Donald A. Levin is a professor of integrative biology at the University of Texas at Austin. He received his Ph.D. at the University of Illinois in 1964 and served on the faculties of the University of Illinois and Yale University before moving to Texas. His research focuses on evolutionary processes in plants including hybridization. Levin’s interest in the connection between hybridization and extinction was piqued by Javier Francisco-Ortega of Florida International University in Miami, an expert in floral hybridization on the Canary Islands. Address: Section of Integrative Biology, University of Texas, Austin, TX 78713. Internet: dlevin@uts.cc.utexas.edu