Reproductive Tactics in an Androdioecious Crustacean - Laboratory and Field Tests of a Model for the Maintenance of a Mixed Mating System

几十年来，异型杂交的有性生殖一直引起进化生物学家的兴趣，因为能够通过自体受精或无性繁殖产生后代的个体比异型杂交具有直接的优势。混合交配系统（包括自体受精和异型杂交）提供了一种很好的方法来识别两种繁殖方式的选择优势。混合交配的一种形式，即雌雄同体（雄性雌雄同体），特别有趣，因为理论治疗表明这种混合在进化上应该是不稳定的。最近发现的一种甲壳类动物（Eulimnadia texana）表现出持久的雄性雌花异株。在之前的一笔资助中，我们采用了一种综合方法来研究雌雄异体，利用遗传、细胞、生理、行为和生态研究来量化两个群体的模型参数。尽管这些项目被证明非常富有成效，但仍然存在许多问题。当前的提案将通过两个综合项目来解决这些问题。 (a) 结合行为和遗传学研究的实验室测试将用于进一步探索模型的两个参数。 (b) 实地收集，估计雄性与雌雄同体的相对存活率、近交衰退和雄性交配成功率，以估计自然栖息地模型的四个参数中的三个。将在新墨西哥州的乔纳达 LTER 站点收集两组现场数据（来自自然填充池塘的数据和来自人工填充池塘的数据）。 从现场和实验室研究收集的数据将用于估计四个模型参数，这反过来又将用于测试模型预测每个池塘中性别类型比例的能力。这些测试的结果将为该系统中异交的维持提供彻底的综合理解，这将进一步加深我们对交配系统进化的总体理解。更广泛的影响：两位 PI 都坚定地致力于学生培训，并致力于为阿克伦地区的高中生和本科生带来基于探究的科学体验。拟议的研究将指导研究生和本科生，他们将获得现代遗传技术的培训，并通过现场经验丰富。

Outcrossing sexual reproduction has intrigued evolutionary biologists for decades, for the individual that can produce offspring by self-fertilization or asexually has an immediate advantage over outcrossers. Mixed mating systems (with both self-fertilization and outcrossing) provide an excellent way to identify the selective advantage of both modes of reproduction. One form of mixed mating, androdioecy (males + hermaphrodites), is particularly interesting because theoretical treatments suggest such a mixture should be evolutionarily unstable. A recently discovered crustacean (Eulimnadia texana) exhibits a persistent form of androdioecy. In a previous grant, we implemented an integrative approach to the study of androdioecy, using genetic, cellular, physiological, behavioral, and ecological studies to quantify the parameters of a model in two populations. Although these projects proved quite fruitful, many questions remain. The current proposal will address those questions with two integrated projects. (a) Laboratory tests that combine behavioral and genetic studies will be used to further explore two of the model's parameters. (b) Field Collections, that estimate relative male to hermaphrodite survival, inbreeding depression and male mating success to estimate three of the four parameters of a model in natural habitats. Two sets of field data will be collected (data from naturally-filled ponds and from artificially-filled) at the Jornada LTER site in New Mexico. Data collected from both the field and laboratory studies will be used to estimate the four model parameters, which will in turn be used to test the ability of the model to predict the proportions of sex types found in each pond. The results of these tests will provide a thoroughly integrative understanding of the maintenance of outcrossing in this system, which will further our understanding of mating system evolution in general. Broader Impacts: Both PIs have strong commitments to student training and are on projects designed to bring inquiry-based science experiences to high school and undergraduate students in the Akron area. The proposed research will mentor graduate and undergraduate students who will gain training in modern genetic techniques, and be enriched by field experiences.