Evolutionary Rewiring of a Developmental Gene Regulatory Network

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This project examines how changes in gene regulation contribute to modifications in key life history traits, such as fecundity, lifespan, and age-specific mortality. Knowing more about how life history traits vary within populations, and how they change over evolutionary time will elucidate fundamental biological processes. The approach involves a detailed analysis of gene interactions during key stages of the life cycle in three species of sea urchins. The experiments involve manipulating the operation of key regulatory genes with known functions during the early phase of the life cycle. The impact of these experimental manipulations will then be assayed using several 'big data' approaches that measure the expression of tens of thousands of genes and thousands of proteins and metabolites during subsequent stages of the life history. These results will reveal how differences in the function of key genes impact the function of other genes, thereby influencing anatomy and health. The broader impacts from this project fall into four areas. First, the novel computational methods for analysis of the very large gene expression datasets will have broad utility for basic and applied research. Second, the large datasets will be made freely available to other researchers who work with the same species. Third, there will be significant contributions to the training young scientists, including undergraduate and graduate students. Finally, this project will extend an innovative educational outreach program to middle school students developed by the PI in partnership with the North Carolina Museum of Science.The objective of this project is to identify evolutionary changes in a well defined gene regulatory network (GRN) that contribute to an ecologically significant shift in developmental mode from planktotrophic (feeding) to lecithotrophic (nonfeeding) larvae in sea urchins. The project is identifing maternal changes underlying GRN activation and egg provisioning, and identify zygotic changes in GRN sub-circuits and assess their impact on larval traits. Changes in the energy content of eggs are essential for the evolution of lecithotrophy. The eggs of H. erythrogramma are larger than those of H. tuberculata and other planktotrophs and are packed with prominent lipid droplets. Interestingly, the amount of vitellogenin (yolk protein) per egg is not elevated, but triglycerides and long chain fatty acids are vastly more abundant. Thus, this project focuses on changes in lipid metabolism that may have contributed to the evolution of lecithotrophy in H. erythrogramma to identify specific metabolites that support lecithotrophic development and to understand how those changes might have evolved.