Michael T. Clegg received his B.S. in agricultural genetics and Ph.D. in genetics at the University of California, Davis. In 1972, he joined the faculty of Brown University, moving to the University of Georgia in 1976. In 1984, he assumed the position of professor of genetics at the University of California. He also served as dean of the College of Natural and Agricultural Sciences from 1994 to 2000 and he was the founding director of the Genomics Institute, now renamed the UCR Institute for Integrative Genome Biology. In July 2004, he joined the faculty of UC Irvine.

During an academic career of over 30 years, Clegg has published approximately 150 research articles and book chapters and he has authored or edited seven books. Clegg's research specialty is population genetics and molecular evolution. His early work in population genetics focused on the dynamical behavior of linked systems of genes in plant and Drosophila populations. During this period, he also contributed to the theoretical study of multilocus systems employing computer simulations together with the analysis of mathematical models. Later he helped pioneer the comparative analysis of chloroplast DNA variation as a tool for the reconstruction of plant phylogenies. His current work is concerned with the comparative genomics of plant gene families, the molecular evolution of genes in the flavonoid biosynthetic pathway, the use of coalescent models to study crop plant domestication and the application of molecular markers to avocado improvement.

Clegg has received numerous awards including a Guggenheim Fellowship (1981) and the Darwin Prize of Edinburgh University (1995). Clegg was elected to membership in the U.S. National Academy of Sciences in 1990 and he was elected a fellow of the American Academy of Arts and Sciences in 1992. He was elected foreign secretary of the U.S. National Academy of Sciences in 2002, and served as president of the American Genetic Association (1987), president of the International Society for Molecular Biology & Evolution (2002) and chair of the Section on Agriculture, Food and Natural Resources of the American Association for the Advancement of Science (2003).