Environmental influences on sex ratio and spatial distribution of dioecious Morella cerifera L. on a Virginia barrier island.

Abstract

ENVIRONMENTAL INFLUENCES ON SEX RATIO AND SPATIAL DISTRIBUTION OF DIOECIOUS MORELLA CERIFERA L. ON A VIRGINIA BARRIER ISLAND. By Molly Margaret Hokkanen, B.S. A Thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Biology at Virginia Commonwealth University. Virginia Commonwealth University, 2013 Major Advisor: Donald R. Young, PhD Professor and Chair, Department of Biology For dioecious plant species, sex ratios within a population depend on multiple environmental and life history characteristics. Sex ratio is an indicator of population health and can be a predictor for genetic bottlenecking. My study established the previously unknown sex ratio for the shrub, Morella cerifera, on a Virginia barrier island. The ratio was compared with multiple environmental and reproductive traits to determine their potential influence on sex determination and/or distribution of male and female plants. Multivariate analyses were used to identify relationships between sex, sex ratio and environmental drivers. The sex ratio for M. cerifera changed depending on scale. The entire island ratio did not vary significantly from 50:50, based on a Chi-squared analysis. Different spatial scales resulted in different and more variable sex ratios. The environmental variables measured did not suggest any relationships with sex or sex ratio. Future studies with a focus at multiple spatial scales may elucidate the connection between environment and sex ratios for M. cerifera.