9801495 Columbus The importance of chromosomal change in speciation and its role in producing reproductive barriers has long been recognized as a factor that can lead to morphological diversification. An ideal system with which to study processes of chromosome change is Carex L. (Cyperaceae) one of the largest genera in the world with approximately 2,000 species recognized, which has an extremely wide range of chromosome numbers from n=6 to 68. Three questions will be investigated in this study: 1) What role does change in chromosome number play in speciation in Carex. 2) What mechanisms are involved in cytogenetic change among species within Carex section Acrocystis. 3) What are the relationships among lineages within section Acrocystis and between Acrocystis and other sections of Carex? Molecular phylogenetic analyses of two nuclear and one chloroplast DNA region will be used to create a framework for studying the patterns of chromosomal change measured using chromosome counts, flow cytometric measurements of genome size, fertility among species with different chromosome numbers, and position of repetitive DNA elements such as telomeres on the chromosomes. These four different data sets, together with phylogenetic hypotheses, will be used to indicate both the kinds of chromosomal change and the direction that change has occurred.
