Shefferson et al 2007

		Shefferson, R.P., D.L. Taylor, M. Weiss, S. Garnica, M.K. McCormick, S. Adams,
		H.M. Gray, J.W. McFarland, T. Kull, K. Tali, T. Yukawa, T. Kawahara, K. Miyoshi, and Y.-I. Lee. 2007. The evolutionary history of mycorrhizal specificity among lady's slipper orchids. Evolution 61:1380-1390.

Abstract Although coevolution is acknowledged to occur in nature, coevolutionary
patterns in symbioses not involving species-to-species relationships are poorly
understood. Mycorrhizal plants are thought to be too generalist to coevolve with their
symbiotic fungi; yet some plants, including some orchids, exhibit strikingly narrow
mycorrhizal specificity. Here, we assess the evolutionary history of mycorrhizal
specificity in the lady’s slipper orchid genus, Cypripedium. We sampled 90
populations of 15 taxa across three continents, using DNA methods to identify fungal
symbionts and quantify mycorrhizal specificity. We assessed phylogenetic
relationships among sampled Cypripedium taxa, onto which we mapped mycorrhizal
specificity. Cypripedium taxa associated almost exclusively with fungi within family
Tulasnellaceae. Ancestral specificity appears to have been narrow, followed by a
broadening after the divergence of C. debile. Specificity then narrowed, resulting in
strikingly narrow specificity in most of the taxa in this study, with no taxon re-widening
to the same extant as basal members of the genus. Sympatric taxa generally
associated with different sets of fungi, and most clades of Cypripedium-mycorrhizal
fungi were found throughout much of the Northern Hemisphere, suggesting that these
evolutionary patterns in specificity are not the result of biogeographic lack of
opportunity to associate with potential partners. Mycorrhizal specificity in genus
Cypripedium appears to be an evolvable trait, and associations with particular fungi
are phylogenetically conserved.

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View data (FASTA files):
Fungal ITS alignment
Fungal mtLSU alignment
Plant rbcL alignment
Plant ITS alignment

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Shefferson et al. 2007