Social influences during adolescence on adult behaviour in zebra finches: endocrine mechanisms and functional consequences
Final Report Abstract
Evidence for potentially adaptive modifications of development by social influences during adolescence originates mainly from research on mammals, although it is known that social experiences during the transition to independence can have long-lasting influences on offspring traits also in birds. Our studies focus on the zebra finch, a monogamous species that pairs for life, but breeds in colonies with frequent social interactions. These social and sexual behaviours may clearly be influenced by social experiences during adolescence, due to their known impact on sexual imprinting and song learning, but also possibly mediated by organisational effects of hormones during development. Our studies report strong, presumably permanent effects of the adolescent social environment on adult sexual and social behaviour in zebra finches. Males reared with a single female during adolescence court more and are more aggressive towards potential competitors than group-reared males. Pair-reared males are also initially most attractive to females. On the other hand, pair-reared males integrate less well into a social group, received more aggression and lost more weight when integrating into a new group. Some of these effects are stable over several months and not changed by adult social experience. As reported for guinea pigs, these behavioural differences appear to go together with differences in corticosterone baseline and challenge levels. In match-mismatch experiments we tested whether male reproductive success is maximised at social densities matching the social densities during adolescence, but found to our surprise the opposite. Group-reared males obtain more offspring when competing with a pair-reared male over a single female, whereas pairreared males outperformed them when competing in small groups of 5 males and 4 females. In a follow up experiment we found the expected lower reproductive success of males reared in pairs when birds competed in very large groups. While these results show that the adolescent social environment can have strong fitness consequences, we clearly need further study of the potential adaptive benefits. Overall, the results show that social conditions during adolescence shape behavioural and physiological development with long-lasting effects on adult behaviour and consequences for reproductive success. As in other vertebrates, organizational effects of testosterone and changes in the adult stress response may be involved, although evidence from experimental manipulation of hormones is still lacking. Some of the observed effects, particularly increased courtship and aggressive behaviour in pair-reared as compared to group-reared males show a striking resemblance to the effects observed in similar experiments on guinea pigs. These parallels between a mammal and a bird species indicate potentially similar underlying hormonal and behavioural mechanisms, which may even generalize across a larger range of vertebrate taxa, as the early social environment affects adult social behaviour for example also in fish.
Publications
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(2013) Adolescent social environment shapes sexual and aggressive behaviour of adult male zebra Finches (Taeniopygia guttata). Behavioral Ecology and Sociobiology 67: 175-184
Ruploh, T. Bischof, H.-J., von Engelhardt, N.
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(2013) Early social instability affects plasma testosterone during adolescence but does not alter reproductive capacity or measures of stress later in life. Physiology & Behavior 120:143-149
Siegeler, K. Wistuba, J. Damm, O.S., von Engelhardt, N., Sachser, N., Kaiser, S.
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(2014). Social experience during adolescence influences how male zebra finches (Taeniopygia guttata) group with conspecifics. Behavioral Ecology and Sociobiology 68: 537-549
Ruploh, T. Bischof, H.-J., von Engelhardt, N.
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(2015) Effects of social conditions during adolescence on courtship and aggressive behavior are not abolished by adult social experience. Developmental Psychobiology
Ruploh, T. Bischof, H.-J., von Engelhardt, N.
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(2015) The maternal social environment shapes offspring growth, physiology, and behavioural phenotype in guinea pigs. Frontiers in Zoology, 2015, 12 (Suppl 1):S13
von Engelhardt N, Kowalski G J, Guenther A
