Barcoding in spiders

DNA barcoding is a relatively recent idea proposing to use a fragment of the mitochondrial gene Cytochrome c Oxidase Subunit I (CO1) as a unique species diagnosis/identification tool in the animal kingdom. The broad appeal of DNA barcoding warranted immediate recognition as a promising molecular tool in taxonomy and beyond. Most authors agree that its utility is immense and the methodology seems to be getting huge positive boost by hundreds of studies published per year.

In spiders, DNA barcoding is an especially welcome tool with a variety of application possibilities:

 

• identification of juveniles which in spiders are generally not identifiable
• identification of females in genera where they are not easy distinguishable (e.g., Trochosa)
• matching both sexes in case they are collected at different time and locality
• detection of cryptic species diversity and ongoing radiation

The latter case may complement traditional taxonomy and is specifically suitable were traditional characters are not sufficiently well expressed. Usually this touches the question if the speciation process is already so progressed that a species rank is justified for the considered taxa. Good candidates for an application of barcoding data are

 

• sibling species and groups of closely related species (e.g., the Pardosa lugubris species group or the genus Eresus),
• species with disjunct distribution areas in Europe such as arcto-alpine species (e.g., Acantholycosa norvegica),
• species of Holarctic distribution where the potential problem of sibling species or species radiation has only rarely been considered in spiders.

Moreover, DNA barcoding has a huge potential for biodiversity estimation and monitoring, also in a frame of biological conservation, management of invasive alien species or species of medical importance.

To be able to make usage of the potential DNA barcoding for spiders, it is necessary to barcode as many species as possible, from many populations well-distributed over the total habitat of the species, with several specimens per population. In addition to such a basic data pool, a higher DNA-barcoding density may be meaningful in species which are investigated more intensively.

Figure 1: Percentage of European spider species included in araneae with barcode. Generated on 2021-10-31. Data source: www.boldsystems.org