Diversification and biogeography of the Australian cicada genus Pauropsalta

Species distributions and richness patterns can be shaped by major historical climate events. Over the last 30 million years, the climate of the southern hemisphere has undergone dramatic cooling and drying due to the establishment of a circum-Antarctic current and a change in global CO₂ levels. In Australia, arid biomes greatly increased as the continent migrated to the northwest. Studies of non-invertebrates suggest that arid-adapted biota have diversified throughout the last 20 million years. It follows that invertebrates have undergone similar evolutionary diversification but few have been studied. My research focuses on the largest genus of Cicadettine cicadas in Australia, Pauropsalta, which is endemic to Australia and distributed throughout all biomes. My research addresses the following questions: 1) What are the relationships among species within Pauropsalta? 2) Are there any changes in diversification rate over time in the Pauropsalta phylogeny, and if so, which clades are associated with the rate change? 3) Do increases in diversification rate along select lineages correspond with movement into a new habitat? To address these questions, I generated a molecular phylogeny of the genus Pauropsalta based on five loci (4 nuclear and one mitochondrial) for 163 species. My analyses suggest that Pauropsalta did not originate in the arid zone but rather in the monsoonal wet tropics in the north with multiple invasions into the arid zone. Diversification rates of those taxa in the arid zone do not show an increase in diversification rate, which has been found in squamates.