Polyandry: Proximate Mechanisms and Ultimate Causes

一妻多夫制：直接机制和最终原因

• 批准号: 0115986
• 负责人: Jeanne Zeh
• 金额: $ 34.45万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0115986&HistoricalAwards=false
• 关键词: Polyandry; Proximate; Mechanisms; Ultimate; Causes

IBN-0115986, Lay AbstractThe revolution that has taken place in molecular biology over the past decade has revealed one of nature's best kept secrets, namely, that females across a wide range of animal species commonly mate with more than one male. Identifying the causes and consequences of such polyandrous behavior is of general significance to a broad spectrum of biological disciplines, ranging from developmental and conservation genetics to the study of new species formation. Unfortunately, however, the technical difficulties associated with evaluating the alternative material and genetic benefit hypotheses that have been proposed to explain polyandry make investigation of this behavior largely intractable in many species. The development of powerful, polymerase chain reaction (PCR) techniques for assigning paternity, in combination with a unique suite of reproductive and behavioral characteristics, make the pseudoscorpion, Cordylochernes scorpioides, a model invertebrate organism for experimental investigation of the selective forces favoring polyandry. Accurate assessment of female sexual receptivity in these pseudoscorpions is greatly facilitated by their indirect method of sperm transfer via a spermatophore deposited on the substrate. Female reproductive status and embryonic development can be readily monitored without the need for invasive techniques, due to Cordylochernes scorpioides' "external womb" form of viviparity (live birth), in which females nourish embryos in an external, translucent brood sac overlying the genital aperture. In addition, these pseudoscorpions produce large broods, have a rapid generation time, and are highly amenable to large-scale, laboratory behavioral, rearing and genetic studies of individuals derived directly from natural populations.Previous research has established that polyandry in Cordylochernes scorpioides significantly enhances female lifetime reproductive success, and that it is an active strategy in which females recognize and reject previous mates. Over their lifetime, females mated to two different males gave birth to 32% more offspring than did females mated twice to the same male. This was primarily as a consequence of a significantly reduced rate of spontaneous abortion, strongly suggesting that polyandry reduces the risk and/or cost of fertilization by genetically incompatible sperm. The goal of the proposed research is to gain a better understanding of the behavioral and physiological mechanisms underlying polyandry in Cordylochernes scorpioides. A combination of behavioral experiments and molecular techniques will be used to address the following questions:1. What is the recognition mechanism used by females to discriminate against previous mates and preferentially accept sperm from novel males in order to access the reproductive benefits of polyandry? 2. To what extent is the enhanced lifetime reproductive success of polyandrous Cordylochernes scorpioides females due to 'cryptic material benefits' deriving from a rescuing effect of multi-male seminal fluid products, as opposed to post-mating mechanisms that bias paternity in favor of more compatible or genetically superior males?3. To what extent do processes acting prior to fertilization (sperm competition and/or female choice of sperm) versus processes acting after fertilization has occurred (reallocation of maternal resources from defective/inferior embryos to viable/superior embryos during gestation) contribute to paternity biasing in polyandrous females? As the first study to investigate the relative importance of pre- versus post-fertilization paternity-biasing mechanisms in a live-bearing species, the findings of this research should contribute to a better understanding of the role that reproductive mode may play in the evolution of female mating behavior.

在过去的十年里，分子生物学领域发生的革命揭示了自然界保守得最好的秘密之一，即在许多动物物种中，雌性通常与一个以上的雄性交配。确定这种一妻多夫行为的原因和后果对广泛的生物学学科具有普遍意义，从发育和保护遗传学到新物种形成的研究。然而，不幸的是，与评估替代物质和遗传利益假说相关的技术困难已经被提出来解释一妻多夫制，这使得在许多物种中对这种行为的调查在很大程度上难以进行。强大的聚合酶链反应（PCR）鉴定技术的发展，加上一套独特的生殖和行为特征，使假蝎子Cordylochernes scorpioides成为一种无脊椎生物的模型，用于实验研究偏向多夫制的选择力。这些假蝎子通过沉积在基质上的精子包囊来间接转移精子，这极大地促进了对雌性性接受性的准确评估。由于Cordylochernes scorpioides的“外子宫”胎生（活产）形式，雌性在生殖孔上方的外部半透明育卵囊中滋养胚胎，因此无需侵入性技术即可轻松监测雌性生殖状态和胚胎发育。此外，这些假蝎子产生大量的后代，具有快速的一代时间，并且非常适合直接从自然种群中获得的个体进行大规模的实验室行为，饲养和遗传研究。先前的研究已经证实，Cordylochernes scorpioides的一妻多夫制显著提高了雌性一生的生殖成功率，这是一种主动的策略，雌性可以识别和拒绝以前的配偶。在它们的一生中，与两个不同的雄性交配的雌性比与同一个雄性交配两次的雌性多生出32%的后代。这主要是由于自然流产率显著降低的结果，强烈表明一妻多夫制降低了基因不相容的精子受精的风险和/或成本。本研究的目的是为了更好地了解Cordylochernes scorpioides多夫制的行为和生理机制。行为实验和分子技术的结合将用于解决以下问题：1。为了获得一妻多夫制的生殖优势，女性歧视以前的配偶并优先接受新男性的精子的识别机制是什么？2. 在多大程度上，一妻多夫的Cordylochernes scorpioides雌性的终生生殖成功率提高是由于多雄精液产品的拯救作用所产生的“隐性物质利益”，而不是交配后的机制，即偏向父权倾向于更兼容或基因更优越的雄性？受精前的过程（精子竞争和/或女性选择精子）与受精后的过程（妊娠期间母体资源从缺陷/劣质胚胎重新分配到有活力/优质胚胎）在多大程度上导致了多夫制女性的父权偏倚？作为第一个研究受精前和受精后父权偏向机制在活育物种中的相对重要性的研究，本研究的发现将有助于更好地理解生殖模式在雌性交配行为进化中可能发挥的作用。