Data from: Natural allelic variations of xenobiotic metabolizing enzymes affect sexual dimorphism in Oryzias latipes

Sexual dimorphisms, which are phenotypic differences between males and
females, are driven by sexual selection. Interestingly, sexually selected
traits show geographical variations within species despite strong
directional selective pressures. This paradox has eluded many evolutionary
biologists for some time, and several models have been proposed (e.g.
‘indicator model’ and ‘trade-off model’). However, disentangling which of
these theories explains empirical patterns remains difficult, because
genetic polymorphisms that cause variation in sexual differences are still
unknown. In this study, we show that polymorphisms in cytochrome P450
(CYP) 1B1, which encodes a xenobiotic-metabolizing enzyme, are associated
with geographical differences in sexual dimorphism in the anal fin
morphology of medaka fish (Oryzias latipes). Biochemical assays and
genetic cross experiments show that high- and low-activity CYP1B1 alleles
enhanced and declined sex differences in anal fin shapes, respectively.
Behavioural and phylogenetic analyses suggest maintenance of the
high-activity allele by sexual selection, whereas the low-activity allele
possibly has experienced positive selection due to by-product effects of
CYP1B1 in inferred ancestral populations. The present data can elucidate
evolutionary mechanisms behind genetic variations in sexual dimorphism and
indicate trade-off interactions between two distinct mechanisms acting on
the two alleles with pleiotropic effects of xenobiotic-metabolizing
enzymes.