The patterns of species distribution over space and time can provide insights in to fundamental ecological processes and provide guidelines for conservation action. Much of the insights into ecology and evolutionary biology have come from the study of island systems. Ecosystems on islands are less complex than their continental surrogates and can provide understanding of the dynamics and evolution of populations and communities. Darwin’s (1872) and Alfred Russel Wallace’s (1878) theory of evolution through natural selection wasdeveloped by observations of species on island archipelagoes. The fundamental law describing the relationship between island species richness and area, where the number of species on an island is positively related to the island area and negatively to distance from the mainland was proposed by MacArthur and Wilson (1967). This theory has been applied to predict how many species would be lost if an area of a particular size is deforested, and the size and shape of nature reserves (Wilson and Willis, 1975). We now examine patterns of bird, butterfly and fresh water fish distributions in the main island groups in the Andamans and interpret it in the light of biogeographical patterns.