Males often fight over resources, but to avoid costly fights they display to each other instead to size each other up. If they decide it's not worth fighting an opponent, they back out. Interested to know which features of a signal male Jacky dragon lizards rely on to assess their opponents, Daniel Van Dyk, Alan Taylor and Chris Evans from Macquarie University, Australia, filmed male Jacky dragon displays (). The lizards' displays involve rapid arm waves followed by sequences of push-ups and body rocks, along with tail flicking and expansion of their gular pouches in the throat. The team used a film editing program to make up sequences of Jacky dragon displays, each containing the same number of push-up/body rocks, but with groups of push-up/body-rocks divided into bouts,separated by different time intervals. Playing these sequences to test lizards to see how they responded, they found that the test lizards were less aggressive towards their virtual opponent when the displays were arranged into fewer bouts, that is, when push-up/body-rocks were more concentrated. This suggests that lizards rapidly assess their opponent's prowess by averaging the number of push-up/body-rocks they complete per bout, and the results will help researchers work out the rules that govern aggressive interactions between animals.
Van Dyk, D. A., Taylor, A. J. and Evans, C. S.(
2007
). Assessment of repeated displays: a test of possible mechanisms. J. Exp. Biol.
210
,3027
-3035.
