Introducing species to a new environment creates excellent conditions for evolution, as the species are released from their old enemies and subjected to new conditions. Our work has shown that 70% of the plant species introduced to Australia have changed the way they grow since arriving here. We investigated one species in detail (the South African Beach Daisy, Arctotheca populifolia; see picture) and found that the changes are so great that the introduced population is developing reproductive isolation from its source population. That is, at least one of our introduced plants appears to be becoming a unique new species. If Australia cannot eradicate introduced species (and it seldom can), then it seems inevitable that many more species will eventually evolve to become unique new taxa. At this point, we will have to decide whether to accept them as new native species or continue trying to control them. While most people do not like the idea yet, I think acceptance of introduced species is just a matter of time. I have been called a witch for these ideas before - bring on the arguments!
