Another week that begins with some interesting reads. I find it fascinating that every week I am able to find a good number of academic publications which use DNA-based identifications and/or DNA barcoding in particular. The field is now large enough and gained sufficient momentum that new discoveries and findings appear on a more or less daily basis. As a result every week I am in the fortunate situation to pick a few of many publications to highlight in the Monday reads:
Until now, the potential of NGS for the construction of barcode libraries or integrative taxonomy has been seldom realised. Here, we amplified (two-step PCR) and simultaneously sequenced (MiSeq) multiple markers from hundreds of fig wasp specimens. We also developed a workflow for quality control of the data. Illumina and Sanger sequences accumulated in the past years were compared. Interestingly, primers and PCR conditions used for the Sanger approach did not require optimisation to construct the MiSeq library. After quality controls, 87% of the species (76% of the specimens) had a valid MiSeq sequence for each marker. Importantly, major clusters did not always correspond to the targeted loci. Nine specimens exhibited two divergent sequences (up to 10%). In 95% of the species, MiSeq and Sanger sequences obtained from the same sampling were similar. For the remaining 5%, species were paraphyletic or the sequences clustered into divergent groups on the Sanger + MiSeq trees (>7%). These problematic cases may represent coding NUMTS or heteroplasms. Our results illustrate that Illumina approaches are not artefact-free and confirm that Sanger databases can contain non-target genes. This highlights the importance of quality controls, working with taxonomists and using multiple markers for DNA-taxonomy or species diversity assessment.
DNA barcoding the bees (Hymenoptera: Apoidea) of Chile: species discovery in a reasonably well known bee fauna with the description of a new species of Lonchopria (Colletidae)
We compare the diversity of Chilean bees as understood from traditional taxonomy-based catalogues with that currently known from DNA barcodes using the BIN system informed by ongoing morphology-based taxonomy. While DNA barcode surveys of the Chilean bee fauna remain incomplete; it is clear that new species can readily be distinguished using this method and that morphological differentiation of distinct barcode clusters is sometimes very easy. We assess the situation in two genera in detail. In Lonchopria Vachal one "species" is readily separable into two BINs that are easily differentiated based upon male mandibular and genitalic morphology (characters generally used in this group) as well female hair patterns. Consequently, we describe Lonchopria (Lonchopria) heberti Packer and Ruz, new species. For Liphanthus Reed, a large number of new species has been detected using DNA barcoding and considerable additional traditional morphological work will be required to describe them. When we add the number of BINs (whether identified to named species or not) to the number of Chilean bee species that we know have not been barcoded (both described and new species under study in our laboratories) we conclude that the bee fauna of Chile is substantially greater than the 436 species currently known.
Forensic application of DNA barcoding for identification of illegally traded African pangolin scales
The escalating growth in illegal wildlife trade and anthropogenic habitat changes threaten the survival of pangolin species worldwide. All eight extant species have experienced drastic population size reductions globally with a high extinction risk in Asia. Consequently, forensic services have become critical for law enforcement, with a need for standardised and validated genetic methods for reliable identifications. The seizure of three tonnes of pangolin scales, believed to have originated from Africa, by Hong Kong Customs Authorities provided an opportunity for the application of DNA barcoding in identifying scales. Three mitochondrial DNA gene regions (COI, Cyt b, and D-loop) were amplified for a subsample of the confiscated material and compared with taxonomically verified references. All four African species were recovered as monophyletic with high interspecific uncorrected p-distance estimates (0.048-0.188) among genes. However, only three of four African species (Phataginus tricuspis, Phataginus tetradactyla, and Smutsia gigantea, originating from West and Central Africa) and one of four Asian species (Manis javanica from Southeast Asia) were identified among scales. Although the assignment of unknown scales to specific species was reliable, additional genetic tools and representative reference material are required to determine geographic origins of confiscated pangolin specimens.
Kampo is the general designation for traditional Japanese herbal medicines, which are recognized as official medicines and listed in the Japanese pharmacopoeia (JP). In most cases, it is difficult to identify the crude drug materials to species level using only traditional identification methods. We report the first online DNA barcode identification system, which includes standard barcode sequences from approximately 95% of the species recorded in the JP (16th edition). This tool provides users with basic information on each crude drug recorded in the JP, DNA barcoding identification of herbal material, and the standard operating procedure (SOP) from sampling to data analysis. ITS2 sequences (psbA-trnH was an alternative when ITS2 could not be amplified) were generated from a total of 576 samples to establish the database. An additional 100 samples (from different medicinal parts, from both single origin and multiple origins and from both retailers and the planting base) were identified using the system. A total of 78% of the test samples were identified as the species listed on their label. This system establishes a model platform for other pharmacopeias from countries like China, Korea, the US and the European Union, for the safe and effective utilization of traditional herbal medicines.