Species Recognition in Anolis grahami (Sauria, Iguanidae): Evidence from Responses to Video Playbacks of Conspecific and Heterospecific Displays

The visual displays of male anoles (Anolis sp.) are usually viewed as characters that facilitate species recognition. This presumption stems largely from the extensive variation in the head bobbing movements and dewlap colouration in males of this genus. However, few experimental data exist that illuminate the importance of these visual signals for species recognition. We presented adult male Anolis grahami with colour-videotaped sequences of displays from conspecifics and from three heterospecific species of anoles. The congenerics (A. carolinensis, A. conspersus, and A. sagrei) were chosen on the basis of their phylogenetic and geographical relationships with A. grahami. Stimulus males were filmed at a constant distance and orientation from the video camera, and edited sequences of their displays were presented at a standard distance from subjects. Video playbacks allowed us to equalize the quantity of display performed by each stimulus species, and to eliminate stimulus/subject interactions as well as inter-trial variation in stimulus behaviour. Results revealed that the subjects responded more strongly to conspecific than to heterospecific displays on all behavioural variables examined, but there was no indication of discrimination among the displays of the three congeneric species.