Dissertation Research: Eggs in one basket: Male mate choice and female mortality risk in a sperm-limited spider

动物在选择配偶时是否会考虑伴侣的死亡风险？在金球蜘蛛Nephila clavipes中，雄性在其一生中可以使用的精子数量有限，因此必须明智地分配精子。它们通常选择与未交配的雌性交配，因为第一个与处女交配的雄性使其大部分卵受精。然而，一个处女雌性储存精子并延迟卵子受精长达一个月，这使得她有可能在产卵前死亡。如果雌性死亡，那么雄性就把有限的精子浪费在了雌性身上。有些雄性不与处女交配，而是在雌性下蛋之前与之前交配过的雌性交配。这项研究表明，这些雄性在减少父权的同时，增加了其配偶存活下来产卵的机会，并使其中一部分卵子受精。在很多情况下，配偶死亡风险可能是选择配偶的一个因素，因为繁殖的回报不是立竿见影的。例如，在有父亲照顾的物种中，雌性被认为会选择条件良好的伴侣，因为它们能提供更多的资源，但这项研究提出了一个不同的原因：父母死亡率较低，将减少后代被遗弃。本项目采用建模、分子和实验方法来评估这一假设。研究人员将测量雄性选择配偶的结果，以及这些结果在繁殖季节如何变化。本项目将提供具有野外观测方法、自然实验、遗传分析和动态建模研究经验的本科生助理。此外，这项研究将有助于校园自然保护区保护项目。了解生殖行为的复杂性对保护工作和维持生物多样性至关重要。

Do animals consider their partner's mortality risk when choosing a mate? In the golden orb spider, Nephila clavipes, males are limited in the amount of sperm they can use over their lifetime and therefore must allocate sperm judiciously. They usually choose to mate with unmated females because the first male to mate with a virgin female fertilizes the majority of her eggs. However, a virgin female stores sperm and delays egg fertilization for up to a month, making it possible that she will die before she lays her eggs. If she dies then the male has wasted his limited sperm on this female. Rather than mate with a virgin, some males mate with a previously mated female just before she lays her eggs. This study proposes that these males are trading off reduced paternity for an increase in the chance that his mate will survive to lay eggs, a portion of which he has fertilized. Mate mortality risk could be a factor in mate choice under a variety of circumstances where reproductive pay-off is not immediate. For example, in species with paternal care, females are thought to choose mates that are in good condition because they provide more resources, but this study suggests a different reason: lower parental mortality rates that will reduce offspring abandonment. This project uses modeling, molecular and experimental approaches to evaluate this hypothesis. The investigators will measure the consequences of mating choices by males and how these consequences change over the breeding season. The project will provide undergraduate assistants with research experience in observational field methods, natural experiments, genetic analysis, and dynamic modeling. In addition, the study will contribute to the campus natural areas conservation project. Understanding the complexity of reproductive behavior is critical for conservation efforts and for maintaining biodiversity.