Socially induced brain differentiation in a cooperatively breeding songbird

• Published in: Proceedings of the Royal Society. B, Biological sciences Vol. 274; no. 1626; pp. 2645 - 2652
• Main Authors: Voigt, Cornelia, Leitner, Stefan, Gahr, Manfred
• Format: Journal Article
• Language: English
• Published: London The Royal Society 07.11.2007
• Subjects: Androgens; Androgens - blood; Animals; Art songs; Bird songs; Brain; Brain - anatomy & histology; Brain - physiology; Brain Differentiation; Breeding; Cooperative Breeding; Estradiol - blood; Gene Expression Regulation; Male; Male animals; Neurons; Plocepasser mahali; Receptors, Androgen - genetics; Receptors, Androgen - metabolism; Receptors, Estrogen - genetics; Receptors, Estrogen - metabolism; Reproduction - physiology; Social classes; Social Dominance; Social Status; Song Control System; Songbirds; Songbirds - genetics; Songbirds - physiology; Sparrows; Synaptosomal-Associated Protein 25 - genetics; Synaptosomal-Associated Protein 25 - metabolism; Vocal Communication; Vocalization, Animal - physiology
• ISSN: 0962-8452; 1471-2954
• DOI: 10.1098/rspb.2007.0858

Birds living in social groups establish dominance hierarchies, and taking up the dominant position influences behaviour and physiological parameters. In cooperatively breeding white-browed sparrow weavers (Plocepasser mahali), the transition from subordinate helper to dominant breeder male induces the production of a new type of song. This song contains a large number of new syllables and differs in temporal pattern from duet songs produced by all other group members. Here we show that this change in social status of adult males affects the morphology of a behavioural control circuit, the song control system of songbirds that is composed of large neuron populations. The volume of the song control areas HVC and RA and their gene-expression levels depend on males' social status. Dominant males have several times larger testes than subordinates, which is not reflected in circulating androgen and oestrogen levels. Our findings suggest a remarkable differentiation of adult vertebrate brains in relation to changing social cues.