Maggie Koerth-Baker: What is an Invasive Species?


This isn’t just trivia. Invasive species control is always expensive, and you only get the resources to launch a full-court press against a plant or animal — like the hundreds of millions of dollars spent in the last six decades to get sea lamprey populations under control — on the rare and shining occasion when everyone in power agrees on what “harm” is. And so the definition of invasive species has also created fights within the biological sciences. In 2011, Mark Davis, a biology professor at Minnesota’s Macalester College, published an essay in Nature in which he and 18 co-authors argued that the field of invasion biology had become too weighted toward viewing all non-native species as bad and worthy of eradication. “Harm,” he argued, had come to mean “change.” “And, boy, this world is a bad place to be if any change is viewed as bad,” Davis told me.