Interactive effects of sex and temperature on locomotion in reptiles.

Males and females from several animal taxa differ in locomotor performance traits such as sprinting and jumping. These performance dimorphisms may be explained at least partially by sexual differences in physiology or morphology. In ectotherms such as reptiles, however, thermal ecology places an additional constraint on realized locomotor performance. I review recent studies on reptiles examining sexual differences in locomotor capacity and related thermoregulatory behavior, and discuss potential causes, constraints, and selective pressures that might drive intersexual divergence in capacity for locomotor performance in reptiles. In several cases where such differences occur, sexual dimorphisms in body size do not account for all the observed variation in performance. However, while sex-specific locomotor capacities might be evident in the laboratory, ecological performance in nature is likely the result of complex interactions among sex, thermal sensitivity, habitat type, and behavioral locomotor compensation. Results from laboratory studies of dimorphisms in maximum locomotor capacity are therefore likely to be poor predictors of realized ecological differences in performance. Nonetheless, sex differences in performance are potentially important modifiers of male and female behavioral strategies and overall fitness, and consequently are deserving of more attention than they have thus far received.