2023 Volume 40 Issue 2 Pages 105-112
Sexual dimorphism, the phenotypic differences between males and females, is prevalent but rapidly diversified within and among species. It has been known that sexual selection, an evolutionary process driven by competition for mates with the opposite sex, plays important roles in the evolution of sexually dimorphic traits. However, few studies have identified the genes responsible for the diversification of sexual dimorphism, and thus the detailed genetic mechanisms underlying the sex-biased expression of the responsible genes and the detailed processes by which the novel alleles can be spread within populations remain unknown. In this review, we focus on medaka fishes (the family Adrianichthyidae) endemic to Sulawesi, Indonesia, which exhibits a remarkable diversity in sexual dimorphic traits, as an experimental model system for studying the evolution of sexual dimorphism. We present our recent study on the red nuptial coloration found in the male pectoral fins of Oryzias woworae as a practical case study. Furthermore, we highlight the potential advantages of the Sulawesian medaka fishes as a model system for comparative biology and other research fields.
