Abstracts |
The Internal Transcribed Spacer (ITS) regions of ribosomal DNA are widely used as
markers for phylogenetic analyses and environmental sampling from a variety of organisms
including fungi, plants, and animals. In theory, concerted evolution homogenizes multicopy genes
so that little or no variation exists within populations or individuals. However, contrary to
theory, ITS variation has been confirmed in populations and individuals from a diverse range of
eukaryotes. The presence of intraspecific and intra-individual variation in multicopy genes has
important implications for ecological and phylogenetic studies, yet relatively little is known
about natural variation of these genes, particularly at the community level. In this study, we
examined intraspecific and intra-sporocarp ITS variation by DNA sequencing from sporocarps and
pooled roots from 68 species of ectomycorrhizal fungi collected at a single site in a Quercus
woodland. We detected ITS variation in 27 species, roughly 40% of the taxa examined. Although
intraspecific ITS variation was generally low (0.16-2.85%, mean = 0.74%), it was widespread
within this fungal community. We detected ITS variation in both sporocarps and ectomycorrhizal
roots, and variation was present within species of Ascomycota and Basidiomycota, two distantly
related lineages within the Fungi. We discuss the implications of such widespread ITS variability
with special reference to DNA-based environmental sampling from diverse fungal communities. |