[Scientists are increasingly seeing evidence of “dark
extinction” in museum and botanical garden collections.]
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SUNDAY SCIENCE: DISCOVERED IN COLLECTIONS, MANY NEW SPECIES ARE
ALREADY GONE  
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Katarina Zimmer
May 29, 2023
Undark
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_ Scientists are increasingly seeing evidence of “dark
extinction” in museum and botanical garden collections. _

The bee species Hypotrigona kleineri, discovered in resin samples
from eastern Africa first collected more than a century ago, is now
believed to be extinct, Seckenberg Natural History Museum

 

It could have been a scene from Jurassic Park: ten golden lumps of
hardened resin, each encasing insects. But these weren’t from the
age of the dinosaurs; these younger resins were formed in eastern
Africa within the last few hundreds or thousands of years. Still, they
offered a glimpse into a lost past: the dry evergreen forests of
coastal Tanzania.

An international team of scientists recently took a close look at the
lumps, which had been first collected more than a century ago by resin
traders and then housed at the Senckenberg Research Institute and
Natural History Museum in Frankfurt, Germany. Many of the insects
encased within them were stingless bees, tropical pollinators that can
get stuck in the sticky substance while gathering it to construct
nests. Three of the species still live in Africa, but two had such a
unique combination of features that last year, the scientists reported
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to be new to science: _Axestotrigona kitingae_ and _Hypotrigona
kleineri._

Species discoveries can be joyous occasions, but not in this case.
Eastern African forests have nearly disappeared
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century, and neither bee species has been spotted in surveys conducted
in the area since the 1990s, noted coauthor and entomologist Michael
Engel, who recently moved from a position at the University of Kansas
to the American Museum of Natural History. Given that these social
bees are usually abundant, it’s unlikely that the people looking for
insects had simply missed them. Sometime in the last 50 to 60 years,
Engel suspects, the bees vanished along with their habitat.
“It seems trivial on a planet with millions of species to sit back
and go, ‘Okay, well, you documented two stingless bees that were
lost,’” Engel said. “But it’s really far more troubling than
that,” he added, because scientists increasingly recognize that
extinction is “a very common phenomenon.”

The stingless bees are part of an overlooked but growing trend of
species that are already deemed extinct by the time they’re
discovered. Scientists have identified new species of bats
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beetles
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marsh plants
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and wildflowers
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studying old museum specimens, only to find that they are at risk of
vanishing or may not exist in the wild anymore. Such discoveries
illustrate how little is still known about Earth’s biodiversity and
the mounting scale of extinctions. They also hint at the silent
extinctions among species that haven’t yet been described — what
scientists call dark extinctions
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It’s critical to identify undescribed species and the threats they
face, said Martin Cheek, a botanist at the Royal Botanic Gardens, Kew,
in the United Kingdom, because if experts and policymakers don’t
know an endangered species exists, they can’t take action to
preserve it. With no way to count how many undescribed species are
going extinct, researchers also risk underestimating the scale of
human-caused extinctions — including the loss of ecologically vital
species like pollinators. And if species go extinct unnoticed,
scientists also miss the chance to capture the complete richness of
life on Earth for future generations. “I think we want to have a
full assessment of humans’ impact on nature,” said theoretical
ecologist Ryan Chisholm of the National University of Singapore.
“And to do that, we need to take account of these dark extinctions
as well as the extinctions that we know about.”

Many scientists agree that humans have pushed extinctions higher than
the natural rate of species turnover, but nobody knows the actual
toll. In the tens of millions of years before humans came along,
scientists estimate
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that for every 10,000 species, between 0.1 and 2 went extinct each
century. (Even these rates are uncertain because many species didn’t
leave behind fossils.) Some studies suggest that extinction rates
picked up at least in the past 10,000 years as humans expanded across
the globe, hunting large mammals along the way.

Islands
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were particularly hard hit, for instance in the Pacific, where
Polynesian settlers
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pigs and rats that wiped out native species. Then, starting in the
16th century, contact with European explorers caused
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extinctions in many places by intensifying habitat loss
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and the introduction of invasive species — issues that often
continued in places that became colonies. But again, scientists have a
poor record of biodiversity during this time; some species'
extinctions were only recognized much later
[[link removed](14)01618-2.pdf],
most famously the dodo, which had disappeared by 1700 after 200 years
of Europeans hunting and then settling on the island in the Indian
Ocean island it inhabited.

Key drivers of extinction, such as industrialization, have ramped up
ever since. For the past century, some scientists have estimated
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extinctions per 10,000 species— levels so high that they believe
they portend a mass extinction, a term reserved for geological events
of the scale of the ordeal that annihalated the dinosaurs 66 million
years ago. Yet some scientists, including the authors of those
estimates, caution that even these numbers are conservative. The
figures are based on the Red List compiled by the International Union
for Conservation of Nature, or IUCN, a bookkeeper of species and their
conservation statuses. As several experts
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noted
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the organization is slow to declare species extinct, wary that if the
classification is wrong, they may cause threatened species to lose
protections.

The Red List doesn’t include undescribed species, which some
estimate could account for roughly 86 percent
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8.7 million
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species on Earth. That’s partly due to the sheer numbers of the
largest species groups like invertebrates, plants, and fungi,
especially in the little-explored regions around the tropics. It’s
also because there are increasingly fewer
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experts to describe them due to a widespread lack of funding and
training, noted conservation ecologist Natalia Ocampo-Peñuela of the
University of California, Santa Cruz. Ocampo-Peñuela told Undark that
she has no doubt that many species are going extinct without anyone
noticing. “I think it is a phenomenon that will continue to happen
and that it maybe has happened a lot more than we realize,” she
said.

Studies of animal and plant specimens in museum and herbaria
collections can uncover some of these dark extinctions. This can
happen when scientists take a closer look
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analysis
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on specimens believed to represent known species and realize that
these have actually been mislabeled, and instead represent new species
that haven’t been seen in the wild in decades. Such a case unfolded
recently for the ichthyologist Wilson Costa of the Federal University
of Rio de Janeiro, who has long studied the diversity of killifish
inhabiting southeastern Brazil’s Atlantic Forest. These fish live in
shady, tea-colored acidic pools that form during the rainy season and
lay eggs that survive through the dry period. These fragile conditions
make these species extremely vulnerable to changes in water supply or
deforestation, Costa wrote to Undark via email.

In 2019, Costa discovered [[link removed]]
that certain fish specimens collected in the 1980s weren’t members
of _Leptopanchax splendens_, as previously believed, but actually
represented a new species, which he called _Leptopanchax sanguineus_.
With a few differences, both fish sport alternating red and metallic
blue stripes on their flanks. While _Leptopanchax splendens_ is
critically endangered, _Leptopanchax sanguineus_ hasn’t been spotted
at all since its last collection in 1987. Pools no longer form where
it was first found, probably because a nearby breeding facility for
ornamental fish has diverted the water supply, said Costa, who has
already witnessed the extinctions of several killifish species. “In
the case discussed here, it was particularly sad because it is a
species with unique characteristics and unusual beauty,” he added,
“the product of millions of years of evolution stupidly
interrupted.”
Similar discoveries have come from undescribed specimens, which exist
in troves for diverse and poorly-studied groups of species, such as
the land snails that have evolved across Pacific Islands. The mollusk
specialist Alan Solem estimated in 1990 that, of roughly 200 Hawaiian
species of one snail family, the _Endodontidae,_ in Honolulu’s
Bishop Museum, fewer than 40 had been described. All but a few are now
likely extinct, said University of Hawaii biologist Robert Cowie,
perhaps because invasive ants feasted off the snails’ eggs, which
this snail family carries in a cavity underneath their shells.
Meanwhile, Cheek said he’s publishing more
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and more
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new plant species from undescribed herbaria specimens that are likely
already extinct in the wild.

Sometimes, though, it’s hard to identify species based on individual
specimens, noted botanist Naomi Fraga
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programs at the California Botanic Garden. And describing new species
is not often a research priority. Studies that report new species
aren’t often cited by other scientists, and they typically also
don’t help towards pulling in new funding, both of which are key to
academic success, Cheek said. One 2012 study concluded
[[link removed](12)01248-1.pdf]
it takes an average of 21 years for a collected species to be formally
described in the scientific literature. The authors added that if
these difficulties — and the general dearth of taxonomists —
persist, experts will continue to find extinct species in museum
collections, “just as astronomers observe stars that vanished
thousands of years ago.”

Museum records may only represent a fraction of undescribed species,
causing some scientists to worry that many species could disappear
unnoticed. For some groups, like snails, this is less likely, as
extinct species may leave behind a shell that serves as a record of
their existence even if collectors weren’t around to collect live
specimens, noted Cowie. For instance, this allowed scientists to
identify [[link removed]]
nine new and already-extinct species of helicinid land snails by
combing the Gambier Islands in the Pacific for empty shells and
combining these with specimens that already existed in museums.
However, Cowie worries about the many invertebrates such as insects
and spiders that won’t leave behind long-lasting physical remains.
“What I worry about is that all this squishy biodiversity will just
vanish without leaving a trace, and we’ll never know existed,”
Cowie said.

Even some species that are found while they are still alive are
already on the brink. In fact, research suggests that it’s precisely
the newly described species that tend to have the highest risk of
going extinct. Many new species are only now being discovered
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they’re rare, isolated, or both — factors that also make them
easier to wipe out, said Fraga. In 2018 in Guinea, for instance,
botanist Denise Molmou of the National Herbarium of Guinea in Conakry
discovered a new plant species which, like many of its relatives,
appeared to inhabit a single waterfall, enveloping rocks amid the
bubbly, air-rich water. Molmou was the last known person to see it
alive.

Just before her team published their findings in the Kew Bulletin
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year, Cheek looked at the waterfall’s location on Google Earth. A
reservoir, created by a hydroelectric dam downriver, had flooded the
waterfall, surely drowning any plants there, Cheek said. “Had we not
got in there, and Denise had not gotten that specimen, we would not
know that that species existed,” he added. “I felt sick, I felt,
you know, it’s hopeless, like what’s the point?” Even if the
team had known at the point of discovery that the dam was going to
wipe it out, Cheek said, “it’d be quite difficult to do anything
about it.”

While extinction is likely for many of these cases, it’s often hard
to prove. The IUCN requires targeted searches to declare an extinction
— something that Costa is still planning on doing for the killifish,
four years after its discovery. But these surveys cost money, and
aren’t always possible.

Meanwhile, some scientists have turned to computational techniques to
estimate the scale of dark extinction, by extrapolating rates of
species discovery and extinctions among known species. When
Chisholm’s group applied
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method to the estimated 195 species of birds in Singapore, they
estimated that 9.6 undescribed species have vanished from the area in
the past 200 years, in addition to the disappearance of 58 known
species. For butterflies in Singapore, accounting for dark extinction
roughly doubled
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the extinction toll of 132 known species.

Using similar approaches, a different research team estimated
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the proportion of dark extinctions could account for up to just over a
half of all extinctions, depending on the region and species group. Of
course, “the main challenge in estimating dark extinction is that it
is exactly that: an estimate. We can never be sure,” noted Quentin
Cronk, a botanist of the University of British Columbia who has
produced similar estimates
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Considering the current trends, some scientists doubt
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even possible to name all species before they go extinct. To Cowie,
who expressed little optimism extinctions will abate, the priority
should be collecting species, especially invertebrates, from the wild
so there will at least be museum specimens to mark their existence.
“It’s sort of doing a disservice to our descendants if we let
everything just vanish such that 200 years from now, nobody would know
the biodiversity — the true biodiversity — that had evolved in the
Amazon, for instance,” he said. “I want to know what lives and
lived on this Earth,” he continued. “And it’s not just dinosaurs
and mammoths and what have you; it’s all these little things that
make the world go round.”
Other scientists, like Fraga, find hope in the fact that the
presumption of extinction is just that — a presumption. As long as
there’s still habitat, there’s a slim chance that species deemed
extinct can be rediscovered
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populations. In 2021, Japanese scientists stumbled across the fairy
lantern _Thismia kobensis_, a fleshy orange flower only known from a
single specimen collected in 1992. Now efforts are underway to protect
its location and cultivate specimens for conservation.

Fraga is tracking down reported sightings
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species she identified in herbaria specimens: _Erythranthe marmorata,_
which has bright yellow petals with red spots. Ultimately, she said,
species are not just names. They are participants of ecological
networks, upon which many other species, including humans, depend.

“We don’t want museum specimens,” she said. “We want to have
thriving ecosystems and habitats. And in order to do that, we need to
make sure that these species are thriving in, you know, populations in
their ecological context, not just living in a museum.”

_KATARINA ZIMMER is a science journalist. Her work has been published
in The Scientist, National Geographic, Grist, Outside Magazine, and
more._

_This article was originally published on Undark [[link removed]].
Read the original article
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_UNDARK is a non-profit, editorially independent digital magazine
exploring the intersection of science and society. It is published
with generous funding from the John S. and James L. Knight Foundation,
through its Knight Science Journalism Fellowship Program at MIT._

_Undark was co-founded in 2016, under the auspices of the Knight
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_The name Undark arises from a murky, century-old mingling of science
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__

‘Man, The Hunter’? Archaeologists’ Assumptions About Gender
Roles In Past Humans Ignore An Icky But Potentially Crucial Part Of
Original ‘Paleo Diet’
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It’s an open question whether ethnographic accounts of labor are
truly representative of recent hunter-gatherers’ subsistence
behaviors. Regardless, they definitely fueled assumptions that a
gendered division of labor arose early in our species’ evolution.

By Raven Garvey
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May 30, 2023
The Conversation

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