Project: Reproductive pairing, conflict and offspring size in a marine snail.

All organisms face two allocation trade-offs: one between many small versus a few large offspring; and the second between present and future reproduction. Nowhere are these allocation trade-offs more apparent than in the vast range of variation in egg, offspring, and clutch size exhibited among species of marine invertebrates. It has become increasingly clear that, in many taxa of marine and terrestrial organisms, there is substantial intraspecific variation for egg and hatching size. This project focuses on a rarely considered, but potentially widespread, source of variation in egg and offspring size, namely, the inevitable conflicts of interest that arise over the optimal distribution of parental resources among siblings. The reproductive pairing system - because of its effects on the relatedness of interacting siblings - can have a decisive impact on the magnitude and resolution of these conflicts. This research characterizes how variation in the pairing system of a marine snail (Nucella ostrina) accounts for variation in maternal provisioning and offspring size. The work will also establish whether shifts in the reproductive pairing system correspond to patterns and modes of maternal provisioning across the entire genus of Nucella.

This project has several broad scientific implications: 1) Polyandry and encapsulation of offspring are widespread in marine organisms, angiosperms, and matrotrophic animals; however, few studies have considered their evolutionary ramifications, especially their costs. 2) Reproductive pairing system and parental-offspring conflict may also drive the evolution of post-zygotic reproductive isolation. This research brings to light a novel and potentially widespread mechanism causing such isolation in marine systems. 3) This study examines consequence of the links between oceanographic processes that affect recruitment of prey species, such as barnacles and mussels, and their predators. Unlike other well-studied predators such as seastars, Nucella has limited dispersal potential, hence is far more likely to exhibit spatially constrained population dynamics as well as adaptations that reflect varying food supplies. 4) The research will advance our understanding of the scale of ecological and evolutionary connections among members of marine communities, providing the foundation for scientifically informed design of marine reserve networks that sustain both species and genetic diversity. The snail, Nucella, has similarities to marine animal predators on commercially important marine resource species.