Some of the most basic questions in ecology are 'How are ecological communities assembled and maintained?' and 'Why are there more species in some communities than others?'. Elevational gradients offer interesting opportunities for answering these questions due to highly heterogeneous environmental conditions across small geographic extent. The magnitude of variation across elevations in climate as well as species communities, parallels that across latitudes, but lends itself more easily to studies using primary data. Therefore, elevation becomes a proxy variable for a large number of potential mechanisms driving ecological patterns. This makes understanding patterns in species communities across elevations an important objective in ecology.