Mosses, perhaps because of their small size and seemingly inconspicuous role in nature, have been little studied genetically or phylogenetically. Based on what data do exist, mosses appear to show ranges of genetic variation similar to that known for other land plants. There is little understanding, however, of the influence of ecological determinants and life history characteristics on the genetic structure of natural moss populations. Like homosporous ferns, moss species show a high incidence of polyploidy (multiple sets of chromosomes), nearly 80%. Unlike other land plants, however, most polyploid moss species have been presumed to arise locally and spontaneously, that is by autopolyploidy, rather than by hybridization with nearby species, or allopolyploidy. Faculty adviser Robert Wyatt will direct graduate student Gregory Derda in an intensive genetic survey of several species of the hair-cap mosses of the Pacific Northwest, a region of great diversity in this group. They will use horizontal starch-gel electrophoresis to determine levels of genetic variation in several species, including groups where polyploidy is known or suspected. On the basis of fixed heterozygosity of allozymes, it appears that both Polytrichum ohioense and P. pallidisetum are allopolyploids, one progenitor of each being P. commune. But the other progenitors are unknown. A thorough survey of genetic markers of all species in the region should reveal likely ancestral stocks, and provide data for analysis of phylogenetic relationships among the numerous species. As well, the study will reveal what levels of genetic variation are correlated with areas of glacial refugia in the Pacific Northwest and in areas of recent colonization.
