DNA Barcoding Reveals Hidden Species

The Earth is filled with species diversity, much of which remains unknown. While scientists have identified between two and three million species, many more remain undiscovered, often referred to as "biological dark matter," a term borrowed from astrophysics.

“We want to demonstrate how we can gain a better overview of biological dark matter by using DNA barcoding,” explained Emily Hartop, Associate Professor at the Norwegian University of Science and Technology (NTNU).

Although DNA barcoding, or in this case "megabarcoding," may seem complex, it is an accessible and effective method for identifying species.

Why Some Species Remain Unknown

Hartop, who works at NTNU’s Department of Natural History, is part of a team accustomed to discovering new species. However, due to practical challenges, vast numbers of species remain unidentified.

“Biological dark matter often exists in groups consisting of very many species which we have not yet studied in any great depth,” Hartop noted.

Many of these species are located in remote or hard-to-reach areas, such as the ocean, or are found in small, elusive populations. Even in well-studied regions like Europe and North America, researchers are far from having a comprehensive understanding of biodiversity.

“These unknown species can be found everywhere,” Hartop added.

A Massive Task with Limited Experts

One major challenge is the lack of trained researchers. With an estimated nine million species on Earth (excluding bacteria and single-celled organisms), identifying and cataloging them is an enormous task.

Many species look so similar that even experienced researchers may struggle to differentiate them.

New Methods Simplify the Process

Fortunately, biologists are increasingly turning to DNA barcoding.

“In DNA barcoding, you only need a tiny bit of DNA to identify a species,” Hartop explained.

A DNA sequence is compared to a database of previously documented species. Expanding these reference libraries is an ongoing effort supported by national and international projects.

Large Numbers of Unknown Insects Identified

In this study, researchers focused on insects in Sweden, sampling flies from 37 habitats across four seasons. They analyzed 31,800 DNA samples with remarkable results.

“For example, we found a total of 549 different potential species of scuttle fly. This is a surprisingly high density and diversity,” Hartop shared.

Of these, 175 scuttle fly species were new to Sweden, with 374 already recognized.

Environmental Impact on Species Composition

The study also highlighted how environmental changes influence species distribution.

“With regard to scuttle flies, we see that the prevalence of different species is influenced by climate factors. For example, it appears that 29% of the species respond positively to an increase in average temperature, while 18% respond negatively,” Hartop explained.

The Importance of Cataloging Biodiversity

“It is important to gain an overview of the biodiversity around us. This means studying the inconspicuous but species-rich groups. We live in a time where biodiversity is under threat, including the unknown species,” Hartop emphasized.

The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) lists habitat loss as the biggest threat to biodiversity, followed by overexploitation, pollution, climate change, and invasive species.

DNA barcoding could play a critical role in identifying and preserving biodiversity before it’s lost.

“We see that this method can help us to quickly and efficiently gain an overview of the species. The time is ripe to explore the biological dark matter,” Hartop concluded.