Life-history Trade-offs and the Evolution of Multicellularity

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The major landmarks in the diversification of life and the hierarchical organization of the living world are consequences of a series of transitions in individuality, whereby groups of previously independent individuals become so integrated that a new kind of individual emerges. Such events include, for instance, the origin of the first cell, the evolution of multicellular organisms, and the evolution of societies. How and why do groups evolve into individuals? These are the central questions motivating our work. The evolution of multicellular organisms is the premier example of the integration of lower level individuals (cells) into a new, higher-level individual in which cells co-operate and specialize (i.e., division of labor) at functions related to survival (sterile somatic cells) or reproduction (germ cells). Using the volvocine green algae as an experimental model-system, this project studies how somatic cells evolved by examing the genetic basis for these traits. The processes responsible for that evolution will be examined through tests of the hypothesis that the cost of reproduction increases with body size, with this increasing cost selecting for increasing cellular specialization for functions affecting either reproduction or survival.This project is part of a larger initiative to develop the volvocine green algae as a model system to study complexity, much as other organisms serve the studies of genetics and development. This initiative includes the Volvocales Research and Education Center that will develop study plans and instructional materials for high schools to facilitate the study of complexity using Darwin's principles and the volvocine green algae as a model-system.