Global change and the future of avian diversity

Biodiversity in the Anthropocene is declining at an alarming rate. Both ecological and evolutionary components of biodiversity are critical for determining the processes that have led to the biogeographic patterns of biodiversity we see today, as well as understanding the impacts of global change on communities and ecosystems. Here, I use unique trait datasets, and phylogenetic relationships, to explore extant and future patterns of avian biodiversity. In the first part of this Thesis, I interrogate global-scale biogeographic patterns of avian diversity, by using avian traits to reveal how species fill and expand niche space. I show that evolutionary history, rather than contemporary environment, drives patterns of extant global trait diversity. In the second part I assess the impact of species extinctions on this diversity and examine whether the loss of trait and phylogenetic diversity is greater than predicted by species loss alone. I find that not only is trait homogenisation expected across the whole Avian class, but that this is borne out spatially, with the majority of biome and ecoregion assemblages predicted to experience a significant reduction in morphological diversity with important consequences for ecosystem functioning. Finally, given that Anthropogenic land-use change is experienced most intensely in the tropics, I move from a broad to local spatial scales, and highlight that the protection of secondary forests should be seen as a priority for the conservation of tropical biodiversity. Overall, this Thesis helps to further our understanding of the origins of biodiversity, and in the face of global change, its conservation.