Large-scale environmental changes such as aridification have shaped and continue to influence the evolution and composition of biomes. As conditions change, organisms may persist in some parts of their ranges, become extinct in others, or may migrate into newly available or previously inaccessible ecologically favourable regions. Much of Australia is covered by an arid zone that has developed over the last 15 million years. The Australian arid zone (AAZ) provides an excellent location for exploring the influence of continent-scale aridification on biome assembly. The unique flora that inhabits the AAZ includes plants that have responded differently to climate and landscape changes.
In a recent study published in AoBP, Anderson et al. investigate populations of the widespread AAZ grass Triodia basedowii to determine whether there is evidence for a recent range expansion, and if so, its source and direction. Their results show that T. basedowii has recently (within the last 2 million years) expanded across the AAZ. Surprisingly, there was evidence of an expansion origin in central or eastern Australia, while the bulk of the diversity in the group to which T. basedowii belongs exists in western Australia. This evidence for range expansion in an arid-adapted plant is consistent with similar patterns in AAZ animals and likely reflects a general response to the opening of new habitat during aridification. Radiation of the T. basedowii complex through the Pleistocene has been associated with preferences for different substrates, providing an explanation why only one lineage is widespread across sandy deserts.
Ben Anderson is an early career researcher who recently finished his PhD on the systematics and evolution of a group of arid zone grasses (Triodia spp.) in Australia. He developed an interest in plant taxonomy and systematics during his undergraduate degree at the University of British Columbia in Vancouver, Canada, and continued to pursue his interest through an MSc at the Royal Botanic Garden Edinburgh, where he undertook a taxonomic revision of a small genus of tropical Gesneriaceae. During his PhD, Ben focused on resolving evolutionary relationships within a species complex using both traditional (morphology, Sanger sequencing) and newer (genotyping-by-sequencing) methods. He is continuing to develop his bioinformatic skills as a postdoc in the lab of Gitte Petersen at Stockholm University, Sweden, where his current project looks at mitochondrial genome evolution in parasitic plants.