Group size, temperature and body size modulate the effects of social hierarchy on basal cortisol levels in fishes

Type Article
Date 2021-11
Language English
Author(s) Bessa Eduardo1, Sadoul Bastien2, 3, McKenzie David4, Geffroy Benjamin3
Affiliation(s) 1 : Graduate Program in Ecology, Universidade de Brasília, Distrito Federal, Brazil
2 : ESE, Ecology and Ecosystem Health, Institut Agro, INRAE, Rennes, France
3 : MARBEC, Univ Montpellier, Ifremer, CNRS, IRD, Palavas-Les-Flots, France
4 : MARBEC, Univ Montpellier, Ifremer, CNRS, IRD, Palavas-Les-Flots, France
Source Hormones And Behavior (0018-506X) (Elsevier), 2021-11 , Vol. 136 , P. 105077 (6p.)
DOI 10.1016/j.yhbeh.2021.105077
WOS© Times Cited 6
Keyword(s) Stress, Aggressiveness, Sociality, Shoal, Meta-analysis

Social rank in a structured society has been linked to basal levels of glucocorticoids in various species, with dominant individuals generally presenting lower levels than subordinates. The biotic and abiotic factors influencing glucocorticoids levels across social ranks are still, however, unclear in fishes. We investigated the influences of group size, fish size, sex, age, and reproduction type, plus water salinity and temperature, on the basal levels of cortisol, the major stress hormone in fishes. A phylogenetically controlled meta-analysis was performed on data from 72 studies over 22 species of fishes. As expected, dominants generally exhibited lower levels of cortisol than subordinates. More importantly, the strength of the correlation between cortisol and rank was modulated by three main factors, group size, environmental temperature, and fish size. Differences in basal cortisol between dominants and subordinates were significantly greater in small groups (dyadic contexts) when compared to larger groups. Differences between dominants and subordinates were also greater in temperate regions when compared to the tropics, and in species with larger body size. These results provide valuable insights into the links among hierarchy, stress and metabolism in fishes.

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