Intrasexual selection drives sensitivity to pitch, formants and duration in the competitive calls of fallow bucks

Benjamin J. Pitcher*, Elodie F. Briefer, Alan G. McElligott

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)
8 Downloads (Pure)

Abstract

Background: Mammal vocal parameters such as fundamental frequency (or pitch; fo ) and formant dispersion often provide information about quality traits of the producer (e.g. dominance and body size), suggesting that they are sexually selected. However, little experimental evidence exists demonstrating the importance of these cues in intrasexual competition, particularly fo. Male Fallow deer (bucks) produce an extremely low pitched groan. Bucks have a descended larynx and generate fo well below what is expected for animals of their size. Groan parameters are linked to caller dominance, body size and condition, suggesting that groans are the product of sexual selection. Using a playback experiment, we presented bucks with groans that had been manipulated to alter vocal cues to these male characteristics and compared the response to the same, non-modified (natural) groans. Results: We experimentally examined the ability of bucks to utilise putative cues to dominance (fo ), body size (formant frequencies) and condition (groan duration), when assessing competitors. We found that bucks treated groans with lowered fo (more dominant), and lowered formant frequencies (larger caller) as more threatening. By contrast, groans with raised formant frequencies (smaller caller), and shorter durations (more fatigued caller) were treated as less threatening. Conclusions: Our results indicate that intrasexual selection is driving groans to concurrently convey caller dominance, body size and condition. They represent the first experimental demonstration of the importance of fo in male competition in non-human mammals, and show that bucks have advanced perception abilities that allow them to extract information based on relatively small changes in key parameters.

Original languageEnglish
Article number149
Pages (from-to)1-13
Number of pages13
JournalBMC Evolutionary Biology
Volume15
DOIs
Publication statusPublished - 17 Aug 2015

Bibliographical note

Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • Body size
  • Condition
  • Dominance
  • Fundamental frequency
  • Male-male competition
  • Sexual selection
  • Signalling
  • Vocal

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