Characterizing Androgen and Social Behavior Relationships in Mixed-Sex Groups of Acomys dimidiatus Open Access
Lee, Eunice (Spring 2026)
Abstract
Steroid hormones are long established modulators of social behaviors ranging from social learning and recognition to aggression. Although well-described for estrogens, fewer studies have described the function of androgens like testosterone (T) or androgen receptors (AR) for social behaviors, and even fewer have investigated their role in female organisms. Thus, the current thesis aims to investigate androgen and social behavior relationships in both male and female organisms in the non-territorial spiny mouse (Acomys dimidiatus). We established 5 mixed-sex groups of 7 spiny mice each (n = 35) that were introduced to a novel, enriched environment and recorded for 5 hours over the course of 4 days. Blood and brain samples were collected after the final day of behavioral observations to observe plasma T levels and AR cell densities in the ventromedial hypothalamus (VMH). Behavior was scored every 5 minutes of behavioral recordings for a total of 240 timepoints per animal. T-tests revealed that male spiny mice have significantly higher plasma T levels and VMH AR cell densities than female spiny mice (p < 0.05). Pearson’s correlations revealed that there was no significant correlation between plasma T levels or VMH AR cell densities and observed social behaviors or David’s score (p > 0.05). Assortativity analyses indicate that individuals with a higher David’s score, and thus are more dominant, show more dominance behaviors towards subordinates (p = 0.04), but David’s score does not influence affiliative or investigative behaviors. In addition, no other attributes (kin, sex, AR cell densities, plasma T levels) influence who an individual mouse interacts with. These findings suggest that dominance behaviors and status in spiny mice do not influence or are not influenced by androgens, which is not a common finding in the literature on androgens and dominance. However, it is important to consider methodological differences in the literature, the potential role of other steroid hormones in dominance, and the low overall occurrence of dominance in our current dataset. Despite this, the current thesis contributes to a growing body of literature examining androgen-social behavior relationships in both male and female organisms.
Table of Contents
Introduction…………………………………………………………………………. 1
Method………………………………………………………………………………. 5
Animals……………………………………………………………………… 5
Behavioral Observation……………………………………………………... 6
Behavioral Scoring………………………………………………………….. 8
Social Network Analysis……………………………………………………. 9
Histological Processing……………………………………………………... 10
Androgen Receptor Imaging and Quantification…………………………… 12
Statistics…………………………………………………………………….. 12
Results………………………………………………………………………………. 13
Influence of Sex on Plasma T concentrations and VMH AR cell densities… 13
Androgen – dominance relationships……………………………………….. 13
Androgen – non-dominance behavior relationships………………………… 15
Do social connections form from similarity or dissimilarity? ……………… 16
Discussion………………………………………………………………………….... 18
Dominance and androgens across species…………………………………... 19
Estrogen influences on aggression………………………………………….. 23
A more nuanced perspective of steroid-mediated aggression/dominance….. 24
The role of VMH in modulating aggression/dominance…………………… 24
Conclusion………………………………………………………………………….. 26
About this Honors Thesis
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Characterizing Androgen and Social Behavior Relationships in Mixed-Sex Groups of Acomys dimidiatus () | 2026-04-12 15:16:06 -0400 |
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