Data from: Ontogenetic stage-specific quantitative trait loci contribute to divergence in developmental trajectories of sexually dimorphic fins between medaka populations

Sexual dimorphism can evolve when males and females differ in optimal phenotypic trait values. Several genetic constraints can however limit the evolution of sexual dimorphism. One possible constraint is derived from shared alleles between males and females. Because males and females share most of their genome, shared alleles with different fitness effects between sexes are faced with intra-locus sexual conflict. Another potential constraint is derived from alleles with persistent effects throughout multiple developmental stages; sexually dimorphic traits may increase reproductive success during reproductive periods, but may reduce survival rate during non-reproductive periods, so alleles that increase the expression of sexual dimorphism may be under antagonistic selection between different ontogenetic stages. Resolving intra-locus conflicts between sexes and ontogenetic stages is therefore key for the evolution of age-specific expression of sexual dimorphism. We investigated the genetic architecture of divergence in the ontogeny of sexual dimorphism between two medaka (Oryzias latipes) populations that differ in the magnitude of sexual dimorphism in anal and dorsal fin length. Quantitative trait locus (QTL) mapping revealed that some QTL effect peaks occurred at the beginning of reproduction, while others increased their effects at later reproductive stages, suggesting the presence of ontogenetic stage-specific QTL. Although we found no sex-linked QTL, most QTL were sex-specific suggesting that intra-locus sexual conflict is almost resolved. Our results indicate that the presence of sex and ontogenetic stage-specific QTL enable the populations to achieve optimal developmental trajectories of sexually dimorphic traits in response to complex natural and sexual selection varying among environments.