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Collective action reduces androgen responsiveness with implications for shoaling dynamics in stickleback fish

Ines Fuertbauer Orcid Logo, Rowan Brown Orcid Logo, Michael Heistermann

Hormones and Behavior, Volume: 119, Start page: 104636

Swansea University Authors: Ines Fuertbauer Orcid Logo, Rowan Brown Orcid Logo

Abstract

Androgens, traditionally viewed as hormones that regulate secondary sexual characteristics and reproduction in male vertebrates, are often modulated by social stimuli. High levels of the ‘social hormone’ testosterone (T) are linked to aggression, dominance, and competition. Low T levels, in contrast...

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Published in: Hormones and Behavior
ISSN: 0018-506X
Published: Elsevier BV 2020
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa52635
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Abstract: Androgens, traditionally viewed as hormones that regulate secondary sexual characteristics and reproduction in male vertebrates, are often modulated by social stimuli. High levels of the ‘social hormone’ testosterone (T) are linked to aggression, dominance, and competition. Low T levels, in contrast, promote sociopositive behaviours such as affiliation, social tolerance, and cooperation, which can be crucial for group-level, collective behaviours. Here, we test the hypothesis that - in a collective context - low T levels should be favourable, using non-reproductive male and female stickleback fish (Gasterosteus aculeatus) and non-invasive waterborne hormone analysis. In line with our predictions, we show that the fishes' T levels were significantly lower during shoaling compared to when alone, with high-T individuals showing the largest decrease. Ruling out stress-induced T suppression and increased T conversion into oestradiol, we find evidence that shoaling directly affects androgen responsiveness. We also show that groups characterized by lower mean T exhibit less hierarchical leader-follower dynamics, suggesting that low T promotes egalitarianism. Overall, we show that collective action results in lower T levels, which may serve to promote coordination and group performance. Our study, together with recent complementary findings in humans, emphasizes the importance of low T for the expression of sociopositive behaviour across vertebrates, suggesting similarities in endocrine mechanisms.
Keywords: Collective hormone profiles, Social context, Social modulation, Social tolerance, Testosterone
College: Faculty of Science and Engineering
Start Page: 104636