A project undertaken at The University of Sydney, and supervised by Dr Mark de Bruyn.
This project aimed to identify what drivers have caused major changes to the plants and animals of Sahul (Pleistocene Australia and New Guinea). The project sequenced DNA from ancient plants and animals ‘archived’ in sediment cores from the Gulf of Carpentaria. The project hoped to generate pilot data as proof-of-concept to develop a ‘genetic timeline’ for understanding whether climate or humans, or a combination of the two, drove our megafauna to extinction. New scientific tools producing high-resolution datasets such as these are critically needed to understand what led to Late Quaternary extinctions, which resulted in a large reduction in biodiversity worldwide with associated ecological impacts . Climate was a major cause of mass extinction events earlier in Earth’s history, but the Late Quaternary extinctions are complicated by the rise of humans.
Map of the modern Gulf of Carpentaria, northern Australia, showing 11 sedimentary core sampling locations (labelled MD and GC), the potential maximum extent of palaeo- Lake Carpentaria (53 m bathymetric contour, dotted line), the catchment area and rivers flowing into the Gulf (from Chivas et al. 2001, white line).
It is important to understand Australian Late Pleistocene megafaunal extinctions, as they occurred earlier than those on other continents. A number of megafaunal extinctions in Australia occurred between interglacials at a time when climate was more benign and stable than when megafaunal extinctions took place on other continents (Guthrie 2006). Intense debate surrounds the Australian extinctions, as the timing of some of these events appear to coincide broadly with human arrival in Sahul.
This project used ancient environmental DNA examine large scale changes in plants and animals from Sahul, using sediment retrieved from the Gulf of Carpentaria. This region was a large palaeo-lake during periods of the last 130,000 years. To date, sedimentary cores have been sampled and FNA fragments (metabarcodes) have been produced for two major taxonomic groups, spermatophytes and arthropods. However, we have not been successful with amplification of vertebrate DNA. We tried a second method to target this DNA (hybridisation capture) but had no success with that approach either.
We are currently running ‘shotgun sequencing’ that aims to sequence all DNA fragments in an environmental sample. We hope this approach will be successful, and enable us to recover ancient DNA from vertebrates. Our plan is to publish this work as soon as the bioinformatic analyses of these samples is completed.