The impacts of climate change on an Australian arid zone gecko species (Gehyra variegata)

"This thesis is presented for the degree of Doctor of Philosophy.""March 2013"Thesis by publication.Thesis (PhD)--Macquarie University, Faculty of Science, Department of Biological Sciences, 2013.Includes bibliographical references.1. Introduction -- 2. Designing molecular tools -- 3. Dispersal and species distribution modelling -- 4. Estimating genetic loss -- 5. Phylogeography and refugia -- 6. Forest structure and dispersal characteristics -- 7. Final discussion -- Appendices.In 1859 Charles Darwin acknowledged the difficulty in predicting the likely impact of environmental change to biodiversity. During this century rapid global climate change (GCC) is likely to have a profound effect on the distribution and evolutionary fate of biodiversity. Thus predicting how species will respond to climatic fluctuations is one of the most important contemporary questions in conservation biology. Here, I explored the impact of past, present and future climates on a widely distributed Australian gecko, Gehyra variegata, using an interdisciplinary approach. To make more realistic estimates of a species' likely future distribution I incorporated a genetic estimate of dispersal into species distribution models (SDM). The data suggested a large proportion of the current distribution will fail to colonise the predicted future distribution, and will result in a significant reduction to current levels of genetic diversity. Phylogeographical analysis suggested that higher levels of genetic diversity for this species have been associated with the channel country in arid Australia since the Pleistocene. This region has the highest water run-off throughout the arid biome and has been an important environmental feature to help the species persist through past unfavourable climatic conditions. However, it is unlikely to maintain favourable conditions in the near future due to increasing aridity. Corridors of natural habitat are often considered a conservation solution to help species disperse between habitat patches and maintain geneflow, although natural habitat can also experience structural changes over space and time which may influence connectivity. I revealed that structural changes reduced the number of retreat sites for this species, which influenced levels of dispersal and rates of predation. My data suggests the evolutionary fate of this species is likely under threat in the near future and careful consideration needs to be given to future land usage if we wish to protect biodiversity.Mode of access: World wide web1 online resource (xiv, 309 pages : illustrations, maps