This study aims to investigate the hypothesis that a big island can be divided into a number of smaller islands, which have the same pattern of area-species curve as the real islands do. To address this question, we use published data on amphibians and reptiles and their distribution on the island of Puerto Rico and landbridge islands of the Puerto Rican Bank, which were frag-mented from the main island only within about 10,000 years ago. Several different methods of sub-dividing the island into smaller semi-islands are employed. Our results show that in Puerto Rico there are correlations between the number of species and area available at different elevations and between species and area after removing effects of elevation. Nevertheless, the nature of correlation seems to change along the elevation gradient. Further analyses demonstrate that elevation plays a particularly important role in explaining reptile and amphibian distribution, while rainfall exerts the least effect on determining herpetofauna diversity among other factors. The study results indicate that area-species correlation is likely a consequence of habitat heterogeneity of the island.