Human interference on the natural environment including habitat loss and fragmentation has resulted in a great loss of biodiversity and a major extinction crisis. The swamp orchid Phaius australis F.Muell. has a disjunct distribution along Australia’s east coast in occurring in the ecotones of coastal wetlands and springs. The orchids are endangered due to past and current illegal collection, continued habitat loss, limited connectivity between populations and because they are an ecological specialist that occurs in ecosystems that are vulnerable to climate change. This study combines the use of genetic and demographic analysis across a 2 000 km latitudinal range to investigate the viability and persistence of P. australis. Population genetic samples were collected at 34 locations from tropical north Queensland to the southern edge of the subtropics in New South Wales. Paired population demographic assessments were undertaken at 25 of these locations over three years to examine population dynamics, estimate population growth rates and determine a representative lifecycle for the species. A pollination experiment was carried out in a large stable population to test for evidence of self-pollination. Current population vulnerability and vulnerability to future rainfall and temperature changes have been modelled through population viability analysis (PVA) based on climate related vital rates and SimCLIM generated climate change predictions for two emissions scenarios.
Submitted in the fulfilment of the requirements of the degree of Doctor of Philosophy, University of the Sunshine Coast, 2016.