RUI: A Phylogenetic analysis of subfamily Gesnerioideae (Gesneriaceae) and sequence divergence in a cycloidea homolog.

Dr. James Smith at Boise State University is investigating the evolutionary history of a large tropical plant group, the African violet family Gesneriaceae (a major portion of which occurs in the Americas and not in Africa). The evolutionary history will be studied with comparative gene sequencing, a process that examines genes directly to trace the evolutionary history of the whole organism. Once an evolutionary tree is produced from these data, the history of the organisms will be used for several objectives. 1) Because different forms of floral symmetry occur in this group of plants, the phylogenetic tree will provide a means of determining how often switches from one form of symmetry to another have occurred. 2) Floral symmetry is known to be controlled by a few genes in related plants and the tree will provide a means of examining the evolution of one of these genes in a plant family that has different types of symmetry. 3) The tree will provide a framework for all future investigations among this group of plants, especially evolution of pollination biology and chromosomes.

One of the greatest problems facing systematics is determining homology (where traits have a common evolutionary origin). Phenotypes (physical appearance of an organism) are the result of genes viewed through complex developmental mechanisms operating during the growth of the organism. Similar developmental pathways may result in similar phenotypes across non-related organisms. This uncoupling of developmental homology (identical developmental processes) from phylogenetic homology (identical history) can result in misinterpreting relationships among organisms. Few opportunities have allowed systematists to investigate the genetic mechanisms that underlie phenotypes and the changes in these mechanisms that result in patterns of diversity. The evolutionary history of selected groups of Gesneriaceae will allow an opportunity to examine the changes in floral phenotypes and changes in the genes that regulate these phenotypes to see if they share developmental and phylogenetic homology.