Testosterone, territorial response, and song in seasonally breeding tropical and temperate Stonechats

Apfelbeck, B., Mortega, K. G., Flinks, H., Illera, J. C. and Helm, B. (2017) Testosterone, territorial response, and song in seasonally breeding tropical and temperate Stonechats. BMC Evolutionary Biology, 17(1), 101. (doi: 10.1186/s12862-017-0944-9) (PMID:28412929) (PMCID:PMC5392926)

Abstract

Background: Testosterone facilitates physiological, morphological, and behavioral changes required for breeding in male vertebrates. However, testosterone concentrations and the link between its seasonal changes and those in reproductive behaviors vary greatly among species. To better understand the impact of tropical and temperate environments and life history factors on this variation, we have compared testosterone, territorial behavior and song performance across sequential stages of the breeding season in males of 16 closely related taxa of East African tropical and West European temperate stonechats (Saxicola spp), which all breed during a short breeding season, but differ in migratory behavior, seasonal territory-acquisition and pace of life. Results: We found that generally, the profiles of testosterone and territorial behavior were similar across latitudes. African stonechats with a slow pace of life had equally high peak testosterone concentrations and responded as aggressively to an intruder as European stonechats with a fast pace of life. However, song performance at the beginning of the breeding season was lower in African than in European stonechats. The differences in song performance were not associated with variation in testosterone levels between tropical and temperate stonechats. Conclusions: The results suggest a very similar role for testosterone as a mediator of high intensity territorial aggression during the fertile period of females in tropical and temperate stonechats, which all are highly seasonal, locally synchronous breeders. A potential explanation may be high risk of extra-pair copulations which has been associated with synchronous breeding. Interestingly, an association was not consistent for song performance. Our data suggest that song performance can be disassociated from peak testosterone levels depending on its role in breeding behavior. Despite similar testosterone levels, European males, which early in the breeding season acquire territories and mates, showed greater song performance than African stonechats, which maintain year-round territories and pair-bonds. Taken together, our study comparing related taxa of old world songbirds suggests that short breeding seasons may be a major selective force for high peak testosterone levels during breeding regardless of latitude and pace of life, but that particular behaviors, in our case song, can be uncoupled from peak testosterone levels.

• Item Type: Articles
• Additional Information: This work was supported by the Alexander von Humboldt Foundation (BA), the German Science foundation (DFG, research grant to BH grant HE3488/5–1) and the Max Planck Institute for Ornithology (testosterone assays). This work was supported by the German Research Foundation (DFG) and the Technical University of Munich (TUM) in the framework of the Open Access Publishing Program.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Mortega, Miss Kim Geraldine and Apfelbeck, Dr Beate Anna and Helm, Dr Barbara
• Authors: Apfelbeck, B., Mortega, K. G., Flinks, H., Illera, J. C., and Helm, B.
• College/School: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: BMC Evolutionary Biology
• Publisher: BioMed Central
• ISSN: 1471-2148
• ISSN (Online): 1471-2148
• Copyright Holders: Copyright © 2017 The Authors
• First Published: First published in BMC Evolutionary Biology 17(1):101
• Publisher Policy: Reproduced under a Creative Commons License