ECOLOGICAL GENETICS OF NORWEGIAN DAPHNIA .3. CLONAL RICHNESS IN AN ARCTIC APOMICTIC COMPLEX

Arctic pond populations of Daphnia pulex on Svalbard, off the north No rwegian coast, were assayed for clonal richness. A total of 21 unique clones from 20 ponds were distinguished by allozyme electrophoresis at seven enzyme loci. Seventeen clones showed unbalanced electromorph ba nding patterns at certain enzyme loci, which suggests that they are po lyploids. Each pond harboured an average of 1.7 clones (range 1-4). Th e most common clone was found in six ponds, and accounted for 23.5 per cent of all animals screened. Most clones were found only in one or t wo ponds. No discernible geographical patterns could be detected in cl onal distributions, and all sampled areas held unique clones. The data suggest that our sampling effort has uncovered only a small subset of a much larger array of clones on this remote arctic archipelago, and indicates that the genetic structure of this apomictic complex is one of the most fragmented among asexual organisms.