Conservation of hybrid plants

There is currently considerable debate about the treatment of natural hybrids in conservation legislation. The "hybrid policy" recently advocated by Stephen J. O'Brien and Ernst Mayr (Perspective, 8 Mar. 1991, p. 1187) is to 'discourage hybridization between species." This policy is based on examples of animals in which hybridization is thought not to have played a significant evolutionary role. In contrast, we argue that plant hybrid zones are hot spots of ecological and evolutionary activity and should be conserved.