Plants and animals that do not have enough data to be properly assessed appear to be at twice the risk of extinction as those that have been evaluated, meaning more species could be wiped off the planet than previously thought, a study has warned .
Researchers looked at the extinction risk of species assessed on the Red List of Threatened Species and found that 56% of species in the Data Deficient (DD) category were threatened, compared to 28% of those assessed.
A species is considered DD if there is not enough data on its distribution or population, and these species are “generally ignored” in studies analyzing biodiversity impacts, researchers wrote in the paper, published in Communications Biology. The Red List, created by the International Union for Conservation of Nature (IUCN), is used by governments to determine which species should be prioritized for conservation measures.
The IUCN assesses more than 140,000 species based on criteria such as population size, trends and threats. There are 20,000 DD species on the Red List, and policy makers often consider them Least Concern, but this study showed that a much higher proportion of these species are threatened. Scientists said 85% of DD amphibians were at risk, as well as more than half of mammals, reptiles and insects.
Species may be DD because there are very few of them, sightings are rare or they may be cryptic species, making it difficult to estimate their population. To overcome these problems, the researchers created an algorithm that predicted the likelihood that species were at risk of extinction based on key factors they knew, such as the global distribution of those species, climatic conditions, changes in land use, pesticide use, and threats from invasive species . species. Researchers ran the algorithm on DD species if their geographic distribution was known, which is for about 38% of them.
Some DD species with very high probabilities of being at risk included the Sierra Miahuatlan spikethumb frog, which has a 95% chance of being threatened with extinction, as does the Sholai nightfrog, and a Mexican fish called Ajijic silverside.
Previous studies have looked at the risk of extinction of DD species, but this is the most far-reaching, looking at 21 taxonomic groups – still “a tiny fraction of what exists in the world”, according to lead researcher Jan Borgelt at the University of Norway. for Natural Sciences and Technology (NTNU).
Borgelt said: “Overall, it is more striking that across almost all land and coastal areas in the world, the average extinction risk would be higher if we took into account data-deficient species.” If DD species were included, 33% of red-listed species would be threatened, as opposed to 28%, the algorithm predicted.
Central Africa, southern Asia and Madagascar are the regions with the largest number of DD species at risk, although the researchers have not looked at why this might be the case. As many as half of DD marine species living in coastal areas are at risk of extinction.
Prof Jane Hill of the University of York, who is also a trustee of the British Ecological Society and was not involved in the research, said: “The study is important because the approach they use [machine learning methods] can be used on many more species.”
Around 18,000 invertebrates are assessed for extinction on the red list, but 27% are DD. The rate of extinction in insects is eight times faster than that of birds, mammals and reptiles, according to analysis published last year, with known declines likely to be the “tip of the iceberg”. Research has shown that vertebrates receive almost 500 times more funding for each species than invertebrates, which are perceived as less “charismatic”.
Hill said: “It has long been recognized that the IUCN Red List method is focused on only a small proportion of all species on Earth and that it needs to be more representative. So although this study provides more information about DD species, we still know very little about most species on earth.”
Some of the DD species are endangered
An example where the algorithm can be used is with the newly recognized Rice’s whale, which scientists thought might be a species for nearly a decade, although it took years to gain official recognition. Now there are only around 50 of them left, in the area affected by the Deepwater Horizon oil spill, where there is a lot of boat traffic and oil and gas extraction. There is no local outcry because no one knows it exists, says marine scientist Dr Chris Parsons of the University of Exeter, who believes the DD category should be given a ‘presumed threatened’ status. He said: “Had immediate action been taken years ago when they first suspected a new species, it could have forced research to be carried out immediately and initiated emergency measures that could have stopped it from becoming critically endangered.”
Of the 23 beaked whale species on the red list, seven are DD. They spend a lot of time underwater (their dives can last three hours) and are difficult to see in the wild, but they are at risk from a number of threats, including man-made noise pollution in the ocean that can cause mass strandings. The data on beaked whales is so poor that the algorithm could not assess how vulnerable they are.
Indo-Pacific humpback dolphins in Southeast Asia were considered DD for a long time, so there was no funding and little interest in studying them. They are now considered “near threatened” and have become Hong Kong’s official mascot, as well as being listed under the US Endangered Species Act, which helps international conservation efforts.