The biological basis of individual differences in aggressiveness

我研究的长期目标是了解攻击性和其他社会行为的个体差异的进化和发展原因。目前，这些人格特征的个体差异的直接原因和发展原因还没有得到很好的理解。子宫环境被认为是影响哺乳动物成年人格的一个因素。心理学家和生物学家认为，胎儿睾酮暴露水平的变化对成年后的攻击性、大脑偏侧和其他特征有重要的组织影响。在一个平行的传统中，人们认为母亲的压力激素可能会适应性地编程后代，使其发展出最适合他们成长和生活的环境的行为压力应对方式。我将在鱼身上实验操纵这两种效应，不是通过在鱼的早期发育过程中人为地给它们注射激素（一种生物学上不现实的操纵，可能会产生生物学上不现实的结果），而是通过尽可能以生物学上现实而简单的方法操纵它们的环境。慈鲷Pelvicachromis pulcher显示ph依赖性性别决定。pH值较低的水产生更多的雄鱼，并且有更高比例的雄鱼倾向于近亲繁殖。我将在鱼出生后的第30天使用这些pH值操作来改变鱼的雄性化/雌性化。我还会让发育中的鱼接触一种化学警报信息素，一种表明捕食者风险增加的自然压力源。我将研究这些操作对生长速度和成人体型的影响，以及对下丘脑、杏仁核和海马体（涉及攻击性和应对压力的大脑区域）、行为特征（包括恐惧和攻击性）和表观遗传效应的影响。我将通过测试鱼类在社会环境中的表现来衡量这些差异的进化成本和收益。该课程将机械水平、发展水平和终极水平的问题联系在一起，以了解不同人格是如何发展和发挥作用的，从而为个体更好地生存和繁殖提供服务。

The long term goal of my research is to understand the causes, both evolutionary and developmental, of individual differences in aggressiveness and other social behaviours. At present the proximate and developmental causes of individual differences in such personality traits are not well understood. One factor thought to influence adult personality in mammals is uterine environment. Psychologists and biologists believe that variation in fetal exposure to testosterone has an important organizing effect on subsequent aggressiveness, brain lateralization and other traits among adults. In a parallel tradition, it is thought that maternal stress hormones may adaptively program offspring into developing a behavioural stress coping style best suited to the environment they will grow up and live in. I will experimentally manipulate both these effects in fish, not by artificially dosing them with hormones during early development (a biologically unrealistic manipulation which may produce biologically unrealistic results) but by manipulating their environment in as biologically realistic, yet simple, a method as possible. The cichlid fish Pelvicachromis pulcher shows pH-dependent sex determination. Lower pH water produces more males, and a higher proportion of males with a tendency to haremic breeding. I will use these pH manipulations in the 30 first days of life to vary the masculinization/feminization of fish. I will also expose developing fish to a chemical alarm pheromone, a natural stressor indicating elevated predator risk. I will examine the effects of these manipulations on growth rates and adult body shape, as well as effects on the hypothalamus, amygdala and hippocampus (brain areas involved in aggression and stress coping), behavioural traits (including fearfullness and aggressiveness), and epigenetic effects. I will measure the evolutionary costs and benefits of these differences by testing how fish fare in social situations. This programme ties together questions at the mechanistic level, the developmental level, and the ultimate level to understand how different personalities develop and function to serve individuals to better survive and reproduce.