Carving up Australia's arid zone: a review of the bioregionalisation of the Eremaean and Eyrean biogeographic regions

The Eremaean region, Australia's arid biome and biogeographic region, has been discussed by botanists (and as the Eyrean, its counterpart for zoogeographers) for over 150 years, yet little progress was made in defining it as an area of endemism until the 2000s. As Australia's largest biome and biogeographic region, the Eremaean has been defined in a climate sense, but is a historically composite biogeographic area. Taxa that inhabit the Eremaean (Eyrean) tend to display sister relationships to those outside the biome in temperate and monsoonal biome areas, indicating that two or more temporally discordant distributional patterns exist in the Australian flora and fauna. The future of Eremean and Eyrean bioregionalisation will need to incorporate these temporal patterns when constructing new bioregionalisations and historical and climate-based biogeographic models.