Mycorrhizal fungi and distribution of specialized orchids

The use of a widespread fungal operational taxonomic unit in P. deformis enables a broad distribution despite high mycorrhizal specificity.
Mycorrhizal fungi and distribution of specialized orchids
Mycorrhizal fungi and distribution of specialized orchids

Specialized interactions have repeatedly evolved in the Orchidaceae, and subsequently may limit the geographic range of orchids. Davis et al. undertake a phylogenetic analysis of fungal isolates from Pheladenia deformis, an orchid with a continent-wide distribution, and find that the orchid is predominantly utilizing a single fungal operational taxonomic unit (OTU) in the genus Sebacina. The use of a widespread fungal OTU in P. deformis enables a broad distribution despite high mycorrhizal specificity. Other Sebacina OTUs utilized by different short-range endemic orchids were also found to have a continent-wide distribution, demonstrating that biogeographic patterns in orchids are likely to be driven by other factors such as edaphic requirements and pollinator-mediated limitations.

Further reading

Belinda J. Davis, Ryan D. Phillips, Magali Wright, Celeste C. Linde, Kingsley W. Dixon, 2015, 'Continent-wide distribution in mycorrhizal fungi: implications for the biogeography of specialized orchids', Annals of Botany, vol. 116, no. 3, pp. 413-421 http://dx.doi.org/10.1093/aob/mcv084