Amplified fragment length polymorphism in Elymus elymoides, Elymus multisetus, and other Elymus taxa

The geographic and phylogenetic significance of amplified fragment length polymorphism within and among 22 Elymus elymoides (Raf.) Swezey subsp. elymoides, 24 E. elymoides subsp. brevifolius (J.G. Sm.) Barkworth, and 13 Elymus multisetus (J.G. Sm.) Burtt-Davy squirreltail accessions was assessed relative to six other North American and three Eurasian Elymus taxa. Elymus elymoides and E. multisetus, comprising Elymus sect. Sitanion (Raf.) A. Love, were both monophyletic and closely related compared with other congeners. The monophyly of subsp. elymoides was also supported; subsp. brevifolius, however, was paraphyletic and separated into four genetically distinct groups. Estimates of nucleotide divergence among the five E. elymoides groups range from 0.0194 to 0.0288, with approximately 0.0329 differences per site between E. elymoides and E. multisetus. Corresponding estimates of nucleotide divergence range from 0.0243 to 0.0387 among North American taxa and from 0.0337 to 0.0455 between North American and Eurasian taxa. DNA polymorphism among E. elymoides accessions was correlated with geographic provenance and previously reported quantitative traits. Distinct genetic groups of E. elymoides generally correspond to different geographic regions, whereas divergent E. multisetus and E. elymoides accessions are sympatric. Thus, taxonomic ranks of E. multisetus and E. elymoides were supported and geographic groups within E. elymoides were distinguished.