Intersterility groups in Collybia subnuda

Abstract

Two intersterility groups occur within Collybia subnuda. The two intersterility groups retain a low level of intercompatibility in vitro. They are similar morphologically and have nearly identical intergenic transcribed spacer rDNA sequences. Intersterility group 1 is usually found on oak leaf litter, while intersterility group 2 is usually found associated with oak wood. Collection records and the results of intercollection pairing among single-spore isolates indicate that the two intersterility groups are sympatric throughout the Appalachian Mountains and into New York. Both intersterility groups produce binucleate basidiospores in low frequency, and thus have the potential for secondary homothallism. A mechanism for sympatric evolution of heterothallic Basidiomycetes is proposed, but neither a sympatric nor allopatric origin for the C. subnuda ISGs is advocated.

Key Words:

• Agaricales
• allopatry
• rDNA ITS sequence
• sympatry