Patterns of allozyme variation and clonal diversity in Carex lasiocarpa and C. pellita (Cyperaceae)

We compared genetic variability and clonal diversity in the closely related sedges Carex lasiocarpa and C. pellita using allozyme markers at 12 loci. Both species produce spreading rhizomes, occur in open habitats, and can form large clones; C. lasiocarpa primarily along lakeshores, or in bogs, fens, or marshes, and C. pellita more commonly along riverbanks and ditches or in wet meadows. Polymorphism was high in both species, similar to that of other rhizomatous Carex and to other species with comparable growth forms and life histories. Total gene diversity was higher for C. lasiocarpa (H_T = 0.266) than for C. pellita (H_T = 0.248), but the coefficient of differentiation among populations was lower. Rare alleles usually occurred as heterozygotes rather than homozygotes, and significant deviations from Hardy-Weinberg equilibrium were found at few loci, suggesting that both species are predominantly outcrossing. Mean clone size, diversity, and evenness were not significantly different between the two species, although populations varied from monoclonal to those where nearly every sampled shoot belonged to a different clone. No significant differences in genetic variation or clone size of C. pellita were found when comparisons were made between groups based on climate (warmer vs. cooler) or successional stage (pioneer vs. established). However, within C. lasiocarpa, genetic variability decreased and clone size increased in cooler climates and at established sites.