Inter-population variation in fin sexual dimorphism in medaka (Oryzias latipes)

Multiple factors can influence the strength of sexual selection in populations; variation in these factors can result directly or indirectly from environmental factors, including climatic ones, and this variation can, in turn, result in among-population variation in the strength of sexual selection. Populations with intense sexual selection can have greater divergence between the sexes for sexually selected traits, but this is less likely for traits that are not under sexual selection. In this study, taking advantage of a cline in conditions that could impact the strength of sexual selection, we asked which environmental factors best predicted among-population variation in the degree of sexual dimorphism in sexually selected traits. We predicted that populations with environmental factors that extend the length of the breeding season would have increased sexual dimorphism in those traits; this is because, as the breeding season gets longer, the receptivity of the sexes can become asynch..., , , **Data files required to reproduce Downer-Bartholomew and Rodd (2025): Inter-population variation in fin sexual dimorphism in medaka (*Oryzias latipes*).**

This file contains the data needed to reproduce the statistical analyses presented in Downer-Bartholomew and Rodd (2025). Each column contains a different variable, see the list below for details on each. Each row contains the values and details for a given specimen (N = 284).

**File name: DownerBartholomew and Rodd 2025_Specimen Data.csv**

Column name: Description

Specimen: Unique specimen number. Provided by Kanagawa Prefecture Natural History Museum (KPMNH).

Subpopulation: Subpopulation the specimen belongs to. Provided by KPMNH.

District: District-prefecture that the specimen was collected from. Provided by KPMNH.

City: City that the specimen was collected from. Provided by KPMNH.

Town: Town that the specimen was collected from. Provided by KPMNH.

WaterBody: Water body/river that the specimen was collected from. Provided...,