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

我的实验室致力于从总体上理解类个性特征的生物学基础，尤其是攻击性。我们研究了这种个体差异背后的进化、发育和神经内分泌机制。我们的目标是了解维持行为变异的进化成本和收益。 发育过程中孕期睾丸激素暴露的变化被认为会在整个成年期永久性地组织许多行为，特别是那些表现出性别差异的行为，创造了一系列脑性行为。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类似地男性化。这些工作中的大部分纯粹是相互关联的。如果产生的表型超出了近代史上看到的范围，那么实验操作，如发育过程中的激素治疗，不一定会告诉我们对变异的选择压力。 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，通过操纵一种具有环境性别决定的池鱼物种的水化学。其目的是在个体的咀嚼程度上创造差异。在最初的30天内，较低的PH值会产生更多的成年雄性，其中更多的雄性是更具攻击性的、有血缘倾向的类型，而更少的是一夫一妻制的类型。 在许多其他物种的环境性别决定中的工作表明，芳香酶基因启动子的甲基化与环境因素有关，也是性别决定的关键部分。我的初步数据表明，早期的pH控制会影响大脑和性腺版本芳香酶基因启动子中CpG位点的甲基化。我将扩展这项工作，以研究性别决定途径是否也参与决定男性的形态，以及形态和性别之间的个体差异。我将研究这些手法的效果，以及不同的男性变形在行为和大脑方面的差异。大脑的社会行为网络是一套在脊椎动物中高度保守的大脑回路。我们可以在实验中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，这些行为应该与人类直接相关。 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的适用性和相关性的想法。自闭症的许多方面可以理解为大脑的病理性男性化，就像精神病的许多方面可以理解为大脑的病理性超男性化一样。在这两个极端之间存在着一系列持续不断的认知能力和行为倾向，每一种都有自己的长处和短处。

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.