DOI: 10.5061/dryad.dv41ns1vj
title: Seasonal change in male reproductive investment of a fish

description: Many animals are sexually dimorphic, whereby males may display brighter
 body coloration and more distinctive ornamentation than females. Fishes in
 temperate regions markedly change their energy allocation toward
 reproduction in response to the seasonal environment. Seasonal change in
 reproductive investment affects the expression of sexually dimorphic
 traits in males through gonadal weight change. Here, we report seasonal
 changes in body size, testis weight and sexual dimorphism of the fins
 (anal fin length and dorsal fin length) in the northern medaka Oryzias
 sakaizumii. Fish were collected periodically from a wild population
 (Aomori). Gonad weight increased from May to July in both males and
 females, corresponding to the reproductive season. Moreover, during this
 period, the degree of sexual dimorphism in fin length increased. To
 investigate the relationship between testis weight and individual
 differences in male fin length, we analyzed relationships among
 morphological traits using structural equation modeling. In the
 reproductive season, increased testis weight was associated with longer
 fin length in males, but the relationship disappeared after the
 reproductive season. These observations suggest that the sexually
 dimorphic fin in this fish is a mating signal. Results from a mating
 experiment also support this view. Males with larger size and/or longer
 fin attracted more mates than those with smaller fins, suggesting that
 sexual selection operates through females choosing to mate with males
 having longer fins.
description: Seasonal change in Gonad-soma index(GSI)<br>  |-------
 aomoriGSI_data2004.csv(2020/04/01): Wild individual's morphological
 data, standard length, anal fin length, body weight, and gonad
 weight<br>  |------- Fig2_seasonalChange_BW_GSI.R(2020/04/01):
 Boxplot of the seasonal change in GSI<br>  |-------
 Fig4_TableS2_SEM_BW_SL_TW_AFL.R(2020/04/01): The association among
 morphological traits using structural equation modeling.
 Seasonal change in sexual dimorphism in fins, anal-fin
 length(AFL), and dorsal-fin length(DFL)<br>  |-------
 aomoriGSI_data2004.csv(2020/04/01): Wild individual's morphological
 data, standard length, anal fin length, body weight, and gonad
 weight<br>  |------- SLvsFin_Data2013.csv(2020/04/01): Wild
 individual's morphological data, standard length, body depth, anal
 fin length, and dorsal fin length.<br>  |-------
 Fig3_seasonalChange_AFLandDFLratio.R(2020/08/07): The ratio in AFL or DFL
 per standard length  Mating experiment to test the
 effect of male morphology on reproductive success<br>  |-------
 mateNumberAndfertilizationRate.csv(2020/08/14): Egg number, fertilization
 rate, female size, and male morphological traits in the mating
 experiment<br>  |------- Table1_FigS3_mateNumber.R (2020/08/14):
 Wald test for the mate number and male morphological traits<br>
  |------- Table1_FigS4_fertilizationRate.R(2020/08/14):  Wald test for the
 fertilization rate and male morphological traits #
 --------------------------------------------------------------------------------------------------------------<br> # Sharing and access information<br> # -------------------------------------------------------------------------------------------------------------- Users are free to use the database and its content in new and different ways,<br> provided they provide attribution to the source of the data and/or the database. # --------------------------------------------------------------------------------------------------------------<br> # Methodological information: (reference)<br> # --------------------------------------------------------------------------------------------------------------<br> Description of methods for data collection or generation: https://doi.org/10.1007/s10641-021-01059-x<br> The R scripts were written and performed using R version 3.6.1 for Windows (R Core Team, 2019, www.r-project.org/).
description: aomoriGSI_data2004.csv (2020/04/01)<br>                    
    |-- year: Year of fish collection<br>                        |--
 month: Month of fish collection<br>                        |--
 ordinal: Julian date of fish collection<br>                      
  |-- collectDate: The date of fich collection(YYYY/MM/DD)<br>      
                  |-- picID: picture ID for morphological
 measurement<br>                        |-- individualID: individual
 ID for morphological measurement<br>                        |-- sex:
 "f" is female, and "m" ins male<br>            
            |-- SLmm: Standard length (mm)<br>                      
  |-- AFLmm: Anal fin length (mm)<br>                        |--
 BW_fol: Formalin-fixed body weight (gram)<br>                      
  |-- gonadW: Gonad weight (gram)<br>                        |-- GSI:
 Gonad-soma index, 100 * Gonad weight per Formalin-fixed body
 weight SLvsFin_Data2013.csv (2021/02/15)<br>    
                    |-- date: The date of fich
 collection(YYYY/MM/DD)<br>                        |-- year: Year of
 fish collection<br>                        |-- month: Month of fish
 collection<br>                        |-- ordinal: Julian date of
 fish collection<br>                        |-- population: collected
 site name<br>                        |-- sex: "f" is
 female, and "m" ins male<br>                        |--
 SL: Standard length (mm)<br>                        |-- BD: Body
 depth (mm)<br>                        |-- AFL: Anal fin length
 (mm)<br>                        |-- DFL: Dorsal fin length
 (mm)<br>                        <br>
 mateNumberAndfertilizationRate.csv (2020/08/14)<br>                
        |-- collectDate: The date of fich collection(YYYYMMDD)<br>  
                      |-- fID: Female individual ID for mating
 experiment<br>                        |-- sizeF: Female standard
 length (mm)<br>                        |-- reproduct: "1"
 is spawning egg in the mating experiment, and "0" is  not
 spawing.<br>                        |-- Fegg: number of
 fertilization egg<br>                        |-- NonFegg: number of
 non-fertilization egg<br>                        |-- mID: Male
 individual ID for mating experiment<br>                        |--
 SL: Male standard length (mm)<br>                        |-- TL:
 Male total length (mm)<br>                        |-- BD: Male body
 depth (mm)<br>                        |-- CFL: Male caudal fin
 length (mm)<br>                        |-- AFL: Male anal fin length
 (mm)<br>                        |-- DFL: Male dorsal fin length
 (mm)<br>                        |-- AFLratio: Male anal fin length
 per standard length<br>                        |-- DFLratio: Male
 dorsal fin length per standard length