CLONAL STRUCTURE AND FERTILITY IN A SYMPATRIC POPULATION OF THE PEAT MOSSES SPHAGNUM-RUBELLUM AND SPHAGNUM-CAPILLIFOLIUM

Data from isozyme and leaf shape variation are combined to explore the clonal structure at a site where hybridization between Sphagnum rubel lum and Sphagnum capillifolium was previously indicated. Shoots of bot h species were sampled at 10-cm intervals along seven transects across different hummocks. Allelic data from 13 enzyme systems revealed 22 m ultilocus genotypes representing different clones, 18 being S. capilli folium and 4 being S. rubellum. The mean +/- SE and maximum clonal len gth were 35 +/- 8 cm and 160 cm, respectively. The sets of alleles fou nd in the progeny of S. capillifolium were identical to the maternal c omplement of alleles in 78% of the material, indicating either self-fe rtilization or fertilization by a male with the same set of alleles at the screened loci. Outcrossing was detected in six cases. Patterns of differentiation and the hierarchical structuring of diversity among s pecies, transects, and clones were analysed with canonical variates an alysis using stem-leaf characters. A stronger relative differentiation was found between transects than between species. Clones identified b y electrophoresis were usually morphologically well defined. Hybridiza tion was indicated by morphological characters, occasional misplaced a lleles, and signs of developmental instability.