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 phylogenet ic trees based on morphological and biochemical data. It was found tha t the characters that make up a call evolve at different rates. In hyl ids, characters allied with the morphological aspects of sound product ion were more conservative than those based on the physiological or be havioural aspects of calling, while in bufonids divergence rates of th ese character types did not differ. Observed patterns of character cha nge within sets of close relatives suggest a focus for process-oriente d research by identifying the origin and direction of important change s in calling behaviour.