DISSERTATION RESEARCH: Hermaphroditic Strategies in the Opisthobranch Gastropod, Aplysia Californica

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Hermaphroditism is widespread in invertebrates, such as freshwater snails, flatworms, and barnacles. Surprisingly little is known about hermaphroditic reproductive strategies. Hermaphroditic species are those in which individuals have both male and female reproductive systems and can mate in either role. The PIs do not understand the strategic tradeoff between investing energy in male versus female roles that allows an individual to reproduce optimally, i.e. produce the most possible offspring over its lifetime. Preliminary studies on sea slugs indicate that body size is an important determinant of mating strategies: large animals tend to function as females more than small animals. This study will develop a mathematical model to predict the best reproductive strategy for sperm-storing hermaphrodites of varying body sizes. Predictions of the model will be tested using a common sea slug, the California Sea Hare (an opisthobranch Gastropod), by observing matings in the field and conducting lab experiments. In addition, DNA based paternity analysis will quantify how many offspring can be sired by mating in the male role given that individuals can mate several times and store the sperm received from several mates before egg-laying.The findings of this project will provide new insights into the understanding of reproductive behavior and physiology, along with shedding light on why hermaphroditism is widespread in invertebrates, and also why nearly all opisthobranch Gastropods, like the California Sea hare, are hermaphrodites.