Population variation in signaling behavior and contest outcome in the jacky dragon

Being aggressive and by extension, dominant, is an important mechanism for determining access to resources such as mates or territories. While predictors of contest outcome and dominance are increasingly studied, we have a poor understanding of how they vary across populations. Here, I use the widely distributed Australian agamid lizard, the Jacky dragon (Amphibolurus muricatus), to quantify variation in features predicting contest outcome among males of different populations. I measured physical attributes, maximal physiological performance capacity (sprint speed, endurance, bite force) and visual displays during staged encounters. I found that morphology, performance capacity and the type and frequency of visual displays used during agonistic interactions varied significantly across populations. Contest winners from the Cann River State Forest population favored tail-flicks and push-up/body-rocks, while those from Royal National Park were more likely to chase and individuals from Yarratt State Forest performed more bite-lunges than other populations. The losers of contests also differed in their displays. Individuals from the Cann River population were dominant over the others based on behavioral attributes (i.e., aggressive visual displays, chases and bite-lunges). I suggest that population differences in signal form and function could have implications for range dynamics as populations come into contact in an era of rapid environmental change.