Reproductive Biology in Shrimp

一种海虾，Lysmata wurdemanni，在十足甲壳类动物（虾、蟹、龙虾）中具有独特的生殖系统。就像原始虾一样，大多数个体首先是雄性，然后当它们变大变老时变成雌性。然而，与其他性别改变者不同的是，在雌性阶段，产生雄性配子和作为雄性受精的能力被保留下来，也就是说，“雌性”同时是雌雄同体。这是一个独特的系统，用于测试解释序列两性现象的近似和最终因素的假设，不仅在Lysmata虾，而且在其他原雄性虾中。一组目标是确定为什么，从生殖成本和收益的角度来看，一个人会改变性别，为什么男性的生殖功能保留在女性阶段。在这个物种中，这种成本和收益可以在同一个体中进行测量和比较。该项目的另一个重要目标是确定性别变化是否受环境控制，即是否受个人所处的人口和社会结构的影响。对鱼类序贯性雌雄同体的研究揭示了其控制和进化的相关因素。在十足类虾中，很少有关于雌雄同体的理论测试。利用Lysmata wurdemanni作为模型系统，提出的研究将在测试虾的环境性别决定问题和Lysmata属不寻常的雌雄同体系统的进化方面迈出关键的第一步。这项研究将有助于解释顺序和同时雌雄同体是如何以及为什么在一些十足甲壳类动物中进化的，而在许多其他密切相关的分类群中却没有。

A marine shrimp, Lysmata wurdemanni, has a unique reproductive system among decapod crustaceans (shrimps, crabs, lobsters). As in protandric shrimps, most individuals function first as a male and then change to female when they are larger and older. However, unlike other gender-changers, the capacity to produce male gametes and fertilize as a male is retained during the female -phase, i.e., the "females" are simultaneous hermaphrodites. This is a unique system in which to test hypotheses on the proximate and ultimate factors explaining sequential hermaphroditism, not only in Lysmata spp. but also in other protandric shrimps. One set of objectives is to determine why, in terms of reproductive costs and benefits, an individual makes the gender change and why male reproductive function is retained in the female phase. With this species, such costs and benefits can be measured and compared within the same individual. The other important goal of the project is to determine if gender change is environmentally controlled, i.e., mediated by the population and social structure in which an individual occurs.Research on sequential hermaphroditism in fishes has revealed much about the factors involved in its control and evolution. In decapod shrimps, there has been little testing of theory about hermaphroditism. Using Lysmata wurdemanni as a model system, the proposed research will take a crucial first step in testing questions on environmental gender determination in shrimps and on the evolution of unusual hermaphroditic systems in the genus Lysmata. The research will contribute to an explanation of how and why sequential and simultaneous hermaphroditism have evolved in some decapod crustaceans but not in many other closely-related taxa.