GENETIC-VARIATION IN POPULATIONS OF THE ARCTIC PERENNIAL PEDICULARIS-DASYANTHA (SCROPHULARIACEAE), ON SVALBARD, NORWAY

Isozyme variability was examined in 13 geographically isolated populat ions of the endemic arctic hairy lousewort (Pedicularis dasyantha) in the Svalbard Archipelago, 80 degrees N latitude, Norway. Of the 23 enz yme systems screened on five buffer systems 18 were interpretable. Of the 31 reliable loci, only 6-phosphogluconate dehydrogenase (6-Pgd), w as polymorphic. However, no heterozygotes were detected. Frequencies f or allele 1 among the populations varied from 1.00 in the north to 0.0 0 in the south and 0.53 in the central ''overlap'' region. At the spec ies level the mean number of alleles per locus (A) was 1.03. Percentag e of polymorphic loci (P) was 3%. Expected heterozygosity (H-e) was 0. 016. At the population level the mean number of alleles per locus was 1.01, and 1.1% of the loci were polymorphic. H-e was 0.004. These valu es are low compared to endemic, widespread, selfing, and outcrossed sp ecies. Flower color morphs were distinct. They varied within and among the 13 populations. The frequency of color morphs coincided with alle le frequencies of 6-PGD: allele 1 was found in dark purple morphs, and allele 2 was found in light morphs. This species shows more isozyme g enetic variability than the five other species reported in the genus b ut generally less Variation than other species with limited regional d istributions. Low-level genetic variation in this diploid species may be a result of colonization events coupled with genetic drift, founder effects, and strong natural selection. Additional factors include the self-compatible reproductive system and the long-lived perennial habi t.