Isozyme variation and its environmental correlates in Elymus glaucus from the California Floristic Province

Genetic variation in the self-fertile, allotetraploid grass Elymus glaucus Buckley was assessed using isozymes in 133 populations from southwestern Oregon and from the San Francisco Bay area and central Sierra Nevada mountains in California. Elymus glaucus was highly (98.5%) homozygous but also highly variable; 77% of loci were polymorphic, and the mean number of alleles per locus was 2.96. Populations were highly differentiated, with 40% of variation among populations. Geographic and genetic distances among populations were not correlated, except that populations collected within 5 km were generally more similar than average. Genetic distance among populations could not be predicted from geographic distance, geographic location, foliage pubescence, serpentine substrate, or habitat moisture. However, two genetic clusters, associated with elevation, did emerge. The taxonomic status of Elymus glaucus ssp. jepsonii (Burtt Davy) Gould, based on leaf pubescence, was not supported.Key words: Elymus glaucus, iso...