Human activity is driving numerous species to extinction. Hunting, overfishing, reduction of habitats and many other negative things that we do are driving many species off of our planet. However, scientists from UCL say that there is another factor – invasive, also known as ‘alien’, species. As it turns out, these ‘alien’ species have been solely responsible for 126 extinctions since 1500.
Scientists considered 953 global extinctions. 300 (261 animal species and 61 plant species) of those had something to do with invasive species and 42 % of these 300 invasive species were the only suspect to be blamed for someone going extinct.
On the other hand, native species are not without guilt either – they are responsible for 2.7 % of animal extinctions and 4.6 % of plant extinctions. This shows that invasive species are much more damaging to ecosystems than previously believed. However, invasive species are not from outer space – they are just animals and plants that were relocated and became invasive in a different ecosystem. Scientists say that this proves how important the biogeographical origin of a species is in terms of their impact.
Researchers used data from the 2017 IUCN Red List to get a better view of global extinction and what could be driving them. The document lays down 12 broad categories of extinction drivers, including invasive species, native species, biological resource use and agriculture. According to this study, invasive species ranks the first in this list in terms of its significance and the biological resource use (such as hunting and harvesting) is the second, having affected 18.8% of those lost species. Alien species are the most significant driver for extinctions and among them mammalian predators are the worst offenders.
Although it might look like humans are good then, these alien species go to new ecosystems somehow. Sometimes they just catch a ride on a ship (like various rodents and even birds) and sometimes they are deliberately introduced. Is your cat local? It might be born in your town, but cats are originally from Africa. Introduced as pets they hunted local rodents that were unfamiliar with this new predator and drove species to extinction. Tim Blackburn, lead researcher from the study, said: “The invasion of an invasive 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”.
This just shows how sensitive ecosystems actually are. Humans should do their best to avoid introducing animals in new environments, especially predators. If invasive species did this damage before, it is most likely still happening – more and more animals are getting threatened by invasive species.