In Europe, invasive water frogs, introduced by humans, are proliferating at the detriment of the native Yellow-Bellied Toad and Midwife Toad populations.

This is just one of many cases in which invasive species take over an ecosystem and displace the native species.

"The spread of invasive species is often supported, consciously or unconsciously, by the actions of humans and cannot easily be undone."

http://ow.ly/ZbypS
https://www.sciencedaily.com/releases/2 ... =hootsuite