Levels and distribution of genetic variation were assessed using allozymes
in 54 populations of Elymus caninus from different locations in Denmark, Fi
nland, Iceland, Italy, Norway, Sweden, Russia, China and Pakistan in order
to obtain information on the extent and nature of genetic variation in this
caespitose, predominantly self-fertilising, allotetraploid and perennial g
rass species. Allozyme variation at the species level was high, with 71.4%
of the loci being polymorphic, an average number of alleles per locus of 2.
2, and an average genetic diversity of 0.23. All 54 populations showed some
level of polymorphism, which varied substantially from population to popul
ation. A high degree of population differentiation was found, with the foll
owing remarkable findings: (1) statistically significant differences were f
ound in allele frequencies among populations for every polymorphic locus (P
< 0.001), (2) 62% of the total allozyme Variation at polymorphic loci was
partitioned among populations (G(ST) = 0.62), and (3) relatively high genet
ic distances between the populations were obtained (mean D = 0.16). Genetic
structuring was evident among populations from different geographical area
s. The Nordic populations showed the highest levels of genetic variation. C
luster and principal component analyses revealed the same genetic patterns
of relationships among populations. Generally, this study indicates that E.
caninus contains a high level of allozymic variation in its populations.