Variation in signal timing behavior: implications for male attractiveness and sexual selection

Mate choice often takes place in group settings, such as leks or choruses, in which numerous individuals display and compete for mates simultaneously. In addition to well-known preferences for male traits like size and signaling rate, females of group-displaying species often show preferences that are based on the relative timing of male signals, generally preferring the leading signal. Variation in male signal timing behavior may therefore affect male attractiveness and, ultimately, reproductive success. I used acoustic communication in green treefrogs (Hyla cinerea) to assess the amount of signal timing variation found in natural choruses and to test hypotheses about the sources of variation in signal timing behavior. I recorded dyads of vocally interacting males in the field to describe patterns of variation in signal timing behavior. Incorporating information about female signal timing preferences, I also assessed the amount of variation in signal timing that is likely to be selectively neutral, as well as the amount that is likely under selection by female choice because it involves attractive or unattractive signal placement. I show that there is considerable variation in signal timing behavior, particularly involving neutral signal timing placement. I also show that between-male variation in other traits (size, signal period) is partly linked to variation in signal timing behavior and discuss these findings in terms of male attractiveness and sexual selection in group-displaying organisms.