Daniel L. Hartl is a Professor of Biology in the Department of Organismic and Evolutionary Biology at Harvard University. He received his Ph.D. in Genetics from the University of Wisconsin-Madison, with James F. Crow, then did postdoctoral work with Spencer W. Brown at the University of California-Berkeley. Prior to taking on his current role at Harvard in 1993, Dr. Hartl held teaching positions at the University of Minnesota-St. Paul, Purdue University, the University of Zurich, and the Washington University School of Medicine. In addition to Principles of Population Genetics, Third Edition (written with Andrew G. Clark), he has authored or co-authored several other genetics books. Dr. Hartl served as President of the Genetics Society of America in 1989. His research interests include population genetics, molecular evolutionary genetics, and molecular genetics.