Bigger Is Not Always Better: Females Prefer Males of Mean Body Size in Philautus odontotarsus

PLoS One. 2016 Feb 22;11(2):e0149879. doi: 10.1371/journal.pone.0149879. eCollection 2016.

Abstract

Most species are believed to evolve larger body sizes over evolutionary time. Previous studies have suggested that sexual selection, through male-male competition and female choice, favors larger males. However, there is little evidence of selection against large size. The female serrate-legged small treefrogs (Philautus odontotarsus) must carry passive males from leks to breeding grounds over relatively long distances after amplexus to find a suitable place to lay eggs. The costs of large male size may therefore decrease mating success due to reduced agility and/or higher energy requirements. Thus, we hypothesized that selection would not favor larger males in P. odontotarsus. Females can assess male body size on the basis of the dominant frequency of male calls in frogs. To assess female P. odontotarsus preferences for a potential mate's body size, male calls of high, average and low dominant frequency were played back to the females in phonotaxis experiments. Results showed that most females prefer the advertisement call with average dominant frequency. In addition, we compared the body mass distribution of amplectant males with that of single males in nature. The body masses of amplectant males are more narrowly distributed in the intermediate range than that of single males. The phonotaxis results and the data of actual female preferences in the field show that females strongly prefer potential mates of mean body sizes, consistent with the view that, in this species at least, larger males are not always perceived as better by females. In the present study, P. odontotarsus provides an example of an amphibian species in which large size does not have an advantage in mating success for males. Instead, our results provide evidences that stabilizing selection favors the optimal intermediate size of males.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anura / physiology
  • Body Size*
  • Female
  • Male
  • Sexual Behavior, Animal / physiology*

Grants and funding

This work was supported by the National Natural Science Foundation of China grant 31270042 (JC), 31260518 (JW), 31372217 (GF), Youth Professor Project of CIB (JC), the Project of Comprehensive Strategic Cooperation between Guangdong Province and Chinese Academy of Sciences grant 2012B091100260 (JC), Youth Innovation Promotion Association of CAS and Open Fund of the Hainan Province Key Laboratory of Tropical Plant and Animal Ecology (Hainan Normal University) (JC). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.