How well do phylogenetic studies inform the conservation of Australian plants?

Abstract

Conservation of Australian plants depends on a spectrum of activities from descriptive and experimental biological studies to active management and restoration of wild ecosystems by local communities who value their native biota. On the basis of the premise that available resources for conservation will not allow for all threatened biodiversity to be saved, some systematists and conservation geneticists argue that phylogenetic relationships should be used to set conservation priorities. The principle advocated is that characters, not species number, should become the currency of conservation, that cladistic analysis of phylogenetic pattern provides a predictive means of modelling the underlying distribution of characters among taxa, and that priority should be given to that subset of taxa with the greatest number of character states.

This approach has been applied for some time in the conservation of genetic resources within species (e.g. Eucalyptus caesia), and has been an extra impetus for action with taxonomically isolated endangered species such as the recently discovered araucarian Wollemi pine (Wollemia nobilis). However, most plant conservation activity in Australia has paid little heed to phylogenetic relationships. Degree of threat has been a driving motivation, with endangered species receiving legislative and management attention irrespective of their systematic relationships. Moreover, the current revolution in understanding plant phylogeny associated with DNA sequence studies highlights the need for caution in accepting results of morphologically based analyses. A series of studies on the kangaroo paw and bloodroot family Haemodoraceae highlights this cautionary tale.

The derivation of phylogenetic principles relevant to ecosystem and landscape processes is a new field of some promise to conservation managers. An understanding of the Gondwanan origins and landscape evolution of the south-west Australian flora provides a useful case study. Scaling up phylogenetic knowledge of genetic resources within species, and of the evolutionary relationships of taxa to an integrated overview of best management practices for all taxa at the local landscape level, is perhaps the most effective contribution phylogeneticists might make to help conserve Australian plants.