In general, his interests focus on genetic diversity and its role in evolution. This allows an eclectic research program, with papers on viruses, bacteria, fungi, diatoms, green algae, invertebrates, plants, sharks, and mammals in the last five years. Two of his main research programs include the origins and environmental consequences of antibiotic resistance, and the new geological era of the Anthropocene, precipitated by human effects on planetary systems. He teaches a large first year class, with 1100 students, and contributes regularly to radio, television and on-line forums.