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

Abstract

Levels and distribution of genetic variation were assessed using six allozymes in 27 populations of Alaskan wheatgrass (Elymus alaskanus) from different locations in Canada, USA, Greenland and Russia to obtain information on the genetic structure of these populations. The enzyme systems were ACO, DIA, 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 alleles per locus of 1.9 (As), and an average genetic diversity of 0.17 (Hes). Differentiation was found in the populations studied, with the following findings: (1) statistically significant differences were found in allele frequencies among populations for every polymorphic locus (P < 0.001); (2) 63% of the total allozyme variation at polymorphic loci was partitioned among populations (GST = 0.63); (3) relatively low mean genetic distances between the populations were obtained (mean D = 0.029); (4) the genetic structure of 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. alaskanus contains different levels of allozyme variation in its populations. Furthermore, some banding patterns at the loci Aco-1, Aco-2, Gpi-2, Mdh-1, Skd-1, Skd-2 can be used as markers to identify individual populations.