Sperm competition shapes gene expression and sequence evolution in the ocellated wrasse

Abstract

21Gene expression differences between males and females often underlie sexually dimorphic

Genomic analysis of Sparus aurata reveals the evolutionary dynamics of sex-biased genes in a sequential hermaphrodite fish

“…aculeatus . At variance with what has been reported in nearly all species investigated so far, including teleost fish 6,7 , in S . aurata female- and male-biased genes had similar evolutionary rates to UB genes (Fig.…”

“…In nearly all cases, male-biased genes show higher rates of protein-coding sequence evolution, although exceptions have been reported 4,5 . In teleost fishes, a recent study on zebrafish Danio rerio (with a polygenic sex determination system) and three-spine stickle back Gasterosteus aculeatus (with a XY sex determination system) reported faster evolution for male-biased genes 6 and similar evidence was also found in the ocellated wrasse, Symphodus ocellatus 7 .…”

“…6,7 . ), synonymous (dS) and non-synonymous substitution (dN) rates were specifically estimated for the S .…”

“…To start dissecting we restricted the analysis to genes showing stronger sex bias (log 2 FC ≥ 3, Fem-FC3 and Male-FC3), considering that highly biased genes, especially male-biased, are expected to have evolved faster 6,7 . In parallel, as the assignment of SB genes may be affected by species-specific factors (e.g., developmental stage, size, and maturity) 32 , we analysed only those genes that are consistently SB in the six sparid and cichlid species (Fem-6-SP and Male-6-SP), i.e., in evolutionarily distant lineages (Fig.…”

“…In S . aurata and in the majority of species where SB genes have been studied, however, female-biased genes have been identified only in mature females 6,7 . Indeed, genes that are consistently overexpressed in mature female gonads in the six teleost species analysed (Fem-6-SP) also had faster evolutionary rates in S .…”