Form emergence and fixation of head bobbing displays in the green anole lizard (Anolis carolinensis): a reptilian model of signal ontogeny.

Signal ontogeny was examined in green anoles (Anolis carolinensis). From 1,246 head bob displays given by 114 juveniles, it was found that juveniles possessed all 3 display types (A, B, and C) described for adults and that C displays were present at hatching, but A and B displays appeared to emerge gradually from a common precursor. Durations of the head bobs and pauses that make up juvenile displays tended to be more variable (i.e., less stereotyped) than those of adult displays. However, within the juvenile class, sex, age (or size), social context, and rearing environment (field or lab) had no effect on display structure or stereotypy. Thus, in contrast to typical signal ontogeny in songbirds and mammals, components of the green anole signal repertoire are expressed from early development. Similar to signal ontogeny in altricial species, maturation is nevertheless important for the complete and stereotyped expression of the adult signal repertoire.