Male Male Combats in a Polymorphic Lizard: Residency and Size, but not Color, Affect Fighting Rules and Contest Outcome

摘要

Theoretical models predict that the outcome of dyadic agonistic encounters between males is influenced by resource-holding potential,resource value, and intrinsic aggressiveness of contestants. Moreover, in territorial disputes residents enjoy a further obviouscompetitive advantage from the residency itself, owing to the intimate familiarity with their territory. Costs of physical combats are,however, dramatically high in many instances. Thus, signals reliably reflecting fighting ability of the opponents could easily evolve inorder to reduce these costs. For example, variation in color morph in polymorphic species has been associated with dominance inseveral case studies. In this study, we staged asymmetric resident-intruder encounters in males of the common wall lizard Podarcismuralis, a species showing three discrete morphs (white, yellow, and red) to investigate the effects of asymmetries in color morph,residency, and size between contestants on the outcome of territorial contests. We collected aggression data by presenting eachresident male with three intruders of different color morph, in three consecutive tests conducted in different days, and videotaping theirinteractions. The results showed that simple rules such as residency and body size differences could determine the outcome of agonisticinteractions: residents were more aggressive than intruders, and larger males were competitively superior to smaller males. However,we did not find any effect of color on male aggression or fighting success, suggesting that color polymorphism in this species is not asignal of status or fighting ability in intermale conflicts. Aggr. Beh