Tuesday, October 15, 2013

Grass miner moths

Rapid development of broad regional and international DNA barcode libraries have brought new insights into the species diversity of many areas and groups. Many new species, even within well-investigated species groups, have been discovered based initially on differences in DNA barcodes. We barcoded 437 collection specimens belonging to 40 pre-identified Palearctic species of the Elachista bifasciella group of moths (Lepidoptera, Elachistidae). Although the study group has been a subject of several careful morphological taxonomic examinations, an unexpectedly high number of previously undetected putative species is revealed, resulting in a 34% rise in species number in the study area. The validity of putative new species was subsequently supported with diagnostic morphological traits. We show that DNA barcodes provide a powerful method of detecting potential new species even in taxonomic groups and geographic areas that have previously been under considerable morphological taxonomic scrutiny.

This abstract is from a new study by Finnish researchers recently published in Nature Scientific Reports. They targeted Palearctic members of Elachista bifasciella group. The moth genus Elachista comprises some 700 species in total, 130 of which belong to the group studied. All have one thing in common - they are difficult to identify as they are small, uniformly colored, with only minute morphological differences. However, they have been subjected to thorough morphology-based taxonomic investigations during the past decades covering the fauna of the entire Palearctic region.

Given the small amount of differences between the species in this group it had been assumed that species have diverged rather recently. This would in turn mean that DNA Barcoding runs the risk of not working properly due to issues such as incomplete lineage sorting or mitochondrial introgression. Well, that does not seem to be the case in this study:

The original analysis of data revealed several species having considerable (>1%) intraspecific variation and likewise clusters of unidentified specimens showing a distinct gap (>1%) from any pre-identified specimens. Altogether, twenty-five such cases were detected. All these were subjected to an in-depth morphological examination. This resulted in the detection of sixteen putative new species whose species integrity was independently supported by genetic and morphological uniqueness.

Even after some years in the business it is always surprising to see how well the method actually works. Even if we have initial reservations.

In summary, our results support many earlier observations that DNA barcodes effectively differentiate closely related species. We demonstrate that a comprehensive sampling of collection material is an efficient way to discover hidden portions of biodiversity and that by accelerating taxonomic workflow DNA barcoding provides an important tool that, when widely used, might substantially help to overcome the taxonomic impediment. Lepidoptera represents one of the most thoroughly investigated groups of insects, and our focal group has been under considerable previous taxonomic investigation. Our results therefore suggest that the assessment of insect species number may often be underestimated by the overlooking of morphologically similar species. Along with growing DNA barcoding activity, we assume an increasing rate of discoveries of new species across all insect groups and areas.

No comments:

Post a Comment