Thesis

Phylogenetic Assessments for California's Highest Risk Mammals

Anthropogenic activities have severely impacted much of the life on Earth. To protect and preserve our remaining natural areas, conservation biology has traditionally focused on the impacts of humans on natural systems. Recently, conservation biology has incorporated phylogenetic metrics to better understand the evolutionary value of imperiled species. All extinctions include the loss of some biological value, but extinctions of many closely related species result in a disproportionate loss of evolutionary history relative to the same number of extinction events among distantly related species. Mammals are one of the most well-studied groups in phylogenetics, making them ideal candidates for evaluating the loss of evolutionary history that accompanies extinction. I use data collected from a published phylogeny on California’s native terrestrial mammals to investigate the relationships between conservation status, as a proxy for extinction risk, and phylogeny. I examined the potential losses of phylogenetic diversity and disparity by calculating the change in Phylogenetic Diversity (PD) and Net Relatedness Index (NRI) when species with elevated extinction risks were pruned from the California mammalian tree of life. These analyses reveal that the potential loss in PD and NRI is equal to or even lower than expected from a random loss of the same predicted number of species. These results are consistent with global trends for mammals, but show how this global pattern is also present at some regional scales, which is not always the case in previous investigations.

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