Dissertation Research: An Examination of Variations on the Theme of Livebearing

水蛭科包括一种产卵的鱼类和大约200种产活的幼鱼。胎生动物包括许多有胎盘的物种，这一特征通常被认为只存在于哺乳动物中。胎盘生殖是一种营养不良（母体喂养），或受精后母体供给。它在生物多样性中进化了多次。尽管它有许多起源，而且作为一种生活史特征显然很重要，但对于是什么塑造了它的进化却没有解释。水蛭科的多样性有助于研究形成不同母体供给模式的因素。建议的研究包括实验室，现场和数据挖掘技术，以检验肥大和生殖分配进化的几个假设。这项工作代表了从萎缩进化的唯一理论模型中得出的预测的第一个实验测试，检验了几个特别的假设，并有可能产生新的，可测试的假设。这将有助于对肌萎缩的进化进行更广泛的研究。它包括与开发该模型的理论家的合作，因此，实证研究可以告知和修改当前的模型，使其在生物学上更现实。众多本科生将参与到这项研究中。

The fish family Poeciliidae includes one species that lays eggs and approximately 200 that bear live young. The livebearers include many species with placentas, a trait commonly thought to exist only in mammals. Placental reproduction is a type of matrotrophy (mother feeding), or post-fertilization maternal provisioning. It has evolved multiple times in a diversity of organisms. Despite its many origins and apparent importance as a life history trait, there is no explanation for what shaped its evolution. The diversity in the Poeciliidae facilitates the study of factors that shape different modes of maternal provisioning. The proposed research includes laboratory, field, and data-mining techniques to examine several hypotheses for the evolution of matrotrophy and reproductive allocation. This work represents the first experimental test of predictions derived from the only theoretical model for the evolution of matrotrophy, examines several ad-hoc hypotheses, and has the potential to generate new, testable, hypotheses. It will facilitate broader studies on the evolution of matrotrophy. It includes collaborations with the theoreticians that developed this model, so that empirical research can inform and modify the current model and make it more biologically realistic. Numerous undergraduates will participate in this research.