The formation of the Antarctic Circumpolar Current approximately 30 million years ago drastically changed the climate of Australia producing one of the largest arid biomes on earth. Studies have shown that the aridification of Australia has led to an increase in diversification rates in those organisms that adapted or were pre-adapted to the arid environment. This project aims to explore the climate-related diversification and biogeography of the Australian cicada genus Pauropsalta, which is distributed throughout all Australia's biomes and is thought to have originated during the major aridification events of Australia. 'Next generation' sequencing technology will be used to develop phylogenetic markers to aid in resolving evolutionary relationships among Pauropsalta species. In addition, ecological niche models will be estimated to distinguish the major lineages of Pauropsalta and reconstruct its ancestral biogeography. Incorporating niche models will provide a better understanding of how the aridification of Australia has affected the diversity of Australian biota.
This project will result in the training of three undergraduates in molecular techniques and phylogenetic methods and the further training of one graduate student (in 'next generation' sequencing technology). Each described cicada species will have a page devoted to it on the Encyclopedia of Life with specimen photos and distribution maps. This project will strengthen our international collaboration. Results will be presented at international meetings and submitted to peer-review journals.
This project examined how the aridification of Australia has shaped the distributions and species richness of the native biota. The study system was a large group of Australian cicadas in the genus Pauropsalta that are found in a wide variety of different habitat types and thus provide an excellent model. Over the past ~40 Ma, Australia has been drying out as a result of the formation of the ice sheets in Antarctica and the country’s continued northwestward migration. This has resulted in the arid zone growing to include ~70% of all Australia, while the monsoonal, temperate, and aseasonal wet environments reduced to their current sizes along the perimeter of Australia. Three trips to Australia fostered an international collaboration with Dr. Max Moulds of the Australian Museum. A database was created that included among other cicadas, the ~5000 dried Pauropsalta specimens in his private collection. In addition, the Simon Lab made an extensive collection of Pauropsalta cicadas totaling 1907 alcohol-preserved and dried specimens many of which were used for the genetic and morphological studies in this project. The merging of these two databases resulted in 820 unique specimen localities for 170 species. The collections also resulted in the descriptions of 6 new genera and 33 new species. Created along with the descriptions was a key to both males and females of all described species. This study produced a wealth of genetic data. These include > 3 million nuclear DNA sequences surveyed using next-generation sequencing technologies. In addition, using traditional DNA sequencing technology, 458 specimens were sequenced for a gene located in the mitochondrion, while 170 species were sequenced for 4 genes located in the nucleus. These will be made freely available through the international gene database, Genebank. Two of these genes are new to cicada research. This molecular work also resulted in the training of two undergraduate students in molecular methods and computational methods to analyze the data. In addition, a graduate student and postdoctoral student were trained in next-generation sequencing bioinformatics and computer programming. Results of this research were disseminated in five conference presentations (2 invited); four major publications, including a monograph of the genus, are nearing completion.
