Environmental sex determination, alternative male morphs, and the biological basis of personality

我的实验室专注于理解类人格特征的生物学基础，尤其是攻击性。我们研究了这种个体差异背后的进化、发展和神经内分泌机制。我们的目标是了解维持行为变化的进化成本和收益。***在发育过程中，产前睾酮暴露的变化被认为永久性地组织了整个成年期的许多行为，特别是那些表现出性别差异的行为，形成了一个大脑性别谱。来自人类和非人类动物的经验证据表明，性别分化的强度可以不同地使最终成年的形态和行为变得男性化。大部分的工作都是纯粹相关的。如果产生的表型超出了最近祖先历史的范围，那么实验操作，如发育期间的激素治疗，并不一定能告诉我们变异的选择压力。***为了创造这种真实世界的范围变化，我将以一种生态现实的方式实验性地操纵性别，通过操纵一种慈鲷鱼的水化学成分来决定环境性别。意图是在个体的男性化程度上创造变异。在头30天内较低的pH值会在成年期产生更多的雄性，而且这些雄性中更多的是更具攻击性的、倾向于哈妻制的，而更少的是倾向于一夫一妻制的。***在许多其他具有环境性别决定的物种中进行的研究表明，芳香化酶基因启动子的甲基化与环境因素有关，是性别决定的关键部分。我的初步数据表明，早期的pH操作影响了芳香酶基因的脑和性腺版本启动子中CpG位点的甲基化。我将扩展这项工作，以研究这种性别决定途径是否也参与决定雄性形态，以及形态和性别之间的个体差异。我将研究这些操作的影响，以及在行为和大脑方面不同的男性变体之间的差异。大脑的社会行为网络是一组在脊椎动物中高度保守的脑回路。我们可以通过实验诱导这些大脑区域的变化，然后研究对鱼类社会行为的影响，这应该是与人类直接相关的。大脑的性别位于男性和女性极端之间的连续光谱上，这是一个具有非常广泛适用性和相关性的想法。自闭症的许多方面可以被理解为大脑的病理性过度男性化，正如精神病的许多方面可以被理解为大脑的病理性过度女性化。在这两个极端之间存在着一系列连续的认知能力和行为倾向，每一种都有其优缺点。

My lab is focused upon understanding the biological basis of personality-like traits in general, and aggressiveness in particular. We examine the evolution, development and neuroendocrinological mechanisms underlying such individual variation. We aim to understand the evolutionary costs and benefits maintaining variation in behaviour.***Variation in prenatal testosterone exposure during development is thought to permanently organize many behaviours throughout adulthood, particularly those that show sex differences, creating a spectrum of brain sex. Empirical evidence from both human and non-human animals suggests that the strength of sexual differentiation can variably masculinize eventual adult morphology and behaviour alike. Most of this work is purely correlational. Experimental manipulations, such as hormone treatments during development, do not necessarily inform us about the selective pressures on variation if the phenotypes produced are outside the range seen in recent ancestral history.***To create such real-world range variation, I shall experimentally manipulate sex in an ecologically realistic manner by manipulating water chemistry in a species of cichlid fish with environmental sex determination. The intent is to create variation in the degree of mascuilinization of individuals. Lower pH during the first 30 days produces more males in adulthood, and more of those males are of the more aggressive, haremic-tending morph, and fewer are of the monogamy-tending morph. ***Work in many other species with environmental sex determination suggests that methylation of the aromatase gene promoter is associated with the environmental factor and a key part of sex determination. My preliminary data suggests that early pH manipulations influence the methylation of CpG sites in the promoter for both the brain and gonadal version of the aromatase genes. I shall extend this work to examine whether this sex determination pathway is also involved in determining male morph, and individual differences within morphs and sexes. I will examine the effects of these manipulations, and differences between alternative male morphs, in terms of both behaviour and brain. The brain's social behaviour network is a set of brain circuits which is highly conserved across vertebrates. We can experimentally induce changes in these brain regions, then study the effects on social behaviour in fish that should be of direct relevance to humans. ***That the sex of the brain lies on a continuous spectrum between a male and female extreme is an idea with very broad applicability and relevance. Many aspects of autism can be understood as a pathological hypermasculinization of the brain, as many aspects of psychosis can be understood as a pathological hyperfeminization of the brain. Between these extremes lies a continuous range of cognitive abilities and behavioural tendencies, each one with it's strengths and weaknesses.