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Abstract Detail


MSA - Ecology/Pathology

Hughes, Karen W. [1], Petersen, Ron [2].

What percent sequence divergence for the ribosomal ITS gene can be considered conspecific for agaric fungi from a restricted geographical region?

With improvement of techniques for extracting and amplifying DNAs from soils and other substrates, studies assessing fungal community structure are becoming increasingly common and have produced a large number of chiefly unidentified environmental sequences. Such studies have used various estimates of sequence divergence for the ribosomal ITS gene to indicate conspecificity ranging from 2% to 5% . For the most part, however, these estimates of conspecificity are not based on experimental data, and techniques for calculating sequence divergence are not given. The Great Smoky Mountains National Park (Tennessee, North Carolina) is an area that exhibits unusually high levels of heterozygosity within agaric fungi. Because typical individual basidiomata represent the product of infra-taxic matings, we assume that haplotypes from the same basidiome represent variation found within its parental biological species. Within-basidiome sequence divergence was calculated from 100 fungal fruitbodies representing 95 putative species which exhibited ITS sequence heterozygosity. For the ITS data set, selecting 0-2% ITS sequence divergence as indicating conspecificity accurately recovered 97% of paired sequences from the same basidiome. Selecting 0-3% ITS sequence divergence as indicating conspecificity accurately recovered 99% of paired sequences from the same basidiome. Based on these data, we recommend that agaric basidiomycete environmental ITS sequences which differ by no more than 2-3% be considered conspecific for purposes of estimating basidiomycete species biodiversity from restricted geographical regions. Blast searches were performed for ITS sequences in this data set using a 0-2% divergence as indicating conspecificity. Thirty-three percent matched sequences in GenBank and eight-percent of sequences matched ‘environmental samples.” It is clear that significantly more effort will be needed to enlarge the pool of named fungal ITS sequences in GenBank to aid in interpretation of environmental studies.


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1 - University of Tennessee, Knoxville, Ecology and Evolutionary Biology, 422 Hesler Biology Building, Knoxville, TN, 37996-0830, USA
2 - University of Tennessee, Ecology and Evolutionary Biology, Knoxville, TN, 37996-1100, USA

Keywords:
Fungi
species circumscription
heterozygosity.

Presentation Type: Poster:Posters for Topics
Session: P2
Location: Event Tent/Cliff Lodge
Date: Tuesday, July 28th, 2009
Time: 5:30 PM
Number: P2EP014
Abstract ID:216


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