PATTERNS OF ADVERTISEMENT CALL EVOLUTION IN TOADS AND CHORUS FROGS

Patterns of evolution in the acoustic signals of two groups of anuran amphibians were examined. Call character matrices for clades of Bufo (Bufonidae) and Pseudacris (Hylidae) were derived from analysis of tape-recorded calls, and these call characters were mapped onto phylogenetic trees based on morphological and biochemical data. It was found that the characters that make up a call evolve at different rates. In hylids, characters allied with the morphological aspects of sound production were more conservative than those based on the physiological or behavioural aspects of calling, while in bufonids divergence rates of these character types did not differ. Observed patterns of character change within sets of close relatives suggest a focus for process-oriented research by identifying the origin and direction of important changes in calling behaviour.