His research focuses on mechanisms underlying the means by which flowering plant genomes and phenotypes diversify, with a special focus on the phenomenon of genome doubling, or polyploidy. Most of his ~270 publications focus on the cotton genus (Gossypium), in which two diploid and two polyploid species were each independently domesticated thousands of years ago. This nature evolutionary and early human history provide a model framework for exploring the comparative basis of domestication, the origin of form and of diversity in nature, and the evolutionary consequences of genome doubling.