XVI International Botanical Congess

Examination of isozyme diversity within and among populations of Hymenoxys herbacea (E. L. Greene) Cusick = H. acaulis var. glabra (lakeside daisy) a Great Lakes endemic. Hymenoxys acaulis var. glabra, commonly known as lakeside daisy, is an endangered Great Lakes endemic found in four isolated sites in Ohio, Michigan, and Ontario, Canada. The purpose of this study was to determine the levels and apportionment of diversity within and among the sites utilizing isozyme markers. A total of 18 loci and 8 enzymes were resolved. Total species diversity (Ht =0.126), and mean diversity within populations (Hs = 0.087) are slightly lower than the mean for other outcrossing endemic species. By contrast, the proportion of total diversity among populations (Gst = 0.232) is 30% higher than the average for other outcrossing endemics. Lakeside daisy contains more allozyme diversity than many endangered species and is only slightly depressed compared to outcrossing endemics. Different allelic frequencies in extant populations (the basis of the higher Gst values) may have been generated by chance during the fragmentation of larger populations and/or decreases in populaton sizes.