Social costs and development of nuptial coloration in male Psammodromus algirus lizards: an experiment

In the lizard Psammodromus algirus, larger and older males show orange nuptial coloration on most of the head and are dominant over smaller and younger, albeit sexually mature, males which do not show such extensive nuptial coloration. This raises the question of why young, small males delay the development of nuptial coloration until a later breeding season. We tested the hypothesis of social costs by manipulating the color of the head of small males. The results of agonistic interactions suggested that small males may pay a cost in terms of being punished by large males. Small males with heads painted orange were still recognized as small by other small males, suggesting that they would not gain in social status relative to normal, dull, small males. We also manipulated the coloration of large males. Small males showed a similar response toward all large males, independent of coloration. This suggests that in short-distance communication, males used other cues, such as body size and behavior, when judging fighting ability. In staged experiments without male competition, female acceptance of matings was influenced by male body size but not by coloration because large males were more successful in obtaining matings than were small males, and within each age/size category there was no difference in mating success between experimental and control males. Key words: lizards, mating success, nuptial coloration, Psammodromus algirus, signals, social status. (Behav Ecol 10:396- 400 (1999))