Species in the early stages of diversification serve as excellent models for studies of the environmental conditions that drive speciation. The highly variable Hawaiian tree, Metrosideros polymorpha ('Ohi'a), is such a species, having derived from a progenitor that colonized the Hawaiian Islands from New Zealand as recently as 0.5 to 1.0 million years ago. Several of 'Ohi'a's varieties co-occur across the volcanic islands, which range in age from the environmentally stable, 5-million-year-old Kauai to the still-forming and highly heterogeneous Big Island. As such, 'Ohi'a provides an ideal system in which to examine the relationship between spatial and temporal environmental heterogeneity and the evolution of reproductive isolation, a precursor to speciation. This two-year study will use hand-pollinations, microscopy, and growth chambers to determine the relative cross-fertility within and between varieties and the viability of the resulting seedlings under a range of conditions. The proposed work will help to illuminate the environmental conditions under which speciation in out crossed tree species will occur.
The work will involve the training of several undergraduate students and one M.S. student in evolutionary theory, field methods, and the scientific process. Recruitment of students will target under-represented groups at UH-Hilo, a Minority and Native Hawaiian-serving Institution. Further, the research projects developed through this grant will be modified by the P.I. into lecture and laboratory exercises in upper-undergraduate and graduate courses.
