New map shows where the 80% of species we don’t know about may be hiding

In 2012, researchers described a teensy, aspirin-sized chameleon, Brookesia nana, from a thin slice of rainforest in northern Madagascar. The species, which experts believe is the smallest reptile in the world, grabbed plenty of headlines worldwide.

Mario Moura, a former postdoctoral associate in ecology and evolutionary biology at Yale University and current professor at the Federal University of Paraíba in Brazil, says it’s pretty common to find species that are new to science, especially in parts of the world such as Madagascar.

“I think most people believe that we know most species on Earth … but in the best-case scenario, we know 20% of Earth’s species,” Moura told Mongabay in an interview.

Moura and his colleague, Walter Jetz, a professor of ecology and evolutionary biology at Yale, recently published a study in Nature Ecology & Evolution that investigates the untapped potential of the world’s unknown species, focusing on terrestrial vertebrates, including amphibians, reptiles, mammals and birds. The duo created a map of the world that shows where most undescribed terrestrial vertebrates might be located.

While previous studies have looked at how many undescribed species there are, this study aims to identify these species’ locations and the taxonomic groups to which they belong.

“We know that 80% of Earth’s species are undiscovered, but where are they?” Moura said. We are moving from [questions] like, ‘How many species are there’ to questions like ‘where’ and ‘what.'”

The researchers compiled data from more than 32,000 terrestrial vertebrates using the Map of Life — a global database of known species and their distributions, a project led by Jetz — to figure out what species have yet to be described and where they are. They also looked at numerous factors that might determine the probability of unknown species in an area, including whether species in a particular area have traits that make them harder to identify. For instance, species with smaller body sizes, tinier ranges, and that live in inaccessible habitats are probably less likely to be found than species with larger body sizes and wide ranges.

 

“When you think about a species that live in similar places, they tend to share similar characteristics, similar features,” Moura said. “So if a region is known to have many species with traits that are hard to detect … that region will likely hold many undescribed species.”

The resulting maps show that tropical forests in countries like Brazil, Indonesia, Madagascar and Colombia hold the most considerable amount of unknown species, accounting for about a quarter of potential discoveries. The study also found that reptiles and amphibians probably account for the majority of undescribed species.

While many factors might contribute to species going undescribed, Moura says it’s mainly due to a lack of research funding and too few taxonomic experts in these regions who could accurately identify new species. But describing these unknown species is paramount for their protection, Moura said, adding that it can help inform discussions at the upcoming U.N. Biodiversity Conference (CBD COP15) in Kunming, China.

“We hope that they [the parties to the CBD] will … try to embrace these new findings about undiscovered biodiversity in the goals or at least [gain awareness] of the existence of this unknown species, because right now … undescribed species are not directly included in international goals,” Moura said.

“What really makes me happy about this research is the possibility that we can … stop ignoring undescribed species in conservation planning, and we can do something to avoid the extinction of those species in future generations,” he added.

According to another study, undescribed species account for about 15-59% of current extinctions, depending on the organism under consideration.

Boris Worm, a marine conservation biologist who co-authored a study that quantifies the number of undescribed species on land and the ocean, but was not involved in Moura’s study, called the new paper in Nature Ecology & Evolution a “terrific” piece.

“[The researchers] get into quite a bit more detail about what kind of species can be expected to be discovered and where, and I think that’s just really useful,” Worm told Mongabay in an interview.

He added that while places like the Brazilian Atlantic Forest, the Caribbean islands, Mesoamerica, Madagascar and Southeast Asia are already known to be biodiversity hotspots, the study provides new information about the taxonomic affiliations of the undescribed species in these parts.

Worm says some undescribed amphibians and reptiles may be going extinct without our knowledge.

“We can’t protect them … if we don’t know them,” Worm said. “We’re understanding more and more that every species on the planet has a role, and in one way or another, is linked to our well-being through the part they play in ecosystems.”

Citations: 

Mora, C., Tittensor, D. P., Adl, S., Simpson, A. G., & Worm, B. (2011). How many species are there on Earth and in the ocean? PLOS Biology, 9(8), e1001127. doi:10.1371/journal.pbio.1001127

Moura, M. R., & Jetz, W. (2021). Shortfalls and opportunities in terrestrial vertebrate species discovery. Nature Ecology & Evolution. doi:10.1038/s41559-021-01411-5

Tedesco, P. A., Bigorne, R., Bogan, A. E., Giam, X., Jézéquel, C., & Hugueny, B. (2014). Estimating how many undescribed species have gone extinct. Conservation Biology, 28(5), 1360-1370. doi:10.1111/cobi.12285

Banner image caption: The panther chameleon (Furcifer pardalis) was discovered in Madagascar in 2015. Image by Rhett A. Butler.

Elizabeth Claire Alberts is a staff writer for Mongabay. Follow her on Twitter @ECAlberts.

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