Investigating Australian mammal extinctions and conservation using ancient DNA, population genetics and time-series analysis

Abstract

Biodiversity loss is a global problem with potentially catastrophic consequences for ecosystem function, human health and economics. Australia has one of the highest rates of species extinctions in the world, and the continents’ unique mammal fauna have suffered disproportionately. To minimize further mammal extinctions, conservation efforts should be focused in areas where they can be most effective. These efforts can be assisted by research that investigates species extinction risk in changing environments and that identify strategies to minimise biodiversity loss with limited resources. Extinction science is a multidisciplinary field that aims to improve our understanding of extinction risk and the conservation interventions that can alleviate it. The field incorporates ideas and data from palaeontology, field studies and genetics to understand all aspects of species declines and to apply this understanding to conservation efforts. In this thesis I aim to improve our understanding of Australian mammal extinction and declines, and to apply current knowledge to aid future conservation efforts. I answer a variety of questions related to Australian mammal extinction and conservation by analyzing ancient DNA, population genetic and radiocarbon age time-series datasets. Specifically, I use: • Genetic population assignment to test the origins of a putative relict population of the Tasmanian devil (Sarcophilus harrisii) on mainland Australia—Chapter 2. • Time-series analysis to validate the common assumption of synchronous extinction of the Australian mainland devil and thylacine (Thylacinus cynocephalus)—Chapter 3. • Ancient DNA analysis to reconstruct the phylogeography and demographic history of thylacines leading up to their extinction on both the Australian mainland and Tasmania— Chapter 4. • High-resolution genetic monitoring to evaluate the success of reintroduction programs in maintaining the genetic diversity of four species of threatened Australian mammals: The greater stick-nest rat (Leporillus conditor), the western barred bandicoot (Perameles bougainvile), the burrowing bettong (Bettongia lesueur) and the geater bilby (Macrotis lagotis)—Chapters 5 and 6. Ultimately, I resolve several natural history questions that have conservation implications for Australian mammals today, using a variety of cutting edge technologies and analytical methods.