Hundreds of species of mammals living in the world’s tropical and Palearctic regions have yet to be discovered, a new study suggests.
A new predictive model developed by ecologists in the US estimates there are roughly 303 mammal species throughout the world that remain unknown to science.
Given the high extinction rates today, however, the experts warn many species could be wiped out before they’re ever found.
Hundreds of species of mammals living in the world’s tropics have yet to be discovered, a new study suggests. Most of these can likely be found in the tropics and Palearctic, with a high concentration in Africa, the researchers say. File photo
According to the team from the University of Georgia who developed the new model, the new research could help to guide conservation efforts for yet-undiscovered species.
‘With extinction rates increasing, it’s extremely important to be able to find new species before they disappear if we want to be able to understand the world that we’re living in,’ said lead author Molly Fisher, a doctoral student in the Odum School of Ecology.
In the new study, the researchers used statistical models to estimate the total number of mammal species in the world – both known and unknown.
The team harnessed a technique employed by a previous study published in 2011 to estimate the total number of plant species, relying on the relationship between the number of species descriptions published and the number and efficiency of taxonomists, with a dataset encompassing species described from 1760 through 2010.
The team investigated descriptions published in five-year increments during the time period.
‘We took their method and built onto it,’ said Fisher.
‘We decided to work with mammals because they are a group that everyone knows, and we’re getting to that point where we actually have discovered a majority of them.
Using species maps from the International Union for Conservation of Nature, they determined where these species might be hiding. The map above shows the areas most likely to hold undiscovered species, with blue representing regions with fewer, and red with most
‘With this method, we can see the pattern of how many species are described and how that’s related to how many taxonomists are working in a time period.
‘Maximum likelihood estimation figures out how many specie there are likely to have been to produce the pattern of description that we have seen,’ Fisher said.
With the new version of the technique, the taxonomic efficiency is able to increase exponentially over time, to reflect improvements in scientific technique.
The model estimated there are 5,860 mammal species in the world.
By subtracting the number of known species, they were able to derive an estimate for those yet to be discovered.
A new predictive model developed by ecologists in the US estimates there are roughly 303 mammal species throughout the world that remain unknown to science. Given the high extinction rates today, however, the experts warn many species could be wiped out. File photo
WHAT IS THE STATE OF THE EARTH’S SPECIES?
– Two species of vertebrate, animals with a backbone, have gone extinct every year, on average, for the past century.
– Currently around 41 per cent of amphibian species and more than a quarter of mammals are threatened with extinction.
– There are an estimated 8.7 million plant and animal species on our planet and about 86 percent of land species and 91 percent of sea species remain undiscovered.
– Of the ones we do know, 1,204 mammal, 1,469 bird, 1,215 reptile, 2,100 amphibian, and 2,386 fish species are considered threatened.
– Also threatened are 1,414 insect, 2,187 mollusc, 732 crustacean, 237 coral, 12,505 plant, 33 mushroom, and six brown algae species.
– The global populations of 3,706 monitored vertebrate species – fish, birds, mammals, amphibians, and reptiles – declined by nearly 60 per cent from 1970 to 2012.
– More than 25,000 species of 91,523 assessed for the 2017 ‘Red List’ update were classified as ‘threatened’.
– Of these, 5,583 were ‘critically’ endangered, 8,455 ‘endangered’, and 11,783 ‘vulnerable’.
Then, using species maps from the International Union for Conservation of Nature, they determined where these species might be hiding.
Since the greatest number of species overall are found in the tropics and the Palearctic region, these areas likely also have the most undiscovered species.
‘That was actually very interesting for me as well as for anyone else who’s looked at this,’ Fisher said.
‘We expected that the tropics would have the most species because the tropics are the least well studied and have a lot of cryptic species.
‘There may be more cryptic species in the tundra/taiga of the Palearctic than previously assumed or found.’