A major challenge in ecology is to explain the distribution of biodiversity. Islands are natural laboratories for studying biodiversity and species evolution. The recent integration of phylogeny and community ecology provides novel insight into mechanisms driving community assembly. However, phylogenetic community ecology studies on the island ecosystems are still rare. We surveyed plant communities on 40 islands in South China Sea, and asked the following questions: 1) What are the relationships between plant species richness and island area, distance to mainland, and altitude? 2) Are the distributions of species on the islands random or nonrandom with respect to phylogeny? 3) What’s the maintaining mechanism? We established 100 square meters plots on each island and recorded species richness and traits in each plot. We also obtained the DNA sequences for every species.
Results/Conclusions
Our results showed that the number of plant species is positively correlated with island area and altitude, but negatively correlated with distance from mainland, in a pattern consistent with the theory of island biogeography. The plant communities on the large islands are less phylogenetically related than small islands, low altitude islands are more phylogenetically related than high altitude islands, and close-to-mainland islands are less phylogenetically related than far islands. In general, with increasing number of species on an island, the species tend to be less phylogenetically related. This study demonstrates that the three factors, namely area, distance and altitude, play a very important role in determining species richness on the islands and phylogenetic information offers an evolutionary perspective of the species assemblages in community ecology.