Allozymic uniformity in Iris lacustris (dwarf lake iris) in Wisconsin

Iris lacustris Nutt. is a federally listed threatened species in Canada and the United States and is currently under consideration for active conservation management. The species is restricted to the shores of the western Great Lakes region and to a very narrow habitat type. Reproduction is almost exclusively by vegetative ramets. Limited sexual reproduction occurs after primarily geitonogamous pollination, although the plant is primarily selfed. Enzyme electrophoresis was used to determine the extent of genetic variation within and between Wisconsin populations. Ten enzymes coded by 22 putative genetic loci were examined. All nine populations were found to be monomorphic at the 22 loci for the same suite of isozymes. Heterozygosity was not detected at any loci. The apparent genetically depauperate nature of the species is addressed with regard to life history and reproductive biology. Implications for conservation management are addressed.