Evolution of Functional Traits in the Melastomataceae

Fabian A. Michelangeli and collaborators

As the earth's climate changes in response to accumulating greenhouse gases like carbon dioxide and methane, plant species will adapt to changing climate, experience changes in geographic distribution, or become extinct, with such impacts predicted to be most severe in the tropics. Functional traits such as the rate of photosynthesis, leaf thickness, and growth rate can be used to assess the ability of plant species to respond to climate change. In this planning visit, US researchers will work with Costa Rican collaborators to collect preliminary data and plan a larger project on functional traits found in the tropical plant family, Melastomataceae. This is one of largest families of flowering plants with species found from lowland forests to high elevation cloud forest. The family exhibits extreme diversity in size, floral morphology, and growth rate across such elevational gradients. Knowledge of how growth rate and other functional traits are distributed among different lineages in this family will help us understand how tropical plant species might adapt to variation in climate.

An international team of physiological ecologists and systematists will collect preliminary data on functional traits for melastome species on Costa Rica's Volcan Barva Transect, which extends from Atlantic coast lowlands at La Selva Biological Station to 2880 m near the summit of Volcan Barva. Traits to be sampled include life history, growth form, and plant height as well as characteristics important for plant response to climate such as leaf area, the ratio of leaf area to sapwood area, leaf thickness, leaf toughness, and wood density. For the most accessible sites, photosynthetic rate will also be measured. This information will provide the basis for a proposal for a larger project that will more intensively sample the transect. Such data on functional traits would then be combined with phylogenetic data from other sources to elucidate the potential for adaptation to climate change.

Collaborators come from Wilkes University, the University of Maryland, the University of Wisconsin, the University of Costa Rica, the National University of Costa Rica, the California Academy of Sciences and the New York Botanical Garden. U.S. and Costa Rican students will participate in data collection and tropical field work, helping to develop of the next generation of tropical field biologists as scientists and as advocates for preserving functional tropical forests. Outreach activities will be performed in the U.S. via museum and botanical garden partners, as well as in Costa Rica.