Colour morph predicts social behaviour and contest outcomes in a polymorphic lizard (Podarciserhardii)

Abstract

Space is a limited resource in which many animals need to perform basic functions such as feeding and reproducing. Competition over access to space can induce a variety of behaviours that may result in differential access to crucial resources related to survival and fitness. The Aegean wall lizard, Podarcis erhardii , is a colour-polymorphic lizard that inhabits dry stone walls where they access food, safely thermoregulate, shelter from predators and interact with other lizards. Many colour-polymorphic species have morphs with distinct behavioural strategies, which may play a role in morph evolution and maintenance. Here, we conducted the first behavioural experiments on P. erhardii colour morphs. Our goal was to compare morph competitive ability and characterize morph differences in social behaviours using laboratory contest experiments over limited heated space on a stone wall in a neutral arena. Contest experiments revealed that colour morph, not size, predicted intermorph contest outcomes. White and yellow morphs were associated with winning and the orange morph was associated with losing contests. Male colour morphs exhibited different levels of aggressive, boldness, chemical signalling and visual signalling behaviours depending on which morph they were in contest with. White morphs always performed aggressive and scent-marking behaviours more frequently during contests with other morphs. Yellow morphs performed aggressive, bold, chemical signalling and visual signalling behaviours at intermediate frequencies relative to other morphs. Orange morphs performed aggressive behaviours equally often when in contest with yellow morphs but performed all other behaviours less frequently against yellow and white morphs. Considering these results, behavioural variation among P. erhardii colour morphs may promote morph maintenance. • Male lizard colour morphs differed in their ability to win staged contests for space. • White and yellow morphs were associated with winning contests over space. • Larger orange morphs were associated with losing and were the least aggressive. • White morphs were the most aggressive and scent-marked territories often. • Different social strategies among morphs may help maintain polymorphism.