Secondary Metabolites as a Tool in Ascomycete Systematics: Lichenized Fungi
For many years, the secondary products called lichen substances have been intimately involved in the systematics of the lichen-forming ascomycetes. Today they take on a new importance as markers in genetic studies and for the analysis of gene flow and reproductive isolation. Lichen systematics has been much hampered in that artificial crosses are not possible. Refined methods of thin-layer chromatography and high-performance liquid chromatography now make it possible to chemotype single-spore cultures grown in vitro and consequently to analyze the progeny of maternal individuals from nature. Since lichen fungi are haploid, the appearance of a progeny chemotype different from the maternal one can detect and identify the source of gene flow. Examples from the Cladonia chlorophaea and Ramalina siliquosa species complexes are used to demonstrate this approach to the analysis of gene exchange in lichen fungi.
KeywordsGene Flow Reproductive Isolation Hybrid Zone Usnic Acid Southern Appalachian Mountain
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