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Fungal host utilization helps circumscribe leafless Coralroot orchid species: An integrative analysis of Corallorhiza odontorhiza and C. wisteriana
Author(s) -
Freudenstein John V.,
Barrett Craig F.
Publication year - 2014
Publication title -
taxon
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 81
eISSN - 1996-8175
pISSN - 0040-0262
DOI - 10.12705/634.3
Subject(s) - biology , orchidaceae , phylogenetic tree , plastid , taxon , botany , host (biology) , population , evolutionary biology , genus , ecology , genetics , demography , chloroplast , sociology , gene
The leafless parasitic habit has arisen numerous times in Orchidaceae and characterizes the small temperate genus Corallorhiza . Because of their reduced morphology, parasitic plants have been some of the most difficult to delimit at the species level and to place phylogenetically and thus are a likely place to find cryptic species. In such cases molecular data and the presence of associated species are particularly helpful for circumscribing such taxa. Two long–recognized North American species are the focus of this study, in which the specificity and relationships of the associated fungi are examined. Phylogenetic analysis of sequences of plastid loci rpl32 and trnLF from C. odontorhiza and C. wisteriana and the ITS region from their associated fungi in Thelephoraceae and Russulaceae was undertaken and related to floral morphology, as examined via principal components analysis, and geographic origin of accessions. Corallorhiza wisteriana and C. odontorhiza are distinct based on plastid DNA, although they utilize overlapping sets of fungi. Eastern and western population groups of C. wisteriana are also distinct for plastid DNA and surprisingly utilize different fungal families, Russulaceae and Thelephoraceae, respectively. They are also subtly distinct morphologically. Polymorphism for fungal family utilization was detected in three orchid populations and fungal specificity was shown to be narrower for Russulaceae than for Thelephoraceae. Two cryptic species are distinguished within C. wisteriana based on fungal usage, plastid DNA, morphology and geography. Two host shifts are hypothesized to have occurred within polymorphic populations of C. wisteriana . Fungal specificity is related to trophic strategy and recency of colonization by the orchid.