Meeting Abstract

86.4  Sunday, Jan. 6  Constraints on song complexity generalize across multiple songbirds TAFT, BN; Univ. of Wisconsin, Parkside truthauction@gmail.com

Complex signals may evolve in response to different selection intensities, either continuously increasing in elaboration or reaching a steady state that is maintained by constraints. Detailed quantitative measures of signal complexity can help identify these different patterns of signal evolution and elucidate the mechanisms that produce them. Here I demonstrate a general method for quantifying the complexity of signal elements, derived from a new automated method for describing sounds as landmarks. I found that the acoustically dissimilar songs of four passerine species seem to have similar constraints between song element complexity and the rate of element production. Individuals from species with complex song elements sing at a slower rate than those from species with simple elements. Two of the species also show the same pattern of constraints among individuals. Element complexity also increases during the vocal learning process of a third species. The tradeoff between complexity and element rate is consistent with a hypothesis of production tradeoffs, does not appear to correspond to overall strength of sexual selection, and may also be explained by selection for effective communication in the face of tradeoffs in auditory perception or processing.