No 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, we ask how female Eastern Gray Treefrogs (Hyla versicolor) respond to isolated and 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 study provides novel insight into the mate choice heuristics involved in animal choruses.

No abstract

Size‐assortative mating in frogs and toads should increase fitness, because pairs consisting of partners well matched for size should also have a higher proportion of fertilized eggs. We examined whether the size ratios of mated males and females had an effect on fertilization success in Eastern Gray Treefrogs and tested whether the naturally observed size ratios could be attributed to female preferences or stochastic effects (male availability). We show that in this species, mating with a roughly size‐matched partner (m/f size ratios between 0.9 and 1.1) provides direct benefits by increasing fertilization success. Although the frequency of male advertisement calls would provide females with a cue by which to estimate the body size of a potential partner, the female call frequency preferences are not size‐dependent. Call frequency preferences are therefore unlikely to result in the choice of a well‐matched partner. The size distributions of males and females available at the breeding site appear to result in the distribution of male/female size ratios and the weak pattern of size‐assortative mating we observed in nature, despite apparently random mating with respect to body size.