Invasive species
I stands for 'invasive species'
Invasive or introduced pest species have caused many native animals and plants to become extinct across the world.
People use a lot of different crops and domesticated animals for farming, and a lot more animals and plants (like mice, rats, cockroaches and weeds) live and thrive around us even if we don't want them to!
As people have spread around the world, they have taken many of these species with them, either deliberately or accidentally.
Introduced species often have a very harmful effect on native species.
For example, 24 rabbits were introduced to Australia in 1859 for hunting. Rabbits breed quickly, and, in an environment without any of their natural predators, their numbers increased so quickly that in less than a hundred years there were 600 million across the whole continent! The rabbits took over the resources and habitats of native species, like the bandicoot, which is now endangered.
Some people still transport animals from one country to another, smuggling exotic species for an illegal trade.
This isn't good, as history tells us that animals can only be introduced to a new habitat after extensive scientific study has shown that these introductions can only benefit the environment and not damage native species.
