I study how the spatial and temporal arrangement of habitats influences biological diversity. This issue relates to a number of fundamental questions in ecology that have challenged scientists for decades. Questions include: Why do mountains have extraordinary biodiversity? What is the importance of niche partitioning in maintaining biological diversity? and How does the climate history of a region influence its current patterns of biological diversity? Addressing these types of questions requires integration from a range of fields, including ecology, evolutionary biology, biogeography, climatology, geology and conservation biology because mechanisms that influence biological diversity are played out across a range of spatial and temporal scales. Much of my current work is focused on the role of plant-hummingbird interactions in the generation and maintenance of high tropical diversity; however, I also work on multiple other systems and questions including drivers of global diversity and, most recently, of European montane plants.