Tropical forests are extremely diverse. One can find more than 1000 species of trees within a few square miles in many areas. For comparison, the entire U.S. contains about 600 species. It is also common to find many closely-related species in close proximity, despite predictions that close relatives should share similar traits and therefore competitively exclude one another. One phenomenon that may explain this pattern is that species composition can change dramatically with habitat. This idea will be tested by studying five common and diverse tree lineages that occur in three distinct forest types, surveying all of their species across large areas of Peru and French Guiana. Floras of both countries are highly diverse yet share very few species; this allows a powerful, replicated test of habitat specialization. DNA will be used to construct phylogenies of these five lineages to test if close relatives are generally found in different environments. Finally, a reciprocal transplant experiment will help determine whether closely related tree species share traits that confer flood tolerance, nutrient use efficiency, and defenses against natural enemies, and how these traits benefit survival in each habitat.
This project will determine the relationship between environmental heterogeneity, habitat specialization and species coexistence. The results will have importance to policy makers interested in conserving the forests with the highest biodiversity on Earth. The project will provide research opportunities for students within U.S. institutions and will also foster international exchange among the three countries by including Guianan and Peruvian students.
