Influence of conspecific and heterospecific cues on phonotaxis behavior in a polyandrous treefrog
Although a large proportion of the literature has addressed the direction and preference of female choice in frogs, research about how males locate a breeding site and what strategies are involved in aggregation has been much less explored. By using broadcasting tests on a polyandrous choral treefrog Rhacophorus prasinatus, we examined how male frogs use conspecific and heterospecific signals to locate a chorus by asking the following questions: (1) Do male frogs prefer to join a large or a small chorus? (2) Do male frogs prefer to approach a high-quality or a low-quality male? (3) Do males utilize heterospecific calls to locate the potential breeding sites? (4) Do male frogs orient toward or avoid choruses containing heterospecific calls? Our results indicated that males prefer to join a large rather than small chorus. Low-quality males tend to approach high-quality males, which might be explained as the sneaking behavior of satellite males. Furthermore, males may use heterospecific calls delivered by a noncompetitive sympatric species (a ranid frog) to find potential breeding sites, but not by a sympatric competitor (another rhacophorid frog) that occupies a similar niche. Although the males did not show significant preference between conspecific chorus and mixed-specific chorus in the broadcasting tests, recapture records in the wild indicated that a high ratio of males would leave the mixed-specific choruses and move toward conspecific choruses in the next capture event.
Although a large proportion of the literature has addressed the direction and preference of female choice in frogs, research about how males locate a breeding site and what strategies are involved in aggregation has been much less explored. Our study represents one of the first to test the orientation of males during breeding season, when the spatial scale in the experimental design is comparable to the real situation in the wild. Our results supported the prediction that both conspecific and heterospecific cues are used as information for males to assess the quality of breeding sites. Heterospecific calls may play dual functions for the males, which might become interference when coexisting with conspecific calls but may also provide cues for a potential habitat when conspecific calls are absent.
KeywordsChorus attraction hypothesis Heterospecific attraction hypothesis Polyandry Resource partition Satellite males Self-evaluation Sneakers
We appreciate the Department of Forestry and Nature Conservation, Private Chinese Culture University, which provided us the wonderful experimental site for this research. Dr. Yi-Chung Wang and Mr. Jyh-Chin Lin from this department provided us extra helps during the conduction of the experiments. We also appreciate Dr. Yi-Huey Chen, Dr. Pei-Jen Lee Shaner, and Dr. Yu-Ying Hsu for their advice in the experimental design and statistics. Finally, we appreciate the anonymous reviewers for providing precious comments which greatly improved the quality of this paper.
This work was supported by the Ministry of Science and Technology, Taiwan (MOST 105-2621-B-003-001-MY3).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All the treatment procedures in this study followed the animal use protocols approved by Institutional Animal Care and Use Committee (IACUC), National Taiwan Normal University (license no. 107023), and Chinese Culture University (CCU-IACUC-104008). All these protocols were further reviewed and certificated by the Forest Bureau, Council of Agriculture, Taiwan (license no. 1041701403-105-002; no. 1061700773-106-026) and were performed in accordance with the local law of the Wildlife Conservation Act in Taiwan.
- Beckers OM, Schul J (2004) Phonotaxis in Hyla versicolor (Anura, Hylidae): the effect of absolute call amplitude. J Comp Physiol A 190:869–876Google Scholar
- Chen S-L (1992) The reproductive behavior and ecology of emerald green tree frog (Rhacophorus smaragdinus). MSc thesis, National Taiwan Normal UniversityGoogle Scholar
- Chen T-Y (2002) Male advertisement call and female choice in Moltrecht’s treefrog, Rhacophorus moltrechti, from Taiwan. MSc thesis, National Cheng Kung UniversityGoogle Scholar
- Gerhardt HC, Huber F (2002) Acoustic communication in insects and anurans: common problems and diverse solutions. University of Chicago Press, ChicagoGoogle Scholar
- Lu Y-T, Chen S-H (2012) Study on resource partitioning of 6 frogs community in a still waterpond located in the Tatung Shan of New Taipei City. MSc thesis, National Taipei University of EducationGoogle Scholar
- Mou Y, Risch J, Lue K (1983) Rhacophorus prasinatus, a new tree frog from Taiwan, China (Amphibia, Anura, Rhacophoridae). Alytes 2:154–162Google Scholar
- Rehberg-Besler N, Doucet SM, Mennill DJ (2016) Overlapping vocalizations produce far-reaching choruses: a test of the signal enhancement hypothesis. Behav Ecol 28:494–499Google Scholar
- Wells KD (2001) The energetics of calling in frogs. In: Ryan MJ (ed) Anuran communication. Smithsonian Institution Press, Washington, DC, pp 45–60Google Scholar