Frontiers of Biogeography

Islands are ideal research models to study ecological processes, as they vary in size, ecological conditions, and have clearly defined boundaries. Despite great advances in island research, comprehensive understanding of numerous aspects in island ecology is still lacking. Open questions include the effects of spatial scale on island biodiversity, community assembly processes, and the diversity of species forms and functions on islands. Here, I review recent studies investigating species assembly processes and resulting diversity patterns on small islands at local and global scales. I discuss how small-island communities are shaped by environmental, population-level, and species-level processes that differ in strength with island area. Functional trait-based approaches better explained these patterns than measures of species richness on small islands. Detailed ecological understanding of community assembly processes on islands is of paramount importance to conserve biodiversity in an increasingly fragmented natural world.