Why does the complexity of functionally equivalent signals vary across closely related species?

Animal signals are observed to vary widely in complexity among species, but why this should be the case—especially among closely related taxa—is unclear. Identifying the selective forces that drive these differences is important for understanding signal evolution, as well as the origins of communication more generally. We used a measure derived from information theory to quantify the complexity of visual territorial advertisement displays performed by males of closely related taxa of Puerto Rican Anolis lizard. In general, the information potential of visual displays appeared to be high compared to signals of other taxonomic groups (e.g., other lizards, birds). Nevertheless, there was still considerable variation in signal complexity among the Anolis taxa studied. We found a strong relationship between signal complexity and phylogeny for some aspects of the advertisement display traditionally thought to be important in species recognition. Other aspects of the display tended to vary ind..., Details are provided in full in the published paper associated with this data set, Please see the associated read me file for this data set for full description of data provided