Sperm competition shapes gene expression and sequence evolution in the ocellated wrasse
Wright, A. E.
Marsh-Rollo, S. E.
Nugent, B. M.
Alonzo, S. H.
Mank, J. E.
- Publisher: Blackwell Publishing
Masculinization, alternative reproductive tactics, morphs, positive selection, expression variance, sex-biased gen
Gene expression differences between males and females often underlie sexually dimorphic phenotypes and the expression levels of genes that are differentially expressed between the sexes is thought to respond to sexual selection. Most studies on the transcriptomic response to sexual selection treat sexual selection as a single force, but post-mating sexual selection in particular is expected to specifically target gonadal tissue. The three male morphs of the ocellated wrasse (Symphodus ocellatus) make it possible to test the role of post-mating sexual selection in shaping the gonadal transcriptome. Nesting males hold territories and have the highest reproductive success, yet we detected feminisation of their gonadal gene expression compared to satellite males. Satellite males are less brightly coloured and experience more intense sperm competition than nesting males. In line with post-mating sexual selection affecting gonadal gene expression, we detected a more masculinised expression profile in satellites. Sneakers are the lowest quality males and showed both de-masculinisation and de-feminisation of gene expression. We also detected higher rates of gene sequence evolution of male-biased genes compared to unbiased genes, which could at least in part be explained by positive selection. Together, these results reveal the potential for post-mating sexual selection to drive higher rates of gene sequence evolution and shape the gonadal transcriptome profile.