That’s what researchers say in a new study. This would mainly concern small mammals, such as bats, rodents and moles.

There are currently around 6500 mammal species known to us. But with that we have probably only described 80 percent of the mammal species worldwide: hundreds of – mainly small – species would still be waiting to be discovered in 2022. And we have actually seen many of those species before, but are currently considered to be a species already known to us, while they actually deserve their own species name. Researchers write that in the magazine Proceedings of the National Academy of Sciences†

Genetic Research

“Small, subtle differences in appearance are much harder to spot when you look at a small animal that weighs 10 grams than when you look at an animal about the same size as a human,” said study researcher Bryan Carstens. “You can only determine (in the case of small animals, ed.) that they belong to different species if you perform a genetic analysis.”

And if we were to do that for all those small mammal species known to us, we would still come across quite a few new species, according to the researchers. “Based on our analysis, there are hundreds of undescribed mammal species worldwide,” said Carstens. “And that’s still a conservative estimate.”

Method

The researchers reached that conclusion after collecting and analyzing nearly 1 million gene sequences from 4,300 described mammalian species. “To analyze all this genetic data, we used a method called ‘automated species delimitation‘, which compares genetic sequences of related individuals with the goal of finding the differences and assigning individuals to the correct species based on those differences,” said study researcher Danielle Parsons. Scientias.nl from. “After we applied that method to our data, we found that up to a third of the species we worked with in our final analysis could be predicted to likely harbor undescribed diversity.”

In the rainforests

But where is the greatest chance of encountering ‘hidden species’? Parsons and colleagues have also looked into this. For example, their model predicts that undescribed species are particularly common within described species with a larger habitat. You have to think of a habitat that is so large that it is also very diverse; such a habitat promotes the development of new species that may look very similar to their relatives, but have genetically adapted themselves to a different corner of that habitat to such an extent that they can no longer be classified as part of the same species on the basis of their DNA become. In addition, the researchers expect that the tropical rainforests are still home to many undescribed species. That is also logical, because we already find most mammal species there – already now.

Species Conservation

So, based on the research, there are large habitats where we now assume that one species is thriving profusely, when in reality that habitat is broken up into smaller areas, each harboring different, but identical in appearance, species. And when you realize that, it immediately becomes clear why it is so important to find these hidden species. It could mean that a species that we now think is in good health actually has a much smaller population and is much more dependent on our protection than previously thought. “We can’t protect a species if we don’t know it exists,” Carstens said.

It may not be so spectacular to discover a species that in appearance is indistinguishable or hardly distinguishable from another species, already known to us, to which it was previously counted; it is certainly important, according to Parsons. “When people think of the discovery of new species, they often imagine expeditions to remote countries, where they then find species that are completely new to science. And such discoveries are undoubtedly very exciting and still take place – even in well-studied animal groups. A recent example of this is the discovery of the Sulawesi snouter, a mountain possum with a pig-like nose.” But the reality is that most of the new species being discovered today are not brand new, in the sense that we don’t know about their existence. Instead, it concerns individuals that we already know that they roam the earth, but we don’t realize yet that they deserve their own species name and wrongly count them as a different species. “For example, there are North American bats (Myotis lucifugus) in which several species can probably be found. And it is precisely these ‘hidden species’ that we wanted to detect with our analysis. Because the discovery of these hidden species is likely to lead to many other surprises.”

The research clearly argues for more (taxonomic) studies. But anyone who thinks it should be fairly easy – armed with enough time and money – to find all those hidden species is wrong, says Parsons. Even if we make an effort to discover all the species on Earth, there will always be undescribed species waiting to be discovered. That’s partly because identifying new species is a lot more complex than you might think. In addition, the formation of new species is also a continuous process. Species formation, in other words the process that leads to the formation of a new species, takes place on a spectrum. There is much discussion among taxonomists about the amount of change that a species must undergo in order to be classified as a new species (…) In many cases, speciation is custom work. In addition to genetic data, if you want to formally describe a species, you also have to look at other factors, such as geography, behavior and physiology. And to top it off, new species are constantly being formed. So new species continue to emerge over time. That may not seem very encouraging, but in fact it is very exciting, because with each new species we discover we come to understand the world around us better.”

There is therefore a lot of – and continuous – work to be done for taxonomists. And it is important to realize that this study only deals with mammals. “And mammals are arguably one of the most studied animal groups on the planet,” Parsons said. “Our results suggest that even among mammals many undescribed species are still to be found. And that in turn indicates that in other, much more diverse groups that have received much less attention, the number of undescribed species is probably many times higher. And that implies that we as a society urgently need to invest more in taxonomic research.”