paired-t = 2.72, 1-tailed p = 0.004), and during the interaction showed more behaviors indicative of dominance than did losers (mean dominance score of 7.1 vs. 0.6, N = 52 pairs, t = 7.30, p < 0.001). Endurance was positively correlated with the number of assertion displays made prior to capture (N = 50, Pearson correlation coefficient = 0.29, 1-tailed p = 0.021). In addition, animals that won fights had displayed more often in nature, prior to capture, than did losers (0.21 vs. 0.06 displays/min; df = 33, t = 1.94, 1-tailed p = 0.033). Thus, laboratory-measured endurance, but not maximal sprint speed, predicts social dominance and field display rates in male A. cristatellus.
KEY WORDS: Anolis cristatellus, locomotor physiology, social dominance, field behavior