COOPERATION AND CONFLICT IN THE EVOLUTION OF SIGNAL INTERACTIONS

Various invertebrate and vertebrate species in which males produce acoustic or bioluminescent signals for long-range sexual advertisement exhibit collective patterns of temporal signal interactions. These patterns range from simple concentrations of signaling during a narrow diel interval to synchronous and alternating interactions entailing precisely timed phase relationships between neighboring individuals. Signals involved in synchrony and alternation are generally produced with rhythms that ace under the control of central nervous oscillators. Neighboring individuals effect these interactions via mutual phase delays or phase advances of their oscillators or actual changes in the free-running periods of their oscillators. Both synchrony and alternation may represent adaptations to avoid spiteful behavior or to maximize the ability of a local group to attract females or evade natural enemies. Alternatively, these collective patterns may represent incidental outcomes of competition between males jamming each other's signals. The neural mechanisms that effect signal jamming can be selected for by critical psychophysical factors such as precedence effects. Additional competitive pressures that may generate synchrony, alternation, and other collective patterns of signal interaction include mutual assessment of rivals, evasion of detection by dominant individuals, disruption of communication within courting pairs, and narrowness of the time intervals during which receptive females are present.