DOI: 10.5061/dryad.6djh9w16h
title: Social environment and masculinization level interact to explain male testosterone levels in a social rodent: Part 1: The male side

description: In vertebrates, male testosterone levels vary across the year being
 generally higher during the mating relative to the offspring rearing
 season. However, male testosterone levels may also be influenced by male
 anogenital distance (AGD) length (a proxy of prenatal androgen
 exposition), and by the social group environment. In social species, it
 has been proposed that high levels of testosterone could be incompatible
 with the development of an amicable social environment. Thus, in these
 species, it is predicted that males have relatively low levels of
 testosterone. Our goal was to examine the potential association between
 male serum testosterone levels, male AGD length, and the social
 environment in the rodent Octodon degus under natural conditions. We
 quantified male serum testosterone levels during the mating and
 offspring-rearing seasons, and we determined the number of females and
 males in each social group, as well as the composition of groups, in terms
 of the AGD length of the female and male group mates, from 2009 to 2019.
 Our results revealed that male testosterone levels covary with the season,
 being highest during offspring rearing season. Additionally, male
 testosterone levels vary with male AGD length and female and male social
 group environments. More importantly, male degus exhibit low levels of
 testosterone that are indistinguishable from female levels during
 offspring-rearing season. Similar to other highly social mammals, where
 males and females live together all year, male amicable behavior could be
 the best male mating strategy, having as a proximal mechanism, a reduction
 in circulating testosterone levels.
description: # Data for: **SOCIAL ENVIRONMENT AND MASCULINIZATION LEVEL INTERACT TO
 EXPLAIN TESTOSTERONE LEVELS IN A COMMUNALLY REARING RODENT: PART 1: THE
 MALE SIDE** https://doi.org/10.5061/dryad.6djh9w16h ## Summary of dataset
 contents, contextualized in experimental procedures and results. Data
 contained in this file correspond to individual and social group data from
 a wild population of degus (*Octodon degus*) and include data from two
 seasons (mating and offspring rearing) and eleven years (from 2009 to
 2019). For model 1, use testosterone data from both sheets (1 and 2). For
 model 2, use data from sheet 1. For model 3, use data from sheet 2. ####
 Results 3.1. To test the prediction (i) about focal male serum
 testosterone levels vary across reproductive season, run model model 1.
 #### Results 3.2. To test predictions (ii and iii) about that potential
 effects of male AGD phenotype, number of females, and mean group female
 AGD, on male testosterone levels during mating season, run model 2.1. To
 test predictions (ii and iv) about that potential effects of male AGD
 phenotype, number of males, and mean group male AGD, on male testosterone
 levels during mating season, run model 2.2. #### Results 3.3. To test
 predictions (v and vi) about that potential effects of male AGD phenotype,
 number of females, and mean group female AGD, on male testosterone levels
 during offspring rearing season, run model 3.1. To test predictions (v and
 vi) about that potential effects of male AGD phenotype, number of males,
 and mean group male AGD, on male testosterone levels during offspirng
 season, run model 3.2. In all models, log-transformed testosterone is the
 response variable. Season, focal male AGD, N of males, N of females, mean
 group female AGD, and mean group male AGD, were fixed factors. Year, Degu
 ID, were random factors. Model 1-2-3 included the year of study and degu
 identity (Degu ID) as random factors. Model fits were assessed with
 quantile residual dispersion. Best models were chosen by their AICc values
 and average model weight. ### Description of the data and file structure
 The file contains two sheets with data: Sheet 1: mating season data. Sheet
 2: offspring season period data. Data from mating period include data from
 2010 to 2019. Data from offspring-rearing period include data from 2009 to
 2019. Blank cells corresponds to cells were data do not exists Variables
 included: * Year (individual variable). * Degu ID: Ear tag number or degu
 identity. Some individuals are present several times (2-5 times). For
 these individuals, each data must be considered as independent data
 (individual variable). * Sex: F= female/M=male (individual variable). *
 Group ID: The number of the social group to which the degu belonged. Some
 males were alone, these males should be included in model 1. Model 2 and 3
 that include the analysis of the n of males and females and mean group
 males and female AGD variables, should be run without data from males that
 were alone (Social group variable). * N of females: is the total number of
 females in each social group (Social group variable). * N of males: is the
 total number of males in each social group (Social group variable). *
 Focal AGD (mm): is the length of the anogenital distance, expressed in
 millimeters, of the focal individuals (individual variable). * Mean group
 female AGD (mm): the mean AGD of female group mates, expressed in
 millimeters (social group variable). * Mean group male AGD (mm): the mean
 AGD of male group mates after excluding the focal male AGD. Expressed in
 millimeters (Social group 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). #### Freeform section for describing any code in your
 submission and the software used to run it. 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.
 https://doi.org/10.5061/dryad.6djh9w16h