Effect of the early social environment on behavioural and genomic responses to a social challenge in a cooperatively breeding vertebrate.
The early social environment can have substantial, lifelong effects on vertebrate social behaviour, which can be mediated by developmental plasticity of brain gene expression. Early-life effects can influence immediate behavioural responses towards later-life social challenges and can activate different gene expression responses. However, while genomic responses to social challenges have been reported frequently, how developmental experience influences the shape of these genomic reaction norms remains largely unexplored. We tested how manipulating the early social environment of juvenile cooperatively breeding cichlids, Neolamprologus pulcher, affects their behavioural and brain genomic responses when competing over a resource. Juveniles were reared either with or without a breeder pair and a helper. Fish reared with family members behaved more appropriately in the competition than when reared without. We investigated whether the different social rearing environments also affected the genomic responses to the social challenge. A set of candidate genes, coding for hormones and receptors influencing social behaviour, were measured in the telencephalon and hypothalamus. Social environment and social challenge both influenced gene expression of egr-1 (early growth response 1) and gr1 (glucocorticoid receptor 1) in the telencephalon and of bdnf (brain-derived neurotrophic factor) in the hypothalamus. A global analysis of the 11 expression patterns in the two brain areas showed that neurogenomic states diverged more strongly between intruder fish and control fish when they had been reared in a natural social setting. Our results show that same molecular pathways may be used differently in response to a social challenge depending on early-life experiences.
Division of Behavioural Ecology, Institute for Ecology and Evolution, University of Bern, Wohlenstrasse 50A, CH-3032, Hinterkappelen, Switzerland.
Cecilia
http://orcid.org/0000-0002-4604-4610
C
Nyman
Institute of Integrative Biology, University of Liverpool, Leahurst Campus, Chester High Road, Neston, CH64 7TE, UK.
Stefan
S
Fischer
Département de Biologie et Institut de Biologie Intégrative et des Systèmes, Université Laval, Quebec, Canada, G1V OA6.
Nadia
N
Aubin-Horth
Division of Behavioural Ecology, Institute for Ecology and Evolution, University of Bern, Wohlenstrasse 50A, CH-3032, Hinterkappelen, Switzerland.
Barbara
B
Taborsky
D000818:Animals; D001522:Behavior, Animal; D001947:Breeding; D023681:Cichlids / Q000235:genetics* / Q000502:physiology*; D029941:Fish Proteins / Q000235:genetics; D012919:Social Behavior; D012931:Social Environment
D029941:Fish Proteins
behavioural flexibility; brain gene expression; cooperative breeder; developmental plasticity; early social environment; genomic reaction norm; neurogenomic state; social challenge; social competence