Behavioural display systems across nine Anolis lizard species: sexual dimorphisms in structure and function

Relationships between structure and function are a primary focus in biology, yet they are most often considered within individual species. Sexually dimorphic communication behaviours and the morphology of associated structures can vary widely, even among closely related species, and these traits provide an ideal opportunity to investigate the evolution of structure-function patterns. Using nine Anolis lizard species, we addressed a series of questions regarding sex differences in and the evolution of relationships between extension of the throat fan (dewlap) and morphology of the muscles and cartilage controlling it. The main results indicated that within species, males displayed the dewlap more often than females and consistently exhibited larger associated structures. These data are consistent with work in other vertebrates in which corresponding sex differences in reproductive morphology and behaviour have been documented. Across species, however, we found no evidence that the rate of dewlap extension evolved in association with dewlap morphology. Thus, we provide an example of traits that, when considered in a phylogenetic framework, exhibited limited associations between behaviour and morphology, perhaps as the result of constraints imposed by the ecological contexts in which different species occur.