CONCLUSION

Overall, we found that the response of Hawaiian native tree diversity to precipitation varies across different aged islands on the archipelago. Specifically, we found that all facets of tree diversity strongly responded to precipitation on the older island compared to the younger islands, affecting both local diversity and the turnover of species across habitats with different levels of precipitation. Our findings suggest that macroevolution influences how patterns of diversity respond to the environment, where evolutionary time is needed for new colonizers to arrive or resident species to sort and specialize into different environments. Additional factors that vary greatly across the islands, such as soil diversity and island topography that were not tested here, may also play a role. Finally, we find that the introduction of alien species modifies the precipitation-diversity relationship of native island floras. This indicates that the ongoing invasion of the Hawaiian islands will fundamentally reshape the local biodiversity patterns of trees and the ecosystem services this biodiversity offers.