Evolutionary conservation genetics of invasive and endemic parrots

The world is now thought to have entered into a sixth mass extinction event, which unlike previous mass extinctions, is entirely driven by human impacts. The early colonisation of humans has led to as many as a thousand endemic bird species becoming extinct, while increasing human mediated transport of species around the world has led to invasive species becoming one of the largest global conservation challenges of today. Studies in molecular ecology can help us to unravel how evolutionary processes are important for informing conservation and invasion biology by understanding genetic mechanisms that enable populations to grow and adapt in a changing world. As genetic diversity is essential for the persistence of populations, this thesis aims to understand how species respond, at a genetic level, to human-driven events such as the reduction of a population to a small size, or the introduction of a species into a novel environment. The findings demonstrate the important use of genetic markers for phylogenetic reconstruction and understanding population structure. These phylogenetic reconstructions examine taxonomic distinctiveness and patterns of evolution, and allow the identification of ancestral origins for invasive ring-necked parakeets. Evidence from genetic phylogroups, trade data and drivers of population growth, highlight how multiple introductions and patterns of climate matching between the native and invasive ranges of ring-necked parakeets, are mechanisms for invasion success. In contrast to mild genetic bottleneck effects, high levels of diversity and the avoidance of problems associated with small population size within populations of invasive ring-necked parakeet, the endemic Seychelles black parrot exhibited a reduction in population size and reduced levels of genetic diversity over time. Moreover, the inclusion of new genetic data for a number of extinct parrot species enabled an examination of the loss of broader scale phylogenetic diversity, important for ecosystem function, as a result of extinctions of endemic species and invasions of ring-necked parakeets. The findings from this thesis have already been applied to conservation and invasion biology by contributing to the reclassification of the endemic Seychelles black parrot, and to improving the ability of ecological niche models to predict areas suitable for future invasions of ring-necked parakeets. Furthermore they provide a novel approach to identifying potential candidates as ecological replacements to restore ecosystem function and lost phylogenetic diversity.