title: Untangling a species complex of arid zone grasses (Triodia) reveals patterns congruent with co-occurring animals.
abstract: The vast Australian arid zone formed over the last 15million years, and gradual aridification as well as more extreme Pliocene and Pleistocene climate shifts have impacted the evolution of its biota. Understanding the evolutionary history of groups of organisms or regional biotas such as the Australian arid biota requires clear delimitation of the units of biodiversity (taxa). Here we integrate evidence from nuclear (ETS and ITS) and chloroplast (rps16-trnK spacer) regions and morphology to clarify taxonomic boundaries in a species complex of Australian hummock grasses (Triodia) to better understand the evolution of Australian arid zone plants and to evaluate congruence in distribution patterns with co-occurring organisms. We find evidence for multiple new taxa in the T. basedowii species complex, but also incongruence between data sets and indications of hybridization that complicate delimitation. We find that the T. basedowii complex has high lineage diversity and endemism in the biologically important Pilbara region of Western Australia, consistent with the region acting as a refugium. Taxa show strong geographic structure in the Pilbara, congruent with recent work on co-occurring animals and suggesting common evolutionary drivers across the biota. Our findings confirm recognition of the Pilbara as an important centre of biodiversity in the Australian arid zone, and provide a basis for future taxonomic revision of the T. basedowii complex and more detailed study of its evolutionary history and that of arid Australia.
authors.affiliation: School of Plant Biology, The University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia; Kings Park and Botanic Garden, Botanic Gardens and Parks Authority, Fraser Avenue, Kings Park, Western Australia 6005, Australia. Electronic address: banderson2914@gmail.com.
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Anderson
authors.affiliation: School of Plant Biology, The University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia; Kings Park and Botanic Garden, Botanic Gardens and Parks Authority, Fraser Avenue, Kings Park, Western Australia 6005, Australia.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Barrett
authors.affiliation: School of Plant Biology, The University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia; Kings Park and Botanic Garden, Botanic Gardens and Parks Authority, Fraser Avenue, Kings Park, Western Australia 6005, Australia.
authors.forename: Siegfried L
authors.initials: SL
authors.lastname: Krauss
authors.affiliation: School of Plant Biology, The University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia; Western Australian Herbarium, Department of Parks and Wildlife, 17 Dick Perry Ave, Kensington, Western Australia 6151, Australia.
authors.forename: Kevin
authors.initials: K
authors.lastname: Thiele
mesh_terms: D000818:Animals; D001315:Australia; D044822:Biodiversity; D005075:Biological Evolution; D002736:Chloroplasts / Q000235:genetics; D018744:DNA, Plant / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D010802:Phylogeny; D018515:Plant Leaves / Q000235:genetics; D006109:Poaceae / Q000145:classification* / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D018744:DNA, Plant
keywords: Hybridization; Internal transcribed spacer; Molecular phylogenetics; Pilbara; Species complex; Triodia