The Hawaiian Islands possess one of the most distinctive floras in the world. Because of its rich biodiversity and extreme geographic isolation, the Hawaiian archipelago is often praised as an ideal locality in which to study the patterns and processes of organic evolution. However, much of Hawaii's unique flora is endangered because of habitat conversion by humans and introduced animals and through the invasion of alien, weedy plant competitors. Fragmentation of forest habitat in particular may reduce the effective number of mature plants able to reproduce in the wild. There is a critical need, therefore, for studies which not only address evolutionary questions but also obtain data useful to the wise stewardship of Hawaii's plant resources. In a project relevant to the conservation biology of native Hawaiian ferns, Dr. Thomas Ranker of the University of Hawaii will employ enzyme electrophoresis to describe levels and patterns of genetic diversity within and among populations of 24 species of native Hawaiian ferns. Levels of outcrossing and inbreeding among the tiny gametophytes of these species will be analyzed by examining natural stands of fern sporophytes as well as by sampling natural and laboratory populations of selected gametophytes. For species of the endemic genera Adenophorus and Sadleria, gametophytes will be grown in the laboratory and tested for factors affecting reproductive capacity and outcrossing behavior. Comparisons will be made between wide-ranging, common species and narrowly distributed, rare ones, and correlations sought with amounts of genetic variation and apportionment of this variation within populations or among scattered populations. These data are pertinent to management decisions regarding effective population sizes for maintaining genetic variation and overall diversity in the Hawaiian fern flora.
