The biological basis of individual differences in aggressiveness

我的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原因，无论是进化的还是发展的。目前，这类人格特质个体差异的直接原因和发展原因还不是很清楚。影响哺乳动物成年人格的一个因素是子宫环境。心理学家和生物学家认为，胎儿接触睾酮的变化对随后的攻击性、大脑偏侧化和成年人的其他特征具有重要的组织效应。在一个平行的传统中，人们认为母亲的压力荷尔蒙可能会适应性地让后代发展出一种最适合他们成长和生活环境的行为压力应对方式。我将在实验中操纵鱼的这两种效应，不是通过在鱼的早期发育过程中人为地给它们注射激素(这是一种在生物学上不现实的操作，可能会产生生物学上不现实的结果)，而是通过尽可能在生物上真实但又简单的方法来操纵它们的环境。慈鱼Pelvicchchrois Pulcher表现出依赖于pH的性别决定。低pH值的水会产生更多的雄性，并且有繁殖血统倾向的雄性比例更高。我将在生命的前30天使用这些酸碱度控制来改变鱼的雄性化/雌性化。我还将把发育中的鱼暴露在一种化学警报信息素中，这是一种自然应激源，表明捕食者的风险增加。我将研究这些手法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(参与攻击性和压力应对的大脑区域)、行为特征(包括恐惧和攻击性)以及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。这个项目将机制层面、发展层面和终极层面的问题联系在一起，以了解不同的个性如何发展和发挥作用，为个体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.