| Abstract: | Concern over alien species has changed over the last century. In Britain before ca. 1950 the main anxiety was with vermin, but whether 'harmful' species were introduced or already native was considered relatively unimportant. Scientists were content to welcome some alien species and occasionally to recommend their encourage ment. In the 1970s and 1980s, however, a backlash followed the greater appreciation of damage to native ecosystems caused by exotics across the world, and a deeper interest in genetics. This unfortunately also led to a concept of 'genetic integrity', and campaigns began against introductions that might interbreed with natives. A more defensible approach might be to revive the notion of some species as pests, but to hesitate before involving conservation in anything analogous to ethnic cleansing for other species. |
