Correlated evolution between male ejacualte allocation and female remating behaviour in seed beetles (Bruchidae)
2008 (English)In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 21, no 2, 471-479 p.Article in journal (Refereed) Published
The pattern with which males allocate their ejaculate resources is at the heart of postmating sexual selection, and theory suggests that female remating rate is key in determining the selective regime under which male ejaculate traits evolve. Intraspecific studies have shown that males are able to adaptively allocate ejaculates according to the intensity of sperm competition, but observational data does not allow explicitly comparative tests of theory in this field. Using a group of seed beetles as a model system, we analyzed experimental quantifications of a suite of relevant male and female traits and behaviors in a phylogenetic comparative framework. We found a strongly and positively correlated evolution between the weight of males’ first ejaculate and the rate at which ejaculate weight decreases over successive matings. Sperm competition theory predicts that increased female remating should result in the evolution of larger male testes but smaller ejaculates, and both of these predictions were upheld in seed beetles. Theory also predicts that increased female remating should lead to the evolution of more prudent allocation of ejaculate resources over successive matings. In contrast to this prediction, we found that elevated female remating was associated with a less prudent ejaculate allocation. We suggest that this pattern of correlated evolution, apparently incongruent with classic sperm competition theory, is the result either of trade-offs between ejaculate expenditure and other competing demands or of evolution in total resource acquisition rather than in the evolution of resource allocation.
Place, publisher, year, edition, pages
2008. Vol. 21, no 2, 471-479 p.
acessory gland products, Callosobruchus, coevolution, mating system, nuptial gift, polyandry, sexual selection, sperm allocation, sperm competition, Zabrotes
IdentifiersURN: urn:nbn:se:su:diva-61565DOI: 10.1111/j.1420-9101.2007.01494.xOAI: oai:DiVA.org:su-61565DiVA: diva2:436330