How Was the Australian Flora Assembled Over the Last 65 Million Years? A Molecular Phylogenetic Perspective

Abstract

Australia has a mostly dry, open, fire-shaped landscape of sclerophyllous and xeromorphic flora dominated by eucalypt and acacia trees, with diverse shrubs from a few families such as Myrtaceae, Proteaceae, and Fabaceae. Using molecular phylogenies to test hypotheses derived from the fossil record, we review the principal forces that transformed the ancestral Gondwanan rainforest through the Cenozoic. Today's vegetation is a mix of ancient radiations that have persisted in Australia through dramatic climate change since before the breakup of Gondwana, and more recent lineages whose ancestors arrived by trans-oceanic dispersal. Signatures in the fossil record of lineage turnover and trait evolutionary change are detected in phylogenies, but often at earlier dates. The Australian biota is a sample of the wider region, with extinction of some taxa and radiation of others (due to chance and opportunity), but biotic and abiotic interactions have resulted in a unique flora and fauna.