The phylogenetic Biology of the Paleotropical Tree Genus Lithocarpus (Fagaceae)

Duke University, Durham NC

Investigators

Abstract

Dr. Paul Manos of Duke University is studying the predominantly paleotropical tree genus Lithocarpus (ca. 300 species) to better understand the biological significance of variation in fruit morphology and DNA sequences across a diverse landscape. Modifications of the common acorn-like fruit typically mark subgroups within the genus, but such changes appear to have evolved more than once. The study will explore new quantitative methods to characterize changes in fruit shape and compare and combine these data with DNA sequences to test whether certain fruit types have multiple origins. The widespread distribution of Lithocarpus on the continent of Asia and throughout the Malayan Archipelago also provides an excellent opportunity to pursue the genetics of plant demography using chloroplast DNA variation, a maternally inherited marker that tracks seed movement. By sampling individuals throughout the range of the genus, the study will address the relationship between plant migration and geological/paleoecological change. A variety of methods will be used to test explicit hypotheses of refugial areas and migration routes based on paleoecological data. Trees will be sampled to examine genealogical structure within populations through contrasting nuclear and cytoplasmic molecular markers with reference to taxonomy, geography, and differential patterns of genome evolution. The study of organismal diversity and molecular evolution in tropical tree species requires a framework built upon thorough knowledge of natural history, taxonomy, morphology, and genealogical relationships. Species in the oak family present a broad spectrum of opportunities to study diversity in form and patterns of plant migration and gene flow. Tropical woody plants are poorly studied in this regard and a variety of basic biological questions have never been addressed in the ecologically important relatives of the oaks. Given the amount of carbon storage, ecosystem services, biodiversity, and physical structure provided to the tropical rainforest by this tree community, this study would be one of first of its kind to apply several powerful molecular techniques to an important tropical genus.