In 1991 Charles Werth and Michael Windham published a model for polyploid speciation through differential silencing of duplicated genes. At the 2000 BSA meetings we proposed the allotetraploid species pair Botrychium pinnatum and B. alaskense as a possible case of two species originating through this model, i.e., differential gene silencing having produced two distinct allotetraploid species from original hybridization between the same two diploid parental species. We argued that because of unique alleles possessed by B. lunaria and B. lanceolatum, these are the only possible diploid parents of these two allotetraploid species. Despite our arguments, Dr. Werth's response was "maybe you haven't found the right parents." Charlie was right! We have since discovered, through an enzyme electrophoretic survey of Eurasian Botrychium, that 1) Eurasian B. lunaria is genetically distinct from American B. lunaria, 2) Eurasian genotypes of B. lunaria are present in the Aleutian Islands and in interior, high elevation Alaska, and 3) Eurasian B. lunaria X American B. lanceolatum is the probable parentage of B. alaskense, whereas American B. lunaria X American B. lanceolatum is the probable parentage of B. pinnatum. Further corroborating the presence of Eurasian B. lunaria in Alaska and its distinction from American B. lunaria is the discovery in Alaska of a new allotetraploid, B. yaaxudakeit, a species that appears to have been derived from hybridization between Eurasian and American genotypes of B. lunaria. Genetic divergence between Old World and New World representatives of the "same species," as evidenced through their genotypes and their allotetraploid derivatives, provides insight into limitations to spore dispersal and migration in this circumboreal genus.

Key words: allopolyploidy, Botrychium, gene silencing, polyploid speciation