Social environment and masculinization level interact to explain testosterone levels in a communally rearing rodent: part 2: the female side
Data files
Oct 11, 2023 version files 71.64 KB
Dec 18, 2023 version files 99.21 KB
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Female_testosterone_data.xlsx
95.14 KB
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README.md
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Abstract
Testosterone is known as a “male” hormone; however, females also synthetize testosterone, which influences female sexual and aggressive behavior. In female vertebrates, season affects female testosterone levels as consequence of adrenal activation during the nursing season, as females are undergoing high energetic demands. However, female testosterone levels may also be related with female anogenital distance (AGD) phenotype (a proxy of prenatal androgen exposition), and the social group environment. We used data from a long-term rodent study (2009–2019) in a natural population of degus (Octodon degus) to examine the potential associations between female serum testosterone levels, season, female AGD phenotype, and social group composition. We quantified female serum testosterone levels during the mating and offspring rearing seasons, and we determined the number of females and males in social groups, as well the composition of groups, in terms of the AGD of the female and male group mates. Our results indicate that female testosterone levels vary with season, being highest during the offspring rearing season. Additionally, female testosterone levels were associated with the number of male group-members and the AGD of male group-members but were not associated with female social environment and focal female AGD phenotype. Together, our results suggest that female testosterone levels are sensitive to intersexual interactions. Our results also reveal that female and male testosterone levels do not differ between the sexes, a finding previously reported only in rock hyraxes. We discuss how the complex social system of degus could be driving this physiological similarity between the sexes.
README: SOCIAL ENVIRONMENT AND MASCULINIZATION LEVEL INTERACT TO EXPLAIN TESTOSTERONE LEVELS IN A COMMUNALLY REARING RODENT: PART 2: THE FEMALE SIDE
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 female 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 female AGD phenotype, number of females, and mean group female AGD, on female testosterone levels during mating season, run model 2.1. To test predictions (ii and iv) about that potential effects of female AGD phenotype, number of males, and mean group male AGD, on female testosterone levels during mating season, run model 2.2.
Results 3.3.
To test predictions (v and vi) about that potential effects of female AGD phenotype, number of females, and mean group female AGD, on female testosterone levels during offspring rearing season, run model 3.1. To test predictions (v and vi) about that potential effects of female AGD phenotype, number of males, and mean group male AGD, on female testosterone levels during offspirng season, run model 3.2.
In all models, log-transformed testosterone is the response variable. Season, focal female 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 rearing season data.
Data from mating season include data from 2010 to 2019. Data from offspring-rearing season 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 females were alone, these females 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 females 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.