Phylogenomic data reveal four major clades of Australian Gnaphalieae (Asteraceae)

Within tribe Gnaphalieae (Asteraceae), the Australasian clade is one of the four major clades. In Australia, the Gnaphalieae account for 488 species or approximately half of the native Asteraceae, encompassing wide ecological and morphological diversity including shrubs, everlasting paper daisies, cudweeds, alpine cushion plants, and ephemeral herbs in the arid zone. The evolution of the Australasian clade is still poorly understood. The most detailed previous infratribal classification of Gnaphalieae has recently been revised, resulting in the recognition of two subtribes, with all Australian species placed in subtribe Gnaphaliinae. The most comprehensive previous phylogeny of Australian Gnaphalieae used high-copy ribosomal and chloroplast markers but showed limited resolution and branch support. We used conserved ortholog set data produced with sequence capture and 53 chloroplast genes to infer nuclear and chloroplast likelihood phylogenies for Australian Gnaphalieae, generating data for at least one species each from 80 of the 86 native genera. Four major clades were resolved: the Euchiton clade of cudweed-like and alpine perennial species; the shrubby Cassinia clade; the predominantly perennial and eastern Australian Waitzia clade; and the predominantly ephemeral and western Australian to Eremaean Angianthus clade. The Cassinia, Waitzia, and Angianthus clades are largely congruent with “groups” in a previous morphological analysis and classification of Gnaphalieae. Analysis of ancestral ranges implied the temperate Southeast of Australia as the most likely area of origin for the Australian Gnaphalieae as a whole and for three of the four major clades. The Angianthus clade was implied to be ancestrally Eremaean, with a major secondary radiation originating in southwestern Australia. Our broadly sampled phylogeny provides a framework to inform sampling and design of future studies to test the circumscription of genera.