Evolutionary potential refers to the ability for a species to maintain sufficient genetic variation to allow it to adapt to changes in its environment. The current and anticipated rapid rate of climate change, coupled with the massive anthropogenic fragmentation of formerly continuous native habitats makes the maintenance of the potential for evolutionary change vital in preventing extinction. We discuss the importance of the maintenance of evolutionary potential in delivering conservation of biodiversity and argue that populations ought to be as much a target for conservation actions as species are, if we are to achieve the objective of arresting extinction.
We assess the extent of the general commitment to the maintenance of evolutionary potential at an international level as well as in Australian legislation and we examine the extent to which this objective is pursued by listing threatened populations for conservation attention in the various Australian jurisdictions. We then explore, in two case studies, how the Australian jurisdiction-based approach to listing can lead to the listing of a population of a species as a threatened species in situations where anorganism's distribution is independent of state boundaries. The first case study is on the Southern Hairy-nosed Wombat (Las iOl'h in liS /alijrolls) which was listed in New South Wales (NS W) in 1997 not as an endangered population, but as an endangered species, following the discovery of two small populations on the edge of its range in the south-west of the state. [thas not been listed in the other jurisdictions in which it is present. The second case study looks at the Little Tern (Sterna a/bijrons), which is listed as a species in four states (endangered in Queensland and NSW) and as an endangered sub species (s. a. sil1ensis) in Tasmania, but is not listed federally. Inconclusive molecular data resulted in the scientific committee rejecting the nomination on the grounds that the southern population was not sufticiently distinct from the more abundant northern population. The listing of the Little Tern by the states is therefore intrinsically more precautionary as it deals with a subset of the species and is acting as a defacto population level listing.
We discuss how we might reconcile state versus federal listing of populations by shifting the emphasis in conservation legislation away from the listing of categories of organisms as the primary trigger for conservation actions. Instead, we support suggestions that we should be focusing attention on reducing 'threatening processes', benefiting many threatened species simultaneously, and enhancing processes, such as migration, that are relevant to maintaining evolutionary potential.