SELECTIVE RESPONSIVENESS TO LONG-RANGE ACOUSTIC-SIGNALS IN INSECTS AND ANURANS

Insects and anurans show various patterns of selective responsiveness to playbacks of natural and synthetic sounds. Preferences and tuning o f the auditory system most often match one or more strongly emphasized frequency components in long-range, mate-attracting signals typical o f conspecific individuals, but exceptions, in which frequencies lower or higher than the mean are preferred, occur in some species. In some insects the most preferred frequencies may correspond to regions that maximize localizability of signals rather than regions of maximum sens itivity. Patterns of preference for fine-temporal properties are typic ally stabilizing within a population; females prefer values near the m ean and few males produce calls with values that deviate sufficiently to make them less attractive than calls with average values. Preferenc es for gross temporal properties (e.g., the rate and duration of signa ling) are usually highly directional, with much higher than mean value s preferred. In anurans, call rate is a better predictor of male matin g success than dominant frequency. Nevertheless, a variety of factors, especially close-range assessments that are common in insects, may mo dify or negate the advantages of producing long-range signals of high relative attractiveness. The evolutionary consequences of selective re sponsiveness in anurans and insects are discussed.