Scientists Thought This Frog Was One Species for Nearly 200 Years. DNA Tells a Different Story.
A new genetic analysis of Bornean fanged frogs reveals that a species recognized since 1838 is actually six or seven distinct species — a finding with major implications for how scientists count and conserve the world’s wildlife.
For nearly two centuries, scientists classified a small brown frog living in the rainforests of Southeast Asia as a single species called Limnonectes kuhlii. Modern genetic tools are now revealing a far more complicated picture, one that could reshape understanding of biodiversity across the planet.
The discovery comes from research led by Chan Kin Onn, a herpetologist at Michigan State University. Chan and his colleagues analyzed DNA from frog specimens collected across the mountain rainforests of Malaysian Borneo, examining more than 13,000 genes across the frogs’ genomes — a level of detail impossible just a few decades ago.
The research was published Jan. 14 in the journal Systematic Biology.
Not One Species, but Not 18 Either
Genetic studies over the past two decades had suggested the frogs might represent as many as 18 different species rather than one. But the new research tells a more nuanced story. The frogs fall into multiple genetic clusters, though the researchers concluded only six or seven of those clusters qualify as distinct species.
“It’s not just one species. But it’s not 18 species, either,” Chan said.
The discovery challenges popular assumptions about how new species are found. Chan said it rarely involves dramatic treks into uncharted wilderness.
“Most people have this image of an intrepid explorer braving an isolated mountain or some other remote place, and stumbling across a creature that no one has ever seen before,” Chan said. “But most of the time it’s far less glamorous.”
Many new vertebrate species are identified by revisiting known populations and using improved data and technology to detect genetic differences that were previously invisible. Chan noted there are more than 9,000 amphibian species worldwide, with roughly 100 to 200 new species added each year. Many of those come from taking a closer look at animals scientists already knew about.
The Problem of Cryptic Species
The Bornean fanged frogs are what scientists call cryptic species — animals that appear nearly identical on the outside but are genetically distinct. To the human eye, these frogs look alike. But deep within their DNA, meaningful differences exist.
The researchers also detected significant interbreeding between the frogs, adding complexity. “We found a ton of gene flow going on,” Chan said.
Because genetic material moves between populations, the boundaries between potential species can become blurred. Chan said some proposed cryptic species may reflect differences in scientific methods rather than clear biological divisions. Where one researcher draws the line between species, another might not.
“It’s not like all of a sudden, boom. It’s more of a continuum,” Chan said.
Real Stakes for Conservation
The findings carry real weight for wildlife protection. A 2023 global study of roughly 8,000 amphibian species found that two out of five amphibian species are threatened with extinction, making them the most endangered group of vertebrates.
Chan emphasized the urgency of identifying species before they disappear. “There are so many species in the world that we still haven’t discovered, and that could go extinct before we can give them a name,” Chan said.
But he cautioned that splitting species too aggressively can complicate conservation decisions. With limited funding available to protect wildlife, how scientists categorize species directly affects which animals receive attention.
“We cannot possibly conserve everything, so we have to triage and decide how to allocate limited resources toward what we think are the highest priorities,” Chan said. “We could be putting names on things that shouldn’t be prioritized.”
A Much Bigger Picture
The implications extend far beyond frogs in Borneo. Similar genetic studies across animals — including insects, fish, birds and mammals — suggest many species could still be undiscovered.
Earlier estimates suggested Earth contained about 8.7 million species. Newer models that account for cryptic species indicate the total number could be anywhere from seven to 250 times higher. If accurate, the vast majority of life on Earth has yet to be formally identified.
Production of this article included the use of AI. It was reviewed and edited by a team of content specialists.
