DOI: 10.5061/dryad.ngf1vhj3t
title: Activational and organizational effects of testosterone on the number of mating partners and reproductive success in males of a social rodent

description: The timing of exposure to the steroid hormone, testosterone, produces
 activational and organizational effects in vertebrates. These activational
 and organizational effects are hypothesized to relate with the number of
 female mating partners and reproductive success in males. We tested this
 hypothesis by examining 151 wild degu (Octodon degus) males across a
 10-year study. We quantified the association between adult serum
 testosterone levels (i.e., an indirect index of adult activational
 effects) and anogenital distance (AGD) length (i.e., a direct index of
 fetal organizational effects), and their interaction on the number of
 female mating partners and reproductive success. We found no evidence of
 an association between adult male serum testosterone levels and the number
 of female mating partners, or between adult male serum testosterone levels
 and reproductive success. However, male AGD was positively associated with
 reproductive success, but not so with the number of female mating
 partners. Additionally, the positive association between male AGD and male
 reproductive success was mediated by the number of mates. Our findings do
 not support major roles of activational or organizational effects of
 testosterone on the number of female mating partners and its consequences
 on male reproductive success. Instead, our results suggest that compared
 with individual male attributes, the female social environment plays a
 more important role in driving male reproductive success.
description: <strong>Results 3.1</strong> To
 test the prediction (i) about the potential effects of male serum
 testosterone levels, male anogenital distance (AGD), and the number of
 females within the social group, and their interactions, on the total
 number of female mating partners, run model model 1. This model run with n
 = 151 replicates, representing all males sampled (i.e., this examination
 included males with zero effective mates). The response variable is Total
 number of female mating partners. To test prediction
 (ii) about the potential effects of male serum testosterone levels, male
 anogenital distance (AGD), and the number of females within the social
 group, and their interactions, on the number of female mating partners
 within the social group, run model model 2. This model run with n = 89
 replicates, representing all males that sired some offspring and whose
 social group included at least one female. The response variable is Number
 of female mating partners within the social group. To
 test prediction (iii) about the potential effects of male serum
 testosterone levels, male anogenital distance (AGD), and the number of
 females within the social group, and their interactions, on the number of
 female mating partners outside the social group, run model model 3. This
 model run with n = 107 replicates, representing all males that bred
 effectively. The response variable is Number of female mating partners
 outside the social group. <strong>Results
 3.2.</strong> To test prediction (iv) about the
 potential effects of male serum testosterone levels, male anogenital
 distance (AGD), and the number of females mating partners, and their
 interactions, on the number of offspring sired by males at weaning, run
 model model 4. This model run with n = 107 replicates, representing all
 males that bred effectively. The response variable is Number of offspring
 sired at weaning. In all models, year and social group
 ID (SGID), were random factors. All other factors were considered fixed
 factors. Serum testosterone does not distribute normally, so it must be
 included transformed with Log10. Model fits were
 assessed with quantile residual dispersion. Best models were chosen by
 their AICc values and average model weight.
description: # Activational and organizational effects of testosterone on the number of
 mating partners and reproductive success in males of a social rodent
 [https://doi.org/10.5061/dryad.ngf1vhj3t](https://doi.org/10.5061/dryad.ngf1vhj3t) Data contained in this file correspond to individual and social group data from a wild population of degus (*Octodon degus*). This file only includes data for adult males. Data corresponds to data from mating season (austral winter), and ten years (2010-2019). ## Description of the data and file structure The file contains only one sheet that can be used to run the four models. Variables included: * Year (individual variable). * Degu ID: Ear tag number or degu identity. Twelve individuals are present two times. For these individuals, each data must be considered as independent data (individual variable). * Sex: M=male (individual variable). * Focal AGD length (mm): is the length of the anogenital distance, expressed in millimeters, of the focal individuals (individual variable). * Body mass (g): is the mean of body mass of focal males (individual variable). * Testosterone level (nmol/L): is the measurement of serum testosterone, expressed in (nmol/L). As the testosterone variable does not have a normal distribution, to work with data, the testosterone variable should be transformed by Log (individual variable). * T Log 10: is the Testosterone level (nmol/L) data but transformed with Log10. We made this transformation because Testosterone levels (nmol/L) does not distribute normally (individual variable). * Group ID (SGID): The number of the social group to which the degu belonged. Alone=males that were not associated with any social group; Male pair= males that were in pairs of males without females. * N° of offspring sired: is the number of pups that each male sire, measured at weaning (individual variable). * Total n° of female mating partners: corresponds to the total number of females with which each male produce offspring (individual variable). * N° of female mating partners within social group: corresponds to the number of females within the social group, with which each male produce offspring (individual variable). * N° of female mating partners outside social group: corresponds to the number of females outside the social group, with which each male produce offspring (individual variable). * Id female mating partners: corresponds to the ids of each female mating partners. This variable is not included in the analysis, in any model. Its function is to quantify the number of total couples, inside and outside the social group. NIM=unidentified mother. Genetically is a different female mating partner, that was not identified in the registry of animals for which we have genetic material data. It possibly corresponds to a female that was not captured and therefore does not have a DNA sample. Blank cells correspond to cells where data do not exist ## Software Analyses were performed in R 4.1.3 (R Core Team 2022). Linear mixed models (LMM) were fitted with the package LME4 1.1-31. DHARMa 0.4.6 and MuMIn 1.46.0 packages were used to perform residual diagnostics and model selection routines, respectively.