Relationship among Collybia s. str. in Greenland, North America and Eurasia

Abstract

Collections of Collybia s. str. from Greenland were analyzed morphologically and by DNA sequencing of the nuclear ribosomal ITS1-5.8S-ITS2 region. Results confirmed that all three species of Collybia were present and sympatric in Greenland. Collybia tuberosa ITS sequences of collections from Greenland, Europe and North America were remarkably similar, with only one variable base and 3 apomorphies among ten geographically divergent collections. Two collections from Greenland differed with respect to the variable base. Nine collections of C. cookei were sequenced, including one from Greenland. Collections from North America and Greenland formed a well-supported clade, but two unique apomorphies were present in the Greenland collection.

Twelve collections of Collybia cirrata from Europe and North America were also nearly identical but Greenland collections showed a number of unique apomorphies. Discovery of divergent genotypes in Greenland not detected in either North America or Eurasia may be a consequence of founder effects in Greenland populations - mutation and genetic drift in small isolated populations followed by range expansion.