With the advent of the modern world--say after 1492 or so- and the many resultant migrations, exiles, conquests, immigrations, colonializations, enslavements, and easier travel, there are many animals and plants that are now found in places that they shouldn't be. Well maybe, "shouldn't" is the wrong word. But sometimes flora and fauna pop up in regions where they have no place in the food chain or no natural predators.
These organisms, intent on survival, make their own niche, which invariably causes problems for local flora and fauna. We've heard urban fairy tales of people flushing crocodiles down the toilet only to have said crocodiles survive to become deadly predators hungry for human flesh. I think I've seen a few low budget movies with that premise.
Anyway it's not a fantasy that in the Florida Everglades, people have accidentally, purposely, and almost always stupidly released animals into the environment that have destroyed much of the other flora and fauna, thus worsening the area for everyone. The latest example of this is the Burmese python.
A team searching under dense vegetation in the pine flatwoods of the Everglades late last year came upon a slithering sight, the likes of which no one had found before in those parts: 215 pounds of snake. It was the largest Burmese python ever found in Florida, breaking a record set by the invasive species in 2016 at 140 pounds, according to the Conservancy of Southwest Florida.