Condition dependence of advertisement calls in male African clawed frogs
Variations in the costs or benefits of signaling may result in variations in signaling strategies. The adverse conditions hypothesis suggests that reliable signaling can be improved under stress or adverse environmental conditions, but the empirical cases are limited. In the present study, we manipulated food availability in male Xenopus laevis in order to determine whether certain characteristics of advertisement call in X. laevis are condition-dependent and how food depletion modulates the association between individual condition and signaling performance. The results showed that although frogs tend to decrease their within-bout call rate compared to other call characteristics (calling effort and dominant frequency) under food constraint, none of them was statistically significantly affected by food restriction. However, within-bout call rate was positively coupled with adaptive immunocompetence in starved frogs, and the correlation was decoupled in those with free access to food. These results support that within-bout call rate is a condition-dependent characteristic of advertisement call and even mild adverse conditions may enhance reliable signaling in X. laevis, probably due to enlarging the relative fitness difference between high- and low-condition individuals.
KeywordsCondition dependence Body condition Immunocompetence Sexual selection African clawed frogs Xenopus laevis
We thank all the members of the Behavioral Neuroscience Group for their discussion and help with this study. We are grateful to Steven E. Brauth, The University of Maryland, for improving the English text. The study was conceived and designed by JFC and XCW. Experiments were performed by XCW, JFC, ZZJ and YC; results were analyzed and interpreted by JFC and XCW. The paper was written by JFC and XCW. This work was financially supported by grants from the National Natural Science Foundation of China (31370431) to JFC, (31270458) to ZZJ, and (31270042) to JGC.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Human and animal rights statement
This article does not contain any studies with human participants performed by any of the authors. All animal procedures in this study were carried out in accordance with and approved by the Animal Care and Use Committee at the Chengdu Institute of Biology, Chinese Academy of Sciences. All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.
- Andersson MB (1994) Sexual selection. Princeton University Press, PrincetonGoogle Scholar