Determining Impediments to Gene Flow in a Natural Population of Cornus florida L. Cornaceae, Using Integrative Landscape Genetic Techniques

Abstract

DETERMINING IMPEDIMENTS TO GENE FLOW IN A NATURAL POPULATION OF CORNUS FLORIDA L. CORNACEAE, USING INTEGRATIVE LANDSCAPE GENETIC TECHNIQUES By Crystal A. Meadows, M.S. A thesis submitted in partial fulfillment of the requirements for the degree of Masters of Science at Virginia Commonwealth University. Virginia Commonwealth University, 2011 Major Director: Dr. Rodney J. Dyer, Associate Professor, Department of Biology This study examined the impact intervening environment has on gene flow in the insect pollinated understory tree, Cornus florida L., by combining GIS and landscape genetic techniques (Least Cost Path Analysis, Circuit Theory, and Conditional Genetic Distance). Traditional population genetic analysis indicated pair-wise relatedness was significantly correlated to distance (Pearson; r = -0.312, P < 0.001) suggesting a spatial component to offspring relatedness. Dispersal throughout the study site was non-random, exhibiting a high degree of pollen pool structure due to restricted gene flow (Two-Generation Analysis; Φft = 0.161, P = 0.001). Forest structure was quantified in GIS layers representing coniferous canopies, mixed hardwood canopies, C. florida canopies, open understory (roads), and open understory/canopy due to tree removal. Of these layers, landscape isolation for the roads layer provided the best-fit model for describing genetic differentiation among sampled pollen pools (Mantel; r = 0.542, P = 0.001). These data also suggest that improved biological inferences can be gained by examining a range of landscape isolation models.