Lepidoptera are the second-most diverse order of insects (after Coleoptera – the beetles). There are about 180,000 known species of Lepidoptera and another 300,000 likely await description. This site is the on-line home of an effort that employs DNA barcoding to advance the identification and discovery of Lepidoptera. This work is being conducted by researchers with expertise in ecology, molecular evolution and taxonomy aided by many dedicated amateur lepidopterists. In these early days for the DNA barcode effort, we seek to broaden this alliance so that work can advance more rapidly and its scope can expand (see Get Involved).
Because there are so many species of Lepidoptera in so many places, it is not feasible to tackle the entire fauna as a single effort. Instead, we have begun barcoding Lepidoptera on three geographic scales- global, continental and regional. The global campaigns are taxonomically focused- they are assembling barcode records for two particularly charismatic families of moths – the Sphingidae and the Saturniidae. The continental and regional campaigns are more ambitious taxonomically – they are assembling barcode records for all species of Lepidoptera found in particular geographic realms. The first two continental campaigns are gathering barcode records for Australia and North America, while the first regional campaigns target the Lepidoptera of the Great Smoky Mountains National Park (USA) and Area de Conservación Guanacaste (Costa Rica).
All 6 campaigns share a common analytical approach. Work begins with the collection of specimens and the injection of information on each specimen into a project file on the Barcode of Life Database (BoLD). In addition to the date and location of its collection (and other collaterals, such as who identified it and where the specimen is stored), its image is placed in the database. A single leg is removed from each specimen, DNA is extracted and the barcode region (a short, standard segment of the mitochondrial COI gene) is PCR-amplified and sequenced. The sequence record migrates to BoLD where it is attached to the appropriate specimen record. Click here for a graphic of the analytical process.
The use of a checklist as a basis for the administration of specimen identifications is a critical aspect of each campaign. All barcoded specimens gain their identifications based on this list from the team of taxonomic specialists working on a campaign. In this way, progress toward complete barcode coverage can be easily monitored and each species is represented in the database by just one name. All barcoded specimens are deposited in a museum and are therefore available for double-checking and for long-term study. Voucher specimen identifications and the database are updated as new species are discovered and identifications revisited.
Each record combining information on a specimen with its barcode sequence represents a single entry in the barcode reference library. The barcode effort seeks multiple barcodes for each species, both at key sites and across its range. With an initial target of at least 10 specimens per species, there will be millions of barcode records when the ‘All Lepidoptera’ campaign is complete.
The three members of the genus Symmerista in eastern North American have long been distinguishable only by genitalic dissections, but barcodes now permit their separation.
In more than 95% of cases, species recognized through past taxonomic work have been found to possess distinct barcodes. A few very similar species share barcodes, reflecting cases where barcoding does not provide full taxonomic resolution. However, such cases are regularly offset in diversity tallies by the discovery of previously overlooked species that are revealed through investigations on those species found to include 2, 3 or more divergent barcode groups.
Two points are worth emphasizing. Firstly, DNA barcoding is not based on the presumption that all individuals of a species possess an identical barcode sequence. It is, instead, based on the premise that individuals of a species share very similar sequences and that the barcode arrays for different species are usually distinct. Secondly, DNA barcodes are never used as the sole basis for species recognition. Instead, DNA barcoding is used to flag cases of deep barcode divergence that may reflect overlooked species. When deep barcode divergences are revealed, new studies are launched to investigate if the different barcode lineages also show differences in morphology, ecology or other traits. In those cases where trait co-variation is revealed, the case for overlooked species builds.
As the barcode reference library emerges for a region, it can be used to identify newly collected members of those species represented in it. DNA barcodes are particularly valuable because they enable the identification of all life stages. As well, they provide a very effective tool for separating species that have highly variable phenotypes or that can otherwise only be distinguished through time-consuming genitalic dissections.