Modern molecular methods are revitalizing the study of fern systematics and evolutionary biology. In particular, analyses of protein isozymes and other gene markers now enable researchers to determine the parental species involved in hybridization events and in polyploid evolution (change through chromosome doubling). Coupled with new techniques for investigating variation in chloroplast DNA, these approaches hold great promise for determining the phylogenetic relationships of groups of ferns. Dr. Chris Haufler of the University of Kansas continues to pioneer the use of new molecular methods in resolving long- standing taxonomic problems in fern biology. This project will focus on a circumboreal group of ferns of the Polypodium vulgare complex. In addition to molecular data, new morphological data from spore studies and leaf shape will be used to delimit species in nature, identify hybrid populations and polyploids, and test whether polyploid hybrids occur rarely or commonly. These results will then permit more rigorous comparisons of the modes and mechanisms of speciation in ferns with those known for flowering plants.