DNA bar coding facilitates the identification of species

Developments in genetic engineering also facilitate taxonomy, ie the scientific classification of species. The species can be identified by a small piece of DNA, just as a product is identified in a store by a barcode. The method refines our understanding of species, species numbers, and biodiversity.

There are an estimated 10 million species in the world, of which we know about two million. Thus, biologists have enough work to describe and identify species, even though taxonomic work began 260 years ago. The assay guides, species collections, loupe, and microscope required for species identification will be accompanied by DNA sequencing. Each species has its own DNA barcode in the genome.

The identification of species using DNA traits has been developed for some twenty years. Now an effective method exists for animals, plants and fungi alike. The International Barcode of Life (IBOL) project is creating a DNA barcode library that will eventually aim to include all species in the world.

The Finnish sub-project FinBOL (Finnish Barcode of Life) has so far produced DNA barcodes for about 20,000 species.

“The University of Oulu coordinates DNA bar coding for Finland,” says Docent, Senior Curator Marko Mutanen from the University of Oulu’s Ecology and Genetics Research Unit. Mutanen is the coordinator of the FinBOL project. The project is part of the national FinBIF research infrastructure project.

“In addition to Oulu, the universities of Helsinki and Turku and a number of enthusiasts are involved.”

Faster, more reliable and more comprehensive

The idea of DNA bar coding was first introduced in 2003. At that time, it was found that the cytochrome c-oxidase gene (COI or cox1) of mitochondrial DNA was suitable for distinguishing between animal species.

Since then, barcode areas for fungi and plants have also been sought. In fungi, the ITS region of the nuclear genome is used as the DNA barcode region, and in plants, a combination of two genes (matK and rbcL) located in the green particle.

“Sequencing techniques have developed tremendously in recent decades,” says Marko Mutanen. “Price is no longer a significant barrier either.”

What are the benefits of DNA bar coding in biological research?

“There are many groups of species where it is almost impossible to distinguish between species solely on the basis of external characteristics. In these species, the DNA barcode is often the most practical way to identify the species. The DNA barcode also works in incomplete, broken samples and at all stages of an individual’s development, ”Mutanen lists.

“The method is fast and objective. Experts’ time is saved in the laborious identification phase. ”

The catch of a single insect trap can be thousands of individuals. Human identification of each individual requires a huge amount of work – now all genetic material can be isolated from prey and individuals can be identified for their species using DNA barcodes.

“Species monitoring can be done with new volume and accuracy. This is a huge advantage when monitoring changes by species or at Community level. ”

Cryptographic species emerge

Of particular interest to scientists are the so-called cryptic species.

“A cryptic species means a species that has previously been mixed with another species because of its similar appearance. The butterfly species we consider to be a noble (Pyralis regalis) is not that species based on DNA, but another, closely related species that is very difficult to distinguish from the noble species that occurs in Central Europe based on its appearance, ”says Mutanen.

DNA barcode research improves our understanding of biodiversity and increases our understanding of species relationships and the functioning of the entire ecosystem.

“Shuttle worms are ecologically very important breakers. It is impossible to distinguish them by their appearance, but with the help of a DNA barcode, that too is possible. ”

“The osprey is also an interesting group that does not know whether there are 500 or perhaps 5,000 species in Finland,” says Mutanen. “It’s currently being worked out for our master’s thesis.”

DNA – Vital sawdust

In recent years, Marko Mutanen has utilized DNA bar coding, especially in the study of sawdust.

“Sawmills include many species and are common and abundant, especially in northern latitudes. We have about 800 sawtooth species, but in many cases the species boundaries are unclear and it is difficult to identify their species by traditional methods, ”says Mutanen.

Sawdust is an important food for many birds. For example, the main food for the first summer of teer chicks is sawdust.
“There would be no tea without sawdust,” Mutanen says.

The endangered white-backed woodpecker is also addicted to sawdust, as it survives the winter by clicking on their larvae. Tens of thousands of junk-spotted larvae belonging to the sawdust mite live in one winter-backed woodpecker tree. The white-backed woodpecker lives over the winter with a few winter trees, decaying deciduous trees.

Saw saplings also include the infamous forest pest, the brown pine weevil. Better knowledge of an ecologically important species group is possible through DNA bar coding.

“For a few years, I collected sawdust for museum samples. I did one extra step: I removed the leg from each individual, from which the DNA barcode was sequenced. More than 7,000 tissue samples have now been analyzed. Species identification will be facilitated by a comprehensive reference library of DNA barcodes. ”


Dna – Abstract

Conventional methods for forensic species identification are mainly based on immunological procedures, which have limited applications for old and degraded specimens. The mitochondrial cytochrome b gene sequence has emerged in forensics among molecular methods. Recent investigations in the taxonomic field have suggested that a DNA-based identification system may aid the resolution of animal diversity and classification using sequence analysis and phylogenetic links. Selected gene sequences can be viewed as a genetic “barcode,” which is enclosed in every cell, and barcoding is a standardized approach for characterizing species using short DNA sequences as a diagnostic biomarker for organisms. The aim of this study was to evaluate the potential of barcode mitochondrial genes, such as the cytochrome c oxidase sub 1 (COI) and the 16S rRNA gene, as a forensic tool. We developed a new approach for species testing and identification with a singleplex PCR amplification that will be useful not only in criminal casework but also in biosecurity, food authentication, investigation against poaching or illegal trade of endangered species, and wildlife enforcement. Seven fragments ranging from 157 to 541 bp (base pairs) in humans were selected from COI and 16S rRNA genes by different redesigned sets of primers suitable for forensic purposes. The specificity of each primer pair was evaluated with a single PCR reaction on different substrates, and the diversity values were calculated by statistical tests to select a set of markers that could be useful in different caseworks. A case example of forensic species identification is also presented.

Article source: Oulu.fi and https://pubmed.ncbi.nlm.nih.gov/19405876/

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