In 1818, when Shelley's tale was published, South America was relatively sparsely populated.
In her 1818 novel Frankenstein, Mary Shelley has the monster ask Dr. Frankenstein for a mate, and the creature promises that he and his female counterpart would then go live in some remote corner of South America and never bother humans. The doctor initially agrees, then changes his mind.
That was a good call.
One basic principle in biology is that of competitive exclusion. This is something that we see on a daily baisis, but have only belatedly come to recognize. Take, for example, the European starling: 18 pairs were released in New York during the 1800s because some idiot thought they were pretty. Fast forward to today, and they're everywhere, driving out woodpeckers and other cavity nesters through sheer aggression.
Had the doctor acceded, built a bride for Frankenstein, and allowed the pair to relocate to an area in which they could thrive, we might well be facing the same issues that presently bedevil our feathered cavity-nesting friends.
Shelley "accurately anticipated fundamental concepts in ecology and evolution by many decades," writes Yeakel in a post at Phy.org.