Genetic variation and differentiation in Nordic populations of Elymus alaskanus (Scrib. ex Merr.) Love (Poaceae)

To gain information on the extent and nature of genetic variation in Elymus alaskanus, levels and distribution of genetic variation were assessed with in and among 13 populations originating from Iceland, Norway, Sweden and Ru ssia using allozymes. The results showed that four (30.7%) of the 13 loci w ere polymorphic within the species, while the mean percentage of polymorphi c loci within the populations was 1.9%. The mean number of alleles per locu s for the species was 1.8 and 1.02 across the populations. Genetic diversit y at the species level was low (H-es = 0.135), and mean population diversit y was notably lower (H-ep = 0.005). A high degree of genetic differentiatio n was observed among populations. The salient points emerging from this stu dy are: (1) statistically significant differences were found in allele freq uencies among populations for every polymorphic locus (P < 0.001), (2) the high mean coefficient of gene differentiation (G(ST)) showed that 95% of th e total allozyme variation was attributable to differences among population s, and (3) relatively high genetic distances between the populations were o btained (mean D = 0.16). The Norwegian populations had the highest genetic diversity as compared with the other populations. Geographical comparisons revealed three different groups of populations clearly differentiated, i.e. Scandinavia (Norway and Sweden), Iceland and Russia. Cluster and principal coordinates analyses revealed the same genetic patterns of relationships a mong populations. Generally, this study indicates that E, alaskanus contain s low allozymic variation in its populations. The implications of these res ults for the conservation of the species are discussed.