Research Planning Grant: Hormones and Variation in Aggression

类固醇激素在性别行为差异的形成过程中扮演着关键角色，这一过程被称为性别分化。在许多脊椎动物中，激素调节的差异之一是雄性往往比雌性更具攻击性。很少出现在一起的特征，但在Scelopus蜥蜴中发现，使它们成为综合研究荷尔蒙调节攻击差异的理想模型：它们是一组密切相关的物种，(1)攻击水平的雄性和雌性差异可靠；(2)具有明确的攻击行为；(3)在实验室和自由生活条件下都服从激素操作，以及围产期和成年激素操作，以及(4)可以在实验室饲养到成年，并将展示包括攻击在内的所有典型成人行为。休斯博士将研究三种Scelopus物种在用于发出领土攻击信号的形态颜色特征以及雄性和雌性攻击水平差异程度上存在显著差异的神经内分泌基础。这项研究计划拨款将使休斯博士能够(1)使用成熟的测试范式，确定三个研究物种中自由生活的男性和女性的攻击性水平，(2)开发测试三个物种的攻击性的实验室范式，(3)获取繁殖季节的血液样本，用于放射免疫分析，以评估血浆激素水平(未来植入物以生理方式操纵激素水平的实验所需的数据)，以及(4)确定提供最大生理水平所需的激素植入物的大小。

Steroid hormones play key roles in the development of gender differences in behavior, part of the process known as sexual differentiation. In many vertebrates, one such hormone-mediated difference is that males often are more aggressive than females. Features that rarely occur in combination, but are found in Sceloporus lizards, make them an ideal model for the integrative study of variation in hormonal mediation of aggression: They are a set of closely related species that (1) vary reliably in male-female differences in levels of aggression; (2) have unambiguous aggressive behaviors; (3) are amenable to hormone manipulations both in the laboratory and under free-living conditions, and to both perinatal and adult hormone manipulations, and (4) can be reared to adulthood in the laboratory and will exhibit the full array of typical adult behavior, including aggression. Dr. Hews will examine the neuroendocrine basis of dramatic differences among three Sceloporus species in the morphological color traits used in signaling territorial aggression and in the degree to which males and females differ in levels of aggression. This Research Planning Grant will enable Dr. Hews to (1) establish levels of aggression in free-living males and females of the three study species, using a well-established testing paradigm, (2) develop a laboratory paradigm for testing aggression in the three species, (3) obtain breeding-season blood samples for radioimmunoassay to assess plasma hormone levels (data needed for future experiments in which implants manipulate hormone level in a physiological manner), and (4) determine the size of a hormone implant needed to deliver a maximum physiological level.