ABSTRACT
In Chapter 9, several critical events that allowed eukaryotic cells to form multicellular organisms are considered. Specifically, the role sexual reproduction may have played in generating multicellular eukaryotes is explored, and the molecular processes that generate sex-based genetic diversity are addressed. The benefits a colony of sexually reproducing cells gain by sharing the same genes are also contemplated, and the selective pressures that led to the formation of colonies of genetically identical cells are reviewed. Once genetically identical, sexually reproducing cells existed, differential gene expression within these populations lead to cellular specialization. Examples of the ways in which this process benefited multicellular organisms are presented. At the end of this chapter, the conditions that led to the evolution of multicellular animals are contemplated. In addition, the circumstances that led to the radiation and diversification of animals during the Cambrian era are explored.
