GENE FLOW IN LICHENS

Experimental studies of the evolutionary biology of lichen fungi have been hampered by massive difficulties of in vitro culture and artificial crosses are still not possible. Gene flow in these organisms is demonstrated here for the first time by the analysis of secondary products in the progeny of individuals from natural populations of mixed chemotypes of the Cladonia chlorophaea complex. All of the chemotypes in this study have been interpreted as distinct sibling species. In the Appalachian Mountains of North Carolina, however, the grayi and merochlorophaea chemotypes are found to belong to a single interbreeding populations that is reproductively isolated from the cryptochlorophaea chemotype. In the Coastal Plain, the cryptochlorophaea chemotype hybridizes with the local endemic perlomera chemotype. This study has major impact for species concept in lichens because consideration of neither morphologial tendencies nor biogenetic relationships of the secondary products could have predicted its result.