期刊
JOURNAL OF EUKARYOTIC MICROBIOLOGY
卷 58, 期 6, 页码 529-536出版社
WILEY
DOI: 10.1111/j.1550-7408.2011.00585.x
关键词
Biological species; divergence threshold; interspecific; intraspecific; morpho-species; p-distance
类别
资金
- NSERC
- Canadian Barcode of Life Network from Genome Canada through the Ontario Genomics Institute
- Mount Allison University
DNA barcoding is a tool that uses a short, standard segment of DNA to identify organisms. In diatoms, a consensus on an appropriate DNA barcode has not been reached, but several markers show promise. These include the 5.8S gene plus a fragment of the internal transcribed spacer 2 (ITS-2) of nuclear-encoded ribosomal RNA, a 420-bp segment of the 18S rRNA gene, and a 748-bp fragment at the 3'-end of the ribulose bisophosphate carboxylase large subunit (rbcL) gene. Here, we tested a 540-bp fragment 417-bp downstream of the start codon of the rbcL gene for its efficacy in distinguishing diatom species in a wide range of taxa. Overall, 381 sequences representing 66 genera and 245 species from the classes Mediophyceae and Bacillariophyceae were examined. Intra/interspecific thresholds were set at p = 0.01 differences per site (diff./site) for Mediophyceae and p = 0.02 diff./site for Bacillariophyceae and correctly segregated 96% and 93% of morphological congeners, respectively. When testing reproductively isolated or biological species, which are only available from Bacillariophyceae, 80% of species were discriminated. Therefore, we concluded that, alone, the rbcL region tested herein as potential a DNA barcode was not a sufficient discriminator of all diatoms. We suggest that this fragment could be used in a dual-locus barcode with the more variable 5.8S+ITS-2 to discriminate species without sufficient interspecific divergences in the tested rbcL region and to provide insight into species identity from a separately evolved genome.
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