Cooperation and Conflict in the Evolution of Signal Interactions

Various inv ertebrate and vertebrate species in which males produce acoustic or biolumi nescent signals for long-range sexual advertisement exhibit collec­ tive patterns of temporal signal interactions. These patterns range fro m simple concentrations of signaling during a narrow diel interval to synchronous and alternating interactions entailing precisely timed phase relationships between neighboring individuals. Signals invo lved in synchrony and alternation are generally produced with rhythms that are under the control of central nervous oscilla tors. Neighboring individuals effe ct these interactions via mutual phase delays or phase advances of their oscill ators or actual changes in the fre e-run­ ning periods of their oscilla tors. Both synchrony and alternation may repr esent adaptations to avoid spiteful behavior or to maximize the ability of a local group to attract females or evade natural enemies. Alternatively, these collec­ tive patterns may represent incid ental outcomes of competition between males jamming each othe r' s signals. The neural mechanisms that effect signal jam­ ming can be selected for by critical psychophysical factors such as precedence eff ects. Additional competitive pressures that may generate synchrony, alter­ nation, and other collective patterns of signal interaction include mutual as­ sessment of rivals, evasion of detection by dominant individ uals, disruption of communication within courting pairs, and narr owness of the time intervals during which recep tive females are present.