Endemism in Tasmanian cool temperate rainforest: alternative hypotheses

Abstract

Evidence is presented which suggests that hypotheses presented by Kirkpatrick & Brown relating to endemic species in Tasmania are either invalid or of limited importance for woody rainforest species. In their place three hypotheses are presented to account for the presence of endemic species in Tasmanian cool temperate rainforest on the basis of the fossil record and the distribution of species which are closely related to the endemics. The first two hypotheses relate to the presence of the endemic species in the general Tasmanian region. They are: 1 Some species evolved in southeastern Australia during the Tertiary in response to the changing climate. Some of the ancestral species still occur in temperate rainforest at lower latitudes in Australia. 2 Some species have remained essentially unchanged in Tasmania during the Tertiary and Quaternary climatic changes. The third hypothesis relates to the restriction of these cool temperate rainforest species to Tasmania: 1 Post-glacial climatic changes (especially a decrease in rainfall) and the human influence (especially land clearing and fire) may have combined to eliminate some cool temperate rainforest species from mainland Australia.