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Oedipina capitalina was discovered a few years ago. This specimen was found in Honduras. It is listed as "insufficient data" but may in fact be in great danger of extinction.

Half of the species we know little about may be threatened with extinction

We know very little about very many species. Unfortunately, that’s often not a good sign.

Often we simply do not know enough about a species to know how it is doing. On the recognised red list from the International Union for Conservation of Nature (IUCN), thousands of plants and animals are listed as “data deficient”.

The researchers simply know too little about these species to be able to form an opinion on whether the species are threatened with extinction or not. But now we understand a little bit more, and unfortunately the news isn’t good this time either.

“We looked at species that are relatively poorly known, but where at least the geographical distribution is known. These species tend to be threatened with extinction more often than those we know more about,” says Francesca Verones, a professor at NTNU’s Industrial Ecology Programme.

In fact, over half of these lesser-known species could be in danger of disappearing.

Additionally, there are other species that are even less known. We can't even make claims about whether these are in trouble or not.

Fortunately, some of the species we know little about are probably faring just fine. The horn shark Heterodontus francisci is likely widespread in parts of the area where it is found on the west coast of North America. We just don’t know for sure yet.

1,000,000 or 147,000?

At least one million of our planet’s species are threatened with extinction, according to IPBES, the international panel of leading biodiversity researchers.

But you might have heard other numbers too.

The IUCN has assessed 147,000 species. Of these, 41,000 - or 28 per cent - are threatened.

Why this gap?

This gap partly exists because we haven’t discovered many of the species yet. Scientists assume that our planet has 10 million species, but we know of less than 20 per cent of them.

Some species probably disappear without us ever knowing they existed.

If we’re to take care of life on the planet, we first need to know what exists, so it is important to find out as much as possible about the organisms we share the planet with.

However, we often know very little, even about the species that we’re already aware of. Threats and trends are constantly changing, and there aren't enough researchers and helpers to survey everything. But technology can help.

Computer tools calculate probability

“We used machine learning to calculate the risk of extinction for 7,699 of the little-known species,” says Jan Borgelt, a postdoctoral fellow at NTNU’s Department of Energy and Process Engineering.

IUCN lists 20,469 species as "data deficient".

Various statistical tools can fill in some of these knowledge gaps with probabilities that computers arrive at.

These computer model-created probabilities were compared with individual examples that the researchers had gone through manually. The computer models proved to be extremely accurate.

Borgelt stresses that the intention with the models isn’t to replace the researchers’ work. But “they can provide a first estimate of the risk of species becoming extinct in cases where we don’t yet have enough data,” he says.

The researchers can save themselves work by using these computer models, which come in handy when the resources don’t match the workload.

For some species it will be too late. The toad Incilius periglenes was only found in a small area in Costa Rica. It was never numerous. Now no one has seen it since 1989.

Useful for protecting species

“We found that as many as 85 per cent of the amphibians that we have limited knowledge of are in danger of becoming extinct. For other groups, like mammals and reptiles, this applies to around half of the species,” says Borgelt.

Species unknown to us often face an uphill battle. But the consolation is that the new knowledge can be of great use if used correctly.

“More areas could become worthy of protective measures if we take species that we have little data on into account,” Borgelt says.

For example, so-called biodiversity ‘hotspots’ – areas particularly in need of being protected – could thereby become both more numerous and considered even more important.

“We find that the probability of extinction across species groups and regions varies a lot. This could indicate that some research that’s based on the risk assessments is not always correct,” says Verones.


Borgelt et al. More than half of data deficient species predicted to be threatened by extinction. Commun Biol., 2022. DOI: 10.1038/s42003-022-03638-9

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