Male genital titillators and the intensity of post-copulatory sexual selection across bushcrickets

Lehmann, Gerlind U.C; Gilbert, James DJ; Vahed, Karim; Lehmann, Arne W

Abstract

Animal genitalia are diverse and a growing body of evidence suggests that they evolve rapidly under post-copulatory sexual selection. This process is predicted to be more intense in polyandrous species, although there have been very few comparative studies of the relationship between the complexity of genital structures in males and measures of the degree of polyandry. In some bushcricket families, males possess sclerotised copulatory structures known as titillators, which are inserted into the female’s genital chamber and moved rhythmically. Like other genital structures, bushcricket titillators are widely used as important taxonomic characters and show considerable variation across species in structure, shape and the extent to which they are spined. Here, we examine relationships between the presence/absence of titillators, titillator complexity and both mating frequency and the degree of polyandry in bushcrickets, using phylogenetic comparative analyses. Using published sources combined with original observations, data were obtained for the mean level of polyandry, the duration of the male and female sexual refractory periods and the level of complexity of titillators. To analyse data, we fitted phylogenetic generalised least squares models. No significant relationships were found between titillator presence or complexity and either the level of polyandry, duration of the male’s sexual refractory period or the ratio of the female and male sexual refractory periods. The duration of the female’s refractory period, however, was positively associated with titillator presence and negatively associated with titillator complexity. The data therefore partially support the hypothesis that post-copulatory sexual selection drives genital evolution in this taxon.

Citation

Lehmann, G. U., Gilbert, J. D., Vahed, K., & Lehmann, A. W. (2017). Male genital titillators and the intensity of post-copulatory sexual selection across bushcrickets. Behavioral ecology, 28(5), 1198-1205. https://doi.org/10.1093/beheco/arx094

• Journal Article Type: Article
• Acceptance Date: Jun 21, 2017
• Online Publication Date: Jul 10, 2017
• Publication Date: 2017-09
• Deposit Date: Oct 24, 2017
• Publicly Available Date: Jul 13, 2018
• Journal: Behavioral ecology
• Print ISSN: 1045-2249
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 28
• Issue: 5
• Pages: 1198-1205
• DOI: https://doi.org/10.1093/beheco/arx094
• Keywords: Sexual selection; Polyandry; Refractory period; Genitalia; Orthoptera
• Public URL: https://hull-repository.worktribe.com/output/455943
• Publisher URL: https://academic.oup.com/beheco/article/doi/10.1093/beheco/arx094/3946647/Male-genital-titillators-and-the-intensity-of-post
• Additional Information: This is the accepted manuscript of an article published in Behavioral ecology, 2017. The version of record is available at the DOI link in this record.
• Contract Date: Oct 24, 2017