My research investigates the origin and maintenance of Amazonian rain forest tree diversity. I am especially interested in the role that biotic interactions and environmental heterogeneity play in the morphological, functional, and genetic diversity of tropical trees, and how these factors influence the distribution and speciation of plants. An ideal study system is the endemic flora found on the many white-sand forests that are widely dispersed in patches throughout the Amazon basin. These ancient white-sand deposits constitute habitat islands, surrounded by other terra firme forests on more fertile soils, and they harbor edaphic-specialist tree species that are often closely related (if not sister taxa) to congeners on neighboring soil types. The main thrust of my research is to understand the evolution and maintenance of edaphic specialization by trees to these divergent soil types, and the role of herbivores in this process.
Current projects include 1) an evaluation of the role of soil type and geographic distance in structuring the lineages of geographically sympatric sister species complexes in the genus Protium (Burseraceae) that are associated with divergent soil types across the Amazon basin 2) an investigation of the role of trait evolution (including antiherbivore defenses), phylogenetic relatedness, and habitat specialization in the assembly of Amazonian plant communities and 3) testing the relative importance of time, area, colonization history, and the evolution of morphological innovation in the diversification of the sister families Anacardiaceae and Burseraceae.
To ask these questions, we work in the field and in the laboratory. We conduct floristic inventories, reciprocal transplant experiments, physiological measurements (including plant defense chemistry), and collect molecular data at both the population and species-level.