Woe is the loner: Female treefrogs prefer clusters of displaying males over single "hotshot" males.

Abstract

Communal displays such as leks and choruses are puzzling phenomena, as it is not obvious why signalers or choosers should aggregate. It has been hypothesized that signalers in leks enjoy higher per-capita reproductive success because choosers prefer to sample among dense configurations ("clusters") that are easier to compare.Although female preferences as well as the signal features of attractive males are well characterized in many chorusing species, we know little about how mate sampling is influenced by the spatial dynamics within communal displays. Here, weask how female Eastern Gray Treefrogs (Hyla versicolor) respond toisolatedand clustered call stimuli in a simple one versus three playback design.We explored (i) whether females exhibit a general preference for call clusters, (ii) whether spatial preference is robust to call-feature preference, and (iii) how this affects the relative success of attractive and unattractive males in different spatial combinations. We found generalized spatial discrimination against lone callers but did observe fine-scale assessment of call features within clusters. The prominence of the spatial preference impacts the attractiveness of males, conferring particular advantage to attractive callers within clusters, while reducing attractiveness of isolated males regardless of their acoustic features. Our findings indicate that female frogs navigate complex choruses by initially orientating toward clusters of calling males, and then assess call features within them. This studyprovides novel insightinto the mate choice heuristics involved in animal choruses.