The biological basis of individual differences in aggressiveness

我研究的长期目标是了解侵略性和其他社会行为的个体差异的进化和发展原因。目前，这些人格特征个体差异的近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，胎儿接触睾酮的变化对成年人随后的攻击性，大脑侧化和其他特征具有重要的组织作用。在一个平行的传统中，人们认为母亲的压力激素可以适应性地编程后代，使其发展出最适合他们成长和生活环境的行为压力应对方式。我将通过实验来操纵鱼类的这两种效应，不是在早期发育期间人为地给它们服用激素（一种生物学上不切实际的操纵，可能会产生生物学上不切实际的结果），而是通过尽可能生物学上现实但简单的方法来操纵它们的环境。丽鱼Pelvicachromis pulcher具有pH依赖的性别决定。pH值较低的水产生更多的男性，以及更高比例的男性具有交配繁殖的倾向。我将在生命的前30天使用这些pH值操作来改变鱼的雄性化/雌性化。我也会让发育中的鱼接触化学警报信息素，这是一种天然的压力源，表明捕食者的风险增加。我将研究这些操作对生长速度和成年体型的影响，以及对下丘脑，杏仁核和海马体（参与攻击和压力应对的大脑区域），行为特征（包括恐惧和攻击性）的影响，以及表观遗传效应。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。该计划将机械水平，发展水平和最终水平的问题联系在一起，以了解不同的个性如何发展和发挥作用，为个人更好地生存和繁殖服务。

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.