The species that go extinct before we even know they exist

A team of researchers from China, Brunei and Australia have warned that newly discovered and unknown animal species may be at a higher risk of extinction than their more well-known, charismatic counterparts.

The study, led by Jiajia Liu of Fudan University, China, is the first of its kind to explore how a more recent discovery date impacts extinction rates. It suggests we may be vastly underestimating the already staggering rates of biodiversity loss happening around the globe.

“There’s been lots of recent discussions about extinction rates, but there’s a whole lot of undescribed biodiversity out there,” notes study co-author David Lindenmayer, a forest ecologist from the Australian National University (ANU).

“Once you start looking into the description and discovery of new species, it turns out that they are the ones most at risk of extinction.”

Using data compiled from the International Union for Conservation of Nature (IUCN) Red List, the researchers analysed more than 50,000 species across five vertebrate groups. Of all the vertebrate species described in the first nine years of the modern taxonomic nomenclature (1758-1767), 11.9% are now threatened. But of those species discovered in the nine years between 2011 and 2020, 30% were threatened.

Alarmingly, based on their projections, the number of newly discovered species listed as threatened could rise to nearly 50% by 2050.

“What we discovered was that the species that are poorly known, that we only just described, were the ones that had the highest extinction risk,” says Lindenmayer. “And what that really means is that there’s likely to be a very large number of species that are undescribed that are going to go extinct before we even describe them.”

There’s actually a name for when that happens: it’s called a centinelan extinction.

New species are being uncovered all the time, which might seem like a conservation win, but the new study suggests these species and all their cryptic, undiscovered counterparts are at serious risk. 

While there are around 1.5 million species formally described, there’s an estimated 8.7 million species actually living on the planet; it means there’s likely a yawning gap between the number of species we know are threatened and the number of species that are actually threatened.

“Newly described species are often rarer, and so we’ve overlooked them,” explains Lindenmayer. “And some of them are quite specialised, and we know that specialised animals can often be in trouble.”

There’s also the added complication of the illegal wildlife trade. “There’s an immediate black-market demand for these kinds of [newly discovered] beasties,” Lindenmayer notes, which can hasten their advance towards oblivion.

And Lindenmayer says the kinds of environments that play host to these undiscovered species tend to be biodiversity hotspots, like tropical rainforests, which are undergoing drastic changes the world over.

So, what can we do here in Australia to shore up our rich but embattled biodiversity?

“We’ve got to do much better, focused protection in biodiversity hotspots in Australia,” says Lindenmayer. And that includes stopping ourselves from making what he calls “really dumb decisions in the environment”.

“A good example is, why are we going to have 6,000 extra hectares of open-cut coal mine in North Queensland when it’s going to destroy habitat for animals like greater gliders and koalas,” he says. “That’s really dumb.” 

This year koalas, for the first time, made the unenviable shift from the vulnerable to the endangered species list across much of Australia’s eastern states.

Lindenmayer also says we need a dedicated research effort around conserving threatened species. He cites the now-defunct Threatened Species Recovery Hub, which closed at the end of 2021 and has not been replaced by a similar organisation.

“You need to bring top-quality scientists together with good managers and conservation practitioners,” he says. And it’s particularly important here in Australia, where we have such extraordinarily biodiverse ecosystems, chock-full of species found nowhere else on Earth.

The researchers also recommend targeted surveys in biodiversity hotspots to try and catalogue those hidden species and help them before they become invisible casualties.

And there’s no shortage of these globally important hotspots in Australia, though they all face myriad threats. There’s the Great Western Woodlands in south-western WA, known as the largest and healthiest temperate woodland left on Earth. Then there’s the rainforests of northern Australia, and the temperate wet sclerophyll forests of Victoria, New South Wales and Tasmania, which house some of the tallest trees on Earth.

“There’s a lot of species discoveries to be made in these places,” Lindenmayer says. “And there’s a lot of need for urgent protection in some of these areas as well.”

But all of those areas and their rare and threatened species face encroaching and interrelated threats, including feral animals, land-clearing, logging, urbanisation and climate change.

“Australia leads the world in skin cancer but it also leads the world in mammal extinctions,” Lindenmayer says. “So, we’ve got some significant issues to deal with.”

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