Accumulating evidence for a dispersal biogeography of southern cool temperate freshwater fishes

Aim This paper seeks to understand the biogeography of southern cool temperate freshwater fishes in the context of diverse aspects of their natural history. Location The fish families discussed are found widely in southern cool temperate lands: in Australia, New Zealand, Patagonian South America and southern Africa, as well as some of the smaller, remote southern oceanic islands. Methods The review is based on literature and primarily examines the association between distribution patterns and diadromous (sea-migratory) life histories. Results The broad distribution of freshwater fishes of the lamprey families Geotriidae and Mordaciidae and the salmoniform. Galaxiidae and Retropinnidae in the southern cool temperate zone, has caused prolonged perplexity and debate. Arguments in favour of both a dispersal biogeography and a Gondwana-based vicariance biogeography have been presented. These are not necessarily alternatives. Main conclusions Evidence from: 1 Distribution patterns in relation to life-history strategies; 2 Genetics and morphology; 3 Different elements in the New Zealand fauna and their relationships; 4 Recent dispersal events; 5 Geological history of the Falkland Islands and the relationships of its freshwater fishes; and 6 Parasitology; all support, or are consistent with, a dispersal biogeography of this southern cool temperate fauna. The groups involved are sufficiently ancient to have formerly inhabited Gondwana, but no compelling evidence indicates that present distributions reflect a former broad Gondwana-based range. A role for dispersal in these fishes is consistent with increasingly common claims for dispersal in other taxa. This does not mean that there was no ancient influence from Gondwanan vicariance.