Contemporary co-evolution of gamete recognition proteins

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This project examines variation over time in the interacting sperm and egg recognition proteins in a species of sea urchin that has experienced a profound shift in population density over the past 200 years. The proteins on the surface of eggs and sperm determine which males can reproduce with which females and often define whether one species is distinct from another. This study will determine what makes fertilization possible among some individuals but not others. It combines two disciplines to understand how ecological processes (when are novel proteins more successful?) can drive evolution (when do new proteins proliferate in the genome?). Insight will be gained into how populations might rapidly evolve reproductive traits to adapt to rapid changes in the abundance of species. It will also provide data on how reproductive behavior can influence the association between interacting genes. Students, particularly those from underrepresented groups, will be trained in molecular biology and field ecology. Understanding the evolution of reproductive compatibility may help in the management of small populations and captive breeding for species of conservation interest.Theory predicts that gamete recognition might be relaxed when population density is low and gamete competition is relaxed. Fertilization experiments will examine how specific sperm and egg proteins interact to determine reproductive compatibility and how patterns of sperm availability influence selection on these proteins. Sea urchins provide a model system for exploring these questions that would be impossible in species, such as mammals, with internal fertilization. The ability to age sea urchins, which can live for over 200 years, coupled with long-term data on human-driven changes in sea otter population density enables this unique historical study of evolution in action. This research will provide key insights into why some males and females have increased reproductive compatibility and why selection often favors the evolution of incompatible types.