Department of Psychology, Cornell University, Ithaca, New York, USA.
Gen Comp Endocrinol. 2012 May 1;176(3):279-85. doi: 10.1016/j.ygcen.2011.12.040. Epub 2012 Jan 10.
Comparative endocrinology is a fascinating field of science in part because it addresses both ultimate and proximate causation. Research on sexual dimorphism and sexual differentiation has excellent potential for this kind of integration. Vertebrate comparative endocrinologists have made many important discoveries about the role of genes and sex steroid hormones in the organization and activation of sexually differentiated behavior, brain function, anatomy and physiology. In addition to taxonomically general principles and conserved features, there is also striking diversity in sexual differentiation processes. Much of the evolutionary basis of this diversity (its phylogenetic history and adaptive functions) is not well understood. A set of questions is raised to illustrate this point, with an emphasis on mechanisms of sexual dimorphism in body size and ornamentation, sexual differentiation of avian behavior, particularly in Japanese quail and zebra finches, and the puzzle of the phylogenetic distribution of vertebrate sex determining mechanisms. Applying a comparative approach grounded in established phylogenies and concepts from evolutionary developmental biology such as developmental modules holds promise for generating and testing new hypotheses and eventually answering some of these questions.
比较内分泌学是一门引人入胜的科学领域，部分原因在于它同时涉及终极和近因因果关系。关于性二态性和性分化的研究具有很好的这种综合潜力。脊椎动物比较内分泌学家在基因和性类固醇激素在组织和激活性别分化行为、大脑功能、解剖和生理学方面的作用方面取得了许多重要发现。除了分类学上的普遍原则和保守特征外，性分化过程也存在惊人的多样性。这种多样性的很大一部分进化基础（其系统发育历史和适应功能）还不是很清楚。提出了一组问题来说明这一点，重点是体型和装饰物的性二态性、鸟类行为的性分化（特别是在日本鹌鹑和斑胸草雀中）以及脊椎动物性别决定机制的系统发育分布之谜的机制。应用基于已建立的系统发育和进化发育生物学概念（如发育模块）的比较方法，有望产生和测试新的假设，并最终回答其中的一些问题。
