Polyandry and Male Variability in a Heterogeneous Environment

异质环境中的一妻多夫制和男性变异性

• 批准号: 9514245
• 负责人: David Zeh
• 金额: $ 8.63万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-04-01 至 1999-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9514245&HistoricalAwards=false
• 关键词: Polyandry; Male; Variability; Heterogeneous; Environment

Abstract Zeh 9514245 Theoretical models generally portray sexual selection as a constant, undirectional force, driving a population towards a single, optimal male phenotype. Species are assumed to occupy homogeneous environments and to experience selection either through male competition or through mate choice by monogamous females. This view fails to explain why sexually-selected male characters are often precisely those which exhibit the greatest variability, perhaps because the models do not reflect the complexity of factors influencing trait evolution in nature. Many species, particularly those that exploit ephemeral resources, are subject to fluctuating environmental conditions. In addition, DNA fingerprinting has revealed that multiple paternity, and hence polyandry, is far more common than previously assumed. The research proposed here will test the hypothesis that sperm storage by polyandrous females, superimposed on male competition in a heterogeneous environment, can contribute to the maintenance of variability in male sexually-selected characters by carrying genotypes through episodes of unfavorable selection. The development of single-locus minisatellite DNA probes for a species whose natural history and reproductive biology are highly amenable to experimentation makes the neotropical pseudoscorpion, Cordylochernes scorpioides, a model system for testing this hypothesis. As an essential first step in carrying out a rigorous test of the sperm-storing females as carriers of male genetic variability hypothesis, the proposed research will determine whether all the elements of this model are present in the C. scorpioides system. First, to assess whether sexual selection favors a significantly smaller male phenotype within trees than on beetles, DNA fingerprinting will be used to quantify the relationship between male size and reproductive success in experimental tree populations. Second, to assess the ca pacity of females to act as carriers of male variability, DNA fingerprinting will be used to compare levels of multiple paternity in the broods of females captured in the act of boarding and of disembarking from beetles. In addition, sperm utilization patterns will be investigated in a semi-natural experimental simulation of a dispersal episode. Finally, to assess the potential for exaggerated male traits to respond to selection in the two environments, the design of the within-tree sexual selection experiment will provide field estimates of heritability based on paternity assignment and son/sire regression involving field-caught males (sires)and their male offspring recaptured after release and development to maturity in the field. Assuming that all the elements necessary for the model are found to exist in this pseudoscorpion system, the development of quantitative simulation models to investigate how selection in the two environments may be balanced will be the focus of future research.

摘要 Zeh 9514245 理论模型通常把性选择描绘成一种恒定的、无方向的 力，驱使一个群体走向单一的，最佳的男性表型。 物种被假定为占据同质环境，并通过男性竞争或通过一夫一妻制女性的配偶选择经验的选择。 这种观点无法解释为什么性选择的男性角色往往恰恰是那些表现出最大变异性的角色，也许是因为模型没有反映出影响自然界特征进化的因素的复杂性。 许多物种，特别是那些利用短暂资源的物种，受到波动的环境条件的影响。 此外，DNA指纹分析显示，多个父亲，因此一妻多夫制，远比以前假设的更为普遍。 这里提出的研究将测试的假设，精子存储由一妻多夫制的女性，叠加在男性的竞争在异质环境中，可以有助于维持变异的男性性选择字符进行基因型通过情节不利的选择。 单位点小卫星DNA探针的发展，其自然历史和生殖生物学是非常适合实验的一个物种，使新热带假蝎，Cordylochernes scorpioides，模型系统，用于测试这一假设。 作为对储存精子的雌性作为雄性遗传变异假设的携带者进行严格测试的必要的第一步，拟议的研究将确定该模型的所有元素是否存在于C. Scorpioides系统 首先，为了评估性选择是否有利于一个显着较小的男性表型比甲虫在树木中，DNA指纹将被用来量化男性的大小和繁殖成功的实验树种群之间的关系。 第二，为了评估女性作为男性变异携带者的能力，DNA指纹将被用来比较在登船和下船的行为中捕获的女性的育雏中的多个父系的水平。 此外，精子利用模式将在一个半自然的实验模拟的扩散插曲。 最后，为了评估夸大的男性特征的潜力，以应对选择在两个环境中，树内性选择实验的设计将提供现场估计遗传力的基础上，亲子鉴定分配和儿子/父系回归涉及现场捕获的男性（父系）和他们的男性后代夺回后释放和发展到成熟的领域。 假设该模型所需的所有元素都存在于这个伪蝎系统中，定量模拟模型的发展将是未来研究的重点，以研究在这两种环境中的选择如何平衡。