VANDERPOOL, STARIA S.* and LINH V. HOANG. Department of Biological Sciences, Arkansas State University, State University, AR 72467-0599. - Genetic variation among populations of Solidago riddellii (Asteraceae): an uncommon species with a wide range.
Solidago riddellii Frank is an outcrossing, clonal, herbaceous
perennial species with a localized but widespread distribution. It
occurs in fens and wet meadows with a global range from northern
Arkansas through the upper Midwest with eastern extensions into
Ontario and western populations known from southern Manitoba. Genetic
variation within and among populations of Solidago riddellii
was assessed using allozyme polymorphism to investigate the
consequences of rapid migration of plant species on population genetic
structure. Modern distribution is inferred as the result of
colonization northward following retreat of glaciers in the upper
Midwest and the fragmentation of wetland habitat by modern land use
patterns. A total of 416 individuals from 30 populations collected
from 10 states and 2 Canadian provinces was characterized using enzyme
electrophoresis. Estimation of population level genetic variation was
accomplished using standard methods. Total genetic variability is
consistent with that of other species with similar life history
characteristics. Mean identity was 0.93, with identity values for
regions ranging from 0.97 to 0.91 (south, including Arkansas and
Missouri populations). UPGMA cluster analysis using genetic identity
revealed 5 clusters. Cluster 1 includes 2 eastern populations (Ohio,
Illinois), Missouri and Arkansas populations. Cluster 2 includes 9
eastern populations, 1 western population (Wisconsin) and 1 Missouri
population. Cluster 3 includes 3 eastern populations, 8 western
populations, and 1 Arkansas population. Cluster 4 consisted of a
single, anomalous population in Missouri, and Cluster 5 a single
Minnesota population. No strong pattern of genetic differentiation
between geographic regions, or distribution of genetic variability was
seen although weak regional patterns could be developed.
Key words: genetic variation of rare taxa, Solidago