The biodiversity on our planet is huge, but how many and which species there are is only known to a fraction. One of the reasons for this is that often only a few specialists can recognize the subtle characteristics and differences of the species. But that could change now: Scientists have now simplified the determination with the help of genetic “barcoding” and made it cheaper so that it will soon be able to be used by any layperson.
Whether amphibians, insects or exotic plants: worldwide the loss of species is progressing ever faster – according to estimates, around one million species are acutely threatened with extinction. The combined effects of climate change, habitat loss and direct extermination are causing biodiversity to shrink dramatically in many places. But all of this could only be the tip of the iceberg, because a large part of the organisms on our planet are not yet known to us. According to estimates by experts, there could still be up to 20 million undiscovered species.
Gene snippets instead of external features
The problem with this is that the identification of animal and plant species is time-consuming and often only a few specialists worldwide have the knowledge necessary to distinguish between certain species on the basis of subtle external characteristics. In addition, some species are so similar externally that a clear distinction as a species is hardly possible based on these characteristics alone. This is one of the reasons why biologists are increasingly turning to a method that shows them the “inner values” of a living being – the genes. Based on the differences in the DNA code, not only can species be separated from one another, but still unrecognized species can be identified in this way.
This is made possible with the help of so-called DNA barcoding. Excerpts of the genetic code of an animal or a plant are read out and compared with gene codes stored in central databases. In contrast to a complete genome sequencing, the entire genome is not evaluated, but only certain “tags” – small sections of the DNA code that reflect affiliations and relationships particularly well. In most cases, these sections do not come from the genetic material in the cell nucleus, but from the mitochondrial DNA, the genes that are located in the power plants of the cell, the mitochondria.
Barcoding easy and cheap
Until now, however, this barcoding was expensive and time-consuming – that is now about to change. Scientists working with Amrita Srivathsa from the National University of Singapore have succeeded in drastically simplifying the barcoding. This was made possible thanks to a new generation of sequencing machines, the so-called MinION. These fit in every pocket and can deliver results within a very short time. “Fortunately, we have succeeded in simplifying the work steps so much that the costs have been reduced to less than ten cents per copy,” explains Srivathsan. “This is what makes the broad use of this methodology for biodiversity discovery and the monitoring of species loss possible”.
In extensive tests, the research team also checked whether the miniaturized device is also suitable for the broad identification of species and whether it can read the genetic code with sufficient precision. The result was positive: “We document that the MinION barcodes are more than 99.9 percent identical to the established barcodes from Sanger and Illumina,” reports the team. In a field study in Singapore, university students have already examined more than 33,000 plants and animals in a mangrove area using MinION. As a result, more than 150 new species of insects and other mangrove dwellers have been discovered.
Species identification for everyone
According to the scientists, the simplified and inexpensive barcoding could usher in a whole new era of species identification. This is because even laypeople can quickly learn to identify and document animal species in the garden, field or forest using the MinION system. An additional, freely accessible bioinformatics tool called ONTbarcoder then makes the MinION results interpretable for everyone. “We are convinced that the method presented will help protect biodiversity and will help a large number of interest groups such as government organizations, universities, museums and private associations in biodiversity research,” says Rudolf Meier, head of the Center for Integrative Biodiversity Discovery at the Museum für Naturkunde Berlin.
Source: Museum für Naturkunde – Leibniz Institute for Evolution and Biodiversity Research; Technical article: BMC Biology, doi: 10.1186 / s12915-021-01141-x