Alien species driving global extinctions?

London: Alien species -- those not native to a specific location -- are the main driver of recent extinctions in both animals and plants worldwide, according to a study published Monday.

Researchers at University College London (UCL) in the UK found that since 1500 AD, alien species have been solely responsible for 126 extinctions, 13 per cent of the total number studied.

Of 953 global extinctions, 300 happened in some part because of alien species, and of those 300, 42 per cent had alien species alone listed as the cause of their demise.

The study, published in the journal Frontiers in Ecology and the Environment, used data from the 2017 International Union for Conservation of Nature (IUCN) Red List on the total numbers of species that are considered to have gone extinct globally since 1500 AD.

In total, 261 out of 782 animal species (33.4 per cent) and 39 out of 153 plant species (25.5 per cent) listed aliens as one of their extinction drivers.

In contrast, native species impacts were associated with only 2.7 per cent of animal extinctions and 4.6 per cent of plant extinctions.

"Some people have suggested that aliens are no more likely than native species to cause species to disappear in the current global extinction crisis, but our analysis shows that aliens are much more of a problem in this regard," said Tim Blackburn, a professor at UCL.

"Our study provides a new line of evidence showing that the biogeographical origin of a species matters for its impacts. The invasion of an alien species is often enough to cause native species to go extinct, whereas we found no evidence for native species being the sole driver of extinction of other natives in any case," Blackburn said.

The IUCN Red List identifies 12 broad categories of extinction drivers, including alien species, native species, biological resource use (hunting and harvesting) and agriculture.