It is a long-held view in biology that males can enhance their reproductive success through multiple partners whereas females cannot. Yet, females of many species mate multiply. Many explanations exist including the possibility that females do not benefit (polyandry results from male competition); or, alternatively, that females benefit either from resources that males provide or through improved mate quality or greater genetic compatibility. This study evaluates these hypotheses in the horseshoe crab, a species in which males provide only paternity. Horseshoe crabs spawn in pairs with some females attracting additional satellite males that may fertilize many eggs. This study measures the success of multiply and singly mated females in both the field and laboratory. Experiments examine the effect of multiple paternity on female egg-laying success, egg development and larval survivorship and viability. As an ancient and independently evolved arthropod, horseshoe crabs offer a unique opportunity to extend our understanding of the evolution of reproductive behavior. This project has many broader impacts. First, the harvest of horseshoe crabs as bait and for use in the biomedical industry is managed because horseshoe crab eggs are an important food for shorebirds. This study provides crucial data that are being used in the management of this controversial species. Second, horseshoe crabs are at the center of a successful curriculum to teach middle and high school students about science, management and conservation and the PI and her students participate in this effort. Third, the results of this study are disseminated to a public web site and international forum on the biology and conservation of horseshoe crabs. Finally, the project provides many opportunities for students at all levels to learn how to conduct research in field and laboratory settings on the behavior of a fascinating marine invertebrate.
