Consequences of Within Organism Variation

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9527716 MICHOD This project studies the transition in evolution from cells to organisms for the purpose of understanding the emergence of organisms as a new unit of selection. The issues considered are applicable to all major transitions in evolution, such as from individual genes to gene networks, from gene networks to bacteria-like cells, from bacteria-like cells to eukaryotic cells with organelles, from cells to multicellular organisms, and from solitary organisms to societies. All transitions in the units of selection share two common themes: (i) the emergence of cooperation among the lower level units in the functioning of the new higher level unit, and (ii) regulation of conflict among the lower level units. These issues are represented in explicit genetical models of mutation and selection within and between organisms for the purpose of understanding certain general, but by no means universal, features of organisms: the presence of a sequestered germ line, maternal control of cell fate during early development, and the passage of the reproductive cycle through a single cell state-the zygote. The research is applicable to the conflict among cells that arises within organisms in the development of cancers.