Patterns and levels of genetic differentiation in North American populations of the Alaskan wheatgrass complex

Levels and distribution of genetic variation were assessed using six allozy mes in 27 populations of Alaskan wheatgrass (Elymus alaskanus) from differe nt locations in Canada, USA, Greenland and Russia to obtain information on the genetic structure of these populations. The enzyme systems were AGO, DI A, GPI, MDH, PGM and SKD. Allozyme variation at the species level was high, with 64.3% (Ps) of the loci being polymorphic, an average number of allele s per locus of 1.9 (As), and an average genetic diversity of 0.17 (Hes). Di fferentiation was found in the populations studied, with the following find ings: (1) statistically significant differences were found in allele freque ncies among populations for every polymorphic locus (P < 0.001); (2) 63% of the total allozyme variation at polymorphic loci was partitioned among pop ulations (G(ST) = 0.63); (3) relatively low mean genetic distances between the populations were obtained (mean D = 0.029); (4) the genetic structure o f Russian populations are clearly distinct from the other populations, the cluster and principal component analyses revealed the same genetic patterns of relationships among populations. This study also indicates that E, alas kanus contains different levels of allozyme variation in its populations. F urthermore, some banding patterns at the loci Aco-1, Aco-2, Gpi-2, Mdh-1, S kd-1, Skd-2 can be used as markers to identify individual populations.