Oceanic islands represent a set of systems in which biological diversity varies as a consequence of remoteness or size, not environment; they are also generally simpler than continental ecosystems. Islands therefore provide an opportunity to determine the direct effects of biological diversity on ecosystem function. The volume addresses the components of biological diversity on islands and their patterns of variation; the modern threats to the maintenance of biological diversity on islands; the consequences of island biology and its modification by humanity regarding aspects of ecosystem function; the global implications of islands for conservation; and how islands can help one to understand the processes inducing changes throughout the world.