The social modulation of behavioural profile and stress responsiveness during adolescence: an adaptive mechanisms?

青春期是从童年到成年的逐渐过渡。在生物医学和生物心理科学中，这段时间被认为是一个重要的、危险的、有潜在压力的人生阶段。然而，从进化的角度来看，青春期也可能是一个适应的机会。我们之前对豚鼠的研究表明，在生命的这一阶段，行为特征和应激反应具有明显的环境依赖性。如果雄性在整个青春期生活在大型混合性别群体（COL）中，它们的特征是低攻击性和低（皮质醇）应激反应。相比之下，从青春期早期开始成对生活的雄性（一对；一雄一雌）就非常具有攻击性，表现出高度的应激反应。在第一个资助期，我们专注于潜在的机制，并发现了迄今为止未描述的神经内分泌途径，包括睾酮和应激激素相互作用的核心作用。这个资助期的总体目标是阐明在青春期发生的行为改变是否代表了对个人生活的社会环境的适应。更具体地说，我们认为低攻击性可能是一种“排队策略”的一部分，这种策略使COL能够与不熟悉的同类和平相处，并等待机会垄断雌性。高度侵略性的形象被认为是“资源防御策略”的一部分，帮助PAIR积极地保护他们的女性伴侣。为了验证这一假设，作为原理证明，我们将进行两个匹配-不匹配实验。在实验1中，将创建三元情境（一个男性，一对女性和一个女性）。这些情况反映了低密度的情况，在这种情况下，繁殖成功主要取决于雄性之间竞争的结果。我们假设PAIR（遵循资源防御策略的程序）将比COL占优势，并将产生更多的后代。在相应的实验2中，PAIR和COL被引入到大型混合性别群体中。这种情况反映了一种高密度的情况，即男性繁殖的成功主要取决于“排队策略”。我们假设，COL（遵循排队策略的编程）明显比PAIR更能应对这种情况，因此会产生更多的后代。总之，这个项目是第一个在进化框架内研究青少年行为特征和压力反应的社会调节的项目。来自这两个资助时期的综合见解将为理解社会环境和激素如何以及为什么在生命的这一阶段相互作用以塑造行为特征提供重要的新贡献。

Adolescence is the gradual transition from childhood to adulthood. In the bio-medical and bio-psychological sciences, this time is regarded as an important, dangerous, and potentially stressful life stage. From an evolutionary perspective, however, adolescence may also be an opportunity for adaptation. Our previous work in guinea pigs showed a conspicuous environment-dependent canalization of behavioural profiles and stress responsiveness during this phase of life. If males live in large mixed-sex colonies (COL) throughout adolescence, they are characterized by low aggressiveness and low (cortisol) stress responsiveness. In contrast, males housed in pairs (PAIR; one male / one female) from early adolescence on are very aggressive and show high stress responses. During the 1st funding period we focused on underlying mechanisms and dis-covered a heretofore undescribed neuroendocrine pathway including a central role for the interaction of testosterone and stress hormones. The overall aim of this funding period is to elucidate whether the behavioural alterations that occur during adolescence represent adaptations to the social environment in which the individuals live. More specifically, we argue that the low-aggressive profile may be part of a “queuing strategy” that enables COL to live peacefully with unfamiliar conspecifics and to wait for the opportunity to monopolize females. The highly aggressive profile is supposed to be part of a “resource defence strategy” that helps PAIR to defend their female partners aggressively. To test this hypothesis, as a proof of principle, two match-mismatch experiments will be conducted. In experiment 1, triadic situations will be created (one COL, one PAIR, and a female). These situations reflect a low-density situation, in which reproductive success is deter-mined primarily by the outcome of male-male competition. We hypothesize that PAIR (programmed to follow a resource defence strategy) will be dominant over COL and will sire a higher number of offspring. In the corresponding experiment 2, PAIR and COL are introduced into large mixed-sex colonies. This situation reflects a high-density situation where male reproductive success is mostly determined by a “queuing strategy”. We hypothesize that COL (programmed to follow a queuing strategy) cope distinctly better with this situation than PAIR and will hence sire a higher number of offspring. In summary, this project is among the first to study the social modulation of behavioural profiles and stress responsiveness during adolescence within an evolutionary framework. The combined insights from both funding periods will provide a significant new contribution to the understanding of how and why the social environment and hormones interact during this phase of life to shape behavioural profiles.