What Tropical mountain regions represent the global hotspots of vertebrate species richness, but the evolutionary processes that have generated the high diversity of these areas remain poorly understood. In my fellowship, I will address this issue by testing the relative importance of historical rates of dispersal, diversification and lineage persistence in generating the variation in species richness found across the world's mountain areas. I will determine these trends for the most diverse avian order, passerines (~6,500/10,000 global bird species). These analyses are of crucial importance to improve our understanding about why biodiversity is so heterogeneously distributed across the earth's surface. Why Mountain areas support as much as 1/3 of the world's terrestrial species diversity, a far greater number of animal and plant taxa than predicted by their area or current environmental conditions. Yet, despite extensive study, biologists are still unable to conclusively answer why mountains are so rich in species? Considering the poor predictive ability of present day environmental variables, it is imperative to determine the influence of evolutionary history in generating the high species diversity of mountain regions, particularly those located in the tropics. My work will directly quantify these influences, and the importance of evolutionary process in mountains for the formation of global gradients of species, phylogenetic and functional diversity. How I will generate a comprehensive species-level dataset for passerine birds at the global scale. This will encompass a time-calibrated phylogeny, eco-morphological trait data and regional delimitations of the world's mountain areas. With this data, I will use phylogenetic comparative methods to test how rates of dispersal, diversification and persistence have varied between mountains and lowlands over evolutionary timescales, in addition to the relative importance of these processes in generating the geographic variation in species diversity among these areas. These analyses will determine whether mountain areas are a significant contributor of species, phylogenetic and functional diversity to lowland areas, and thus their importance for global biodiversity. SSR Mountain areas are of vital importance for human societies, not only because they support such a high proportion of the earth's biodiversity, but because they provide a wide variety of key ecosystem services that humans depend upon. For example, almost half of the world's clean drinking water is sourced from mountain areas. Maintaining these ecosystem services is of paramount importance for the continued health of human societies, however, achieving these objectives also represents a major challenge of the future. By significantly improving our understanding about the formation and evolution of montane biota, my fellowship can provide a direct quantification of the importance of maintaining the conditions that have stimulated the evolution of these complex and valuable ecosystems.