Social influences during adolescence on adult behaviour in zebra finches: endocrine mechanisms and functional consequences

青春期是一个人达到性成熟并独立于父母的关键人生阶段。对哺乳动物的研究表明，这一过渡时期的社会环境可能对个体成年后应对社会和其他挑战的方式产生终身影响。在过去的几年里，我们调查了青春期的社会环境是否对鸟类的成年行为具有类似的重要性。雄性斑胸草雀在青春期与一只雌性斑胸草雀一起长大，表现出更多的求偶和攻击行为，最初比群体饲养的雄性斑胸草雀（3只雄性和3只雌性）更具吸引力。四个月后，求偶和攻击性方面的差异仍然存在，尽管略有减弱，但雄性在吸引力方面不再存在差异。由于求爱和竞争行为的成本和收益取决于社会环境，这些影响可能代表了他们在青春期经历的对社会环境的适应性行为反应。我们的观察结果与早期在豚鼠身上的发现相似，表明这一普遍现象并不局限于哺乳动物，可能也具有类似的潜在机制和适应功能。因此，本研究的主要目的是研究青少年时期社会经历的长期影响的机制和适应价值。首先，我们将更详细地描述个体在青春期处于不同社会环境时的激素特征和行为，以及当遇到潜在伴侣、竞争对手或身体压力源（固定）时，这些变化对行为和激素反应的后续影响。然后，我们将通过评估成年期不同社会环境下的健康成本和收益（相关因素），研究观察到的对求爱和攻击性的长期影响的功能后果。通过激素操纵（在早期发育和成年生活中阻断受体和操纵激素），我们进行了实验测试，是否建议的激素机制确实可以解释观察到的对行为的长期影响。

Adolescence is the key life history stage during which an individual reaches sexual maturity and becomes independent from its parents. Studies on mammals show that the social environment during this transitional period can have life-long consequences for the way in which individuals cope with social and other challenges as adults. During the past years, we investigated whether the social environment during adolescence is of similar importance for adult behaviour of birds. Male zebra finches growing up with a single female during adolescence showed more courtship and aggressive behaviour and were initially more attractive than group-reared males (3 males and 3 females). Four months later, the differences in courtship and aggressiveness persisted, albeit slightly diminished, but the males no longer differed in attractiveness. Since costs and benefits of courtship and competitive behaviour depend on the social context, these effects may represent adaptive behavioural responses to the social environment due to their experiences during adolescence. Our observations resemble earlier findings in guinea pigs suggesting a general phenomenon not restricted to mammals with potentially also similar underlying mechanisms and adaptive function. The key objective of the current proposal is therefore to study the mechanisms and the adaptive value of the long-term effects of social experiences during adolescence. First, we will describe in more detail the hormonal profiles and behaviour while individuals are kept during adolescence in different social environments and the subsequent consequences of these changes for behavioural and hormonal response when encountering a potential mate, competitor or a physical stressor (immobilisation). We will then study the functional consequences of the observed long-term effects on courtship and aggressiveness by assessing (correlates of) fitness costs and benefits in different social settings during adulthood. Using hormonal manipulations (blocking receptors and manipulating hormones during early development and adult life) we fill experimentally test whether the suggested hormonal mechanisms can indeed explain the observed long-term effects on behaviour.