Male Contest Competition And The Coevolution Of Weaponry And Testes In Pinnipeds
2012 (English)In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 66, no 11, 3595-3604 p.Article in journal (Refereed) Published
Male reproductive success is influenced by competitive interactions during precopulatory and postcopulatory selective episodes. Consequently, males can gain reproductive advantages during precopulatory contest competition by investing in weaponry and during postcopulatory sperm competition by investing in ejaculates. However, recent theory predicts male expenditure on weaponry and ejaculates should be subject to a trade-off, and should vary under increasing risk and intensity of sperm competition. Here, we provide the first comparative analysis of the prediction that expenditure on weaponry should be negatively associated with expenditure on testes mass. Specifically, we assess how sexual selection influences the evolution of primary and secondary sexual traits among pinnipeds (seals, sea lions, and walruses). Using recently developed comparative methods, we demonstrate that sexual selection promotes rapid divergence in body mass, sexual size dimorphism (SSD), and genital morphology. We then show that genital length appears to be positively associated with the strength of postcopulatory sexual selection. However, subsequent analyses reveal that both genital length and testes mass are negatively associated with investment in precopulatory weaponry. Thus, our results are congruent with recent theoretical predictions of contest-based sperm competition models. We discuss the possible role of trade-offs and allometry in influencing patterns of reproductive trait evolution in pinnipeds.
Place, publisher, year, edition, pages
2012. Vol. 66, no 11, 3595-3604 p.
Contest competition, Ejaculate allocation, Genital evolution, Sexual selection
IdentifiersURN: urn:nbn:se:su:diva-116462DOI: 10.1111/j.1558-5646.2012.01713.xISI: 000310477600023OAI: oai:DiVA.org:su-116462DiVA: diva2:806593