DISSERTATION RESEARCH: Experimental Test of Sex Allocation Theory Using the Protandric Simultaneous Hermaphrodite Lysmata wurdemanni (Crustacea: Decapoda) as a Model System

原始同时两性畸形（英语：Protandric simultaneous hermaphroditism，PSH）是一种新的海虾性系统，指的是海虾首先以雄性繁殖，然后在以后的生活中以同时两性体繁殖。PSH被认为是一种“混合”性系统，因为具有该系统的物种具有严格顺序雌雄同体的特征（即，其中个体首先以一种性别繁殖然后以相反的性别繁殖）和严格的同时雌雄同体（即，其中个体在其一生中既作为雄性又作为雌性繁殖）。最近，已经提出了各种理论模型来解释这种“混合”性系统的进化。在这项研究中，这些模型将进行测试，第一次使用作为模式物种的虾Lysmatawurdemanni。此外，这项研究将探讨是否社会环境（即，种群中不同性变体的个体的数量和相对丰度）影响虾投入雄性和雌性生殖的时间/资源的比例（即，性别分配）。假设这种“社会中介的性别分配”预测严格顺序和严格同时雌雄同体将进行测试。智力优势：分配给男性和女性生殖在这PSH虾的资源/时间的比例可能会改变根据制定严格顺序和严格同时雌雄同体的预测。如果是这样的话，这将表明严格顺序雌雄同体、严格同时雌雄同体和PSH是从进化的角度来看的“单一主题的变体”。性别分配理论可能需要一个单一的综合模型来预测顺序两性畸形、同时两性畸形、PSH和雌雄异株的进化。这种模式将提出在本研究的基础上，从实验的成本和效益的研究虾的性功能的信息。更广泛的影响：本提案的资助将加强共同主要研究者的博士培训和专业发展。此外，本研究还考虑了本科生的培训。通过与研究生的互动，激发本科生对科学的兴趣，帮助他们启动科学载体。 PI在教育研究生和本科生方面有着良好的记录。

Protandric simultaneous hermaphroditism (PSH), in which individuals first reproduce as males and then later in life as simultaneous hermaphrodites, is a novel sexual system described for marine shrimps (genus Lysmata). PSH is considered a 'mixed' sexual system because species featuring it have characteristics of both strict sequential hermaphrodites (i.e., in which individuals reproduce as one sex first and then later life as the opposite) and strict simultaneous hermaphrodites (i.e., in which individuals reproduce as both male and female throughout their life). Recently, various theoretical models explaining the evolution of this 'mixed' sexual system have been proposed. In this study, these models will be tested for the first time using the shrimp Lysmata wurdemanni as a model species. In addition, this study will explore whether or not the social environment (i.e., the number and relative abundance of individuals of the different sexual morphs in a population) affects the proportion of time/resources invested into male and female reproduction by shrimps (i.e., sex allocation). Hypotheses on this 'social mediation of sex allocation' as predicted for strict sequential and strict simultaneous hermaphrodites will be tested. Intellectual Merit: The proportion of resources/time allocated to male and female reproduction in this PSH shrimp may shift according to predictions formulated for both strictly sequential and strictly simultaneous hermaphrodites. If so, this would suggest that strictly sequential hermaphroditism, strict simultaneous hermaphroditism, and PSH are "variations of a single theme" from an evolutionary perspective. Sex allocation theory may be in need of a single comprehensive model predicting the evolution of sequential hermaphroditism, simultaneous hermaphroditism, PSH, and gonochorism, all together. Such a model will be proposed in the present study based on information from experiments on the costs and benefits of the sexual functions in the studied shrimp. Broader impact: Funding of this proposal will enhance the Co-PI's doctoral training and professional development. In addition, this study contemplates the training of undergraduate students. This training and the interaction with graduate students are expected to stimulate the interest of undergraduates in science, and help them to launch their scientific carriers. The PI has a strong record of educating graduate and undergraduate students.