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DNA Barcoding to Improve the Taxonomy of the Afrotropical Hoverflies (Insecta: Diptera: Syrphidae).

Jordaens K, Goergen G, Virgilio M, Backeljau T, Vokaer A, De Meyer M - PLoS ONE (2015)

Bottom Line: Nine species pairs showed a low (< 0.03) mean interspecific K2P distance that resulted in several incorrect identifications.Optimal K2P thresholds to differentiate intra- from interspecific K2P divergence were highly different among the three subfamilies (Eristalinae: 0.037, Syrphinae: 0.06, Microdontinae: 0.007-0.02), and among the different general suggesting that optimal thresholds are better defined at the genus level.In addition to providing an alternative identification tool, our study indicates that DNA barcoding improves the taxonomy of Afrotropical hoverflies by selecting (groups of) taxa that deserve further taxonomic study, and by attributing the unknown sex to species for which only one of the sexes is known.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology-Invertebrate Section and Joint Experimental Molecular Unit (JEMU), Royal Museum for Central Africa, Leuvensesteenweg 13, B-3080 Tervuren, Belgium.

ABSTRACT
The identification of Afrotropical hoverflies is very difficult because of limited recent taxonomic revisions and the lack of comprehensive identification keys. In order to assist in their identification, and to improve the taxonomy of this group, we constructed a reference dataset of 513 COI barcodes of 90 of the more common nominal species from Ghana, Togo, Benin and Nigeria (W Africa) and added ten publically available COI barcodes from nine nominal Afrotropical species to this (total: 523 COI barcodes; 98 nominal species; 26 genera). The identification accuracy of this dataset was evaluated with three methods (K2P distance-based, Neighbor-Joining (NJ) / Maximum Likelihood (ML) analysis, and using SpeciesIdentifier). Results of the three methods were highly congruent and showed a high identification success. Nine species pairs showed a low (< 0.03) mean interspecific K2P distance that resulted in several incorrect identifications. A high (> 0.03) maximum intraspecific K2P distance was observed in eight species and barcodes of these species not always formed single clusters in the NJ / ML analayses which may indicate the occurrence of cryptic species. Optimal K2P thresholds to differentiate intra- from interspecific K2P divergence were highly different among the three subfamilies (Eristalinae: 0.037, Syrphinae: 0.06, Microdontinae: 0.007-0.02), and among the different general suggesting that optimal thresholds are better defined at the genus level. In addition to providing an alternative identification tool, our study indicates that DNA barcoding improves the taxonomy of Afrotropical hoverflies by selecting (groups of) taxa that deserve further taxonomic study, and by attributing the unknown sex to species for which only one of the sexes is known.

No MeSH data available.


Frequency histogram of congeneric (open bars) and intraspecific (filled bars) Kimura 2-parameter (K2P) distances within three Central Afrotropical hoverfly subfamilies, based on COI barcodes.
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pone.0140264.g004: Frequency histogram of congeneric (open bars) and intraspecific (filled bars) Kimura 2-parameter (K2P) distances within three Central Afrotropical hoverfly subfamilies, based on COI barcodes.

Mentions: The BM and BCM analyses were performed on 66 nominal species for which more than one barcode was available (Table 2; S3 Table). The best threshold distance to separate intra- from interspecific K2P distances was 0.057 for the entire dataset but with large differences in thresholds among the three subfamilies, viz. 0.037 (Eristalinae), 0.060 (Syrphinae), and 0.007–0.02 (Microdontinae) (Fig 4). Only for the Microdontinae there was a true barcode gap with no overlap between the frequency histograms of congeneric (minimal K2P distance: 0.02) and intraspecific (maximal K2P distance: 0.007) K2P distances. For all genera with >5 morphospecies, there was a true barcoding gap (subfamily Eristalinae: Eristalinus: 0.040–0.050, Eumerus: 0.011–0.099, Mesembrius: 0.017–0.040, Phytomia: 0.052–0.098, Syritta: 0.043; subfamily Syrphinae: Paragus: 0.013–0.067; subfamily Microdontinae: Metadon: 0.007–0.020), except for the genus Allobaccha (subfamily Syrphinae: optimal threshold: 0.053).


DNA Barcoding to Improve the Taxonomy of the Afrotropical Hoverflies (Insecta: Diptera: Syrphidae).

Jordaens K, Goergen G, Virgilio M, Backeljau T, Vokaer A, De Meyer M - PLoS ONE (2015)

Frequency histogram of congeneric (open bars) and intraspecific (filled bars) Kimura 2-parameter (K2P) distances within three Central Afrotropical hoverfly subfamilies, based on COI barcodes.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608823&req=5

pone.0140264.g004: Frequency histogram of congeneric (open bars) and intraspecific (filled bars) Kimura 2-parameter (K2P) distances within three Central Afrotropical hoverfly subfamilies, based on COI barcodes.
Mentions: The BM and BCM analyses were performed on 66 nominal species for which more than one barcode was available (Table 2; S3 Table). The best threshold distance to separate intra- from interspecific K2P distances was 0.057 for the entire dataset but with large differences in thresholds among the three subfamilies, viz. 0.037 (Eristalinae), 0.060 (Syrphinae), and 0.007–0.02 (Microdontinae) (Fig 4). Only for the Microdontinae there was a true barcode gap with no overlap between the frequency histograms of congeneric (minimal K2P distance: 0.02) and intraspecific (maximal K2P distance: 0.007) K2P distances. For all genera with >5 morphospecies, there was a true barcoding gap (subfamily Eristalinae: Eristalinus: 0.040–0.050, Eumerus: 0.011–0.099, Mesembrius: 0.017–0.040, Phytomia: 0.052–0.098, Syritta: 0.043; subfamily Syrphinae: Paragus: 0.013–0.067; subfamily Microdontinae: Metadon: 0.007–0.020), except for the genus Allobaccha (subfamily Syrphinae: optimal threshold: 0.053).

Bottom Line: Nine species pairs showed a low (< 0.03) mean interspecific K2P distance that resulted in several incorrect identifications.Optimal K2P thresholds to differentiate intra- from interspecific K2P divergence were highly different among the three subfamilies (Eristalinae: 0.037, Syrphinae: 0.06, Microdontinae: 0.007-0.02), and among the different general suggesting that optimal thresholds are better defined at the genus level.In addition to providing an alternative identification tool, our study indicates that DNA barcoding improves the taxonomy of Afrotropical hoverflies by selecting (groups of) taxa that deserve further taxonomic study, and by attributing the unknown sex to species for which only one of the sexes is known.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology-Invertebrate Section and Joint Experimental Molecular Unit (JEMU), Royal Museum for Central Africa, Leuvensesteenweg 13, B-3080 Tervuren, Belgium.

ABSTRACT
The identification of Afrotropical hoverflies is very difficult because of limited recent taxonomic revisions and the lack of comprehensive identification keys. In order to assist in their identification, and to improve the taxonomy of this group, we constructed a reference dataset of 513 COI barcodes of 90 of the more common nominal species from Ghana, Togo, Benin and Nigeria (W Africa) and added ten publically available COI barcodes from nine nominal Afrotropical species to this (total: 523 COI barcodes; 98 nominal species; 26 genera). The identification accuracy of this dataset was evaluated with three methods (K2P distance-based, Neighbor-Joining (NJ) / Maximum Likelihood (ML) analysis, and using SpeciesIdentifier). Results of the three methods were highly congruent and showed a high identification success. Nine species pairs showed a low (< 0.03) mean interspecific K2P distance that resulted in several incorrect identifications. A high (> 0.03) maximum intraspecific K2P distance was observed in eight species and barcodes of these species not always formed single clusters in the NJ / ML analayses which may indicate the occurrence of cryptic species. Optimal K2P thresholds to differentiate intra- from interspecific K2P divergence were highly different among the three subfamilies (Eristalinae: 0.037, Syrphinae: 0.06, Microdontinae: 0.007-0.02), and among the different general suggesting that optimal thresholds are better defined at the genus level. In addition to providing an alternative identification tool, our study indicates that DNA barcoding improves the taxonomy of Afrotropical hoverflies by selecting (groups of) taxa that deserve further taxonomic study, and by attributing the unknown sex to species for which only one of the sexes is known.

No MeSH data available.