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Evolution of lichen symbioses

Lutzoni et al. studied the evolution of lichen symbioses, using a dataset of nuclear large and small subunit rDNA sequences from 56 Ascomycota

Phylogenetic trees were inferred, and switches between lichenized and free-living lifestyles were mapped onto the phylogeny using maximum likelihood methods

Results suggest that there may have been only a single origin of lichenization in the Ascomycota, but that there have been several reversals

Lutzoni et al’s results contradict those of an ealrier study by Gargas et al., which suggested several independent origins of lichenization in the Ascomycota, and no reversals

The conflict among these studies reflects the difficulty of reconstructing patterns of evolution using phylogenetic trees—incomplete or biased sampling is a source of error, but even with complete and correct trees, it can be difficult to “map” characters onto a phylogeny


Gargas, A., P. T. DePriest, M. Grube, and A. Tehler. 1995. Multiple origins of lichen symbiosis suggested by ssu rDNA phylogeny. Science 268: 1492-1495.

Lutzoni, F., M. Pagel, and V. Reeb. 2001. Major fungal lineages are derived from lichen symbiotic ancestors. Nature 411:937-940.

All content © 2005 AFTOL (Assembling the Fungal Tree of Life Project). Website managed by Jason Slot. AFTOL logo designed by Michal Skakuj. Contact Dr. David Hibbett with any questions. This page was last modified on 08/31/05. Development of this site is being supported by a grant from the National Science Foundation for research in fungal evolutionary biology (NSF award number DEB-0228657).