An essay published in the June 8 issue of Nature is causing something of a stir. Eighteen ecologists who signed the essay, titled “Don’t judge species on their origins,” “argue that conservationists should assess organisms based on their impact on the local environment, rather than simply whether they’re native,” as described in a recent Scientific American podcast.
In the essay, Mark Davis from Macalester College, St. Paul, Minnesota and colleagues argue that adherence to the idea of non-natives as “the enemy” is more a reflection of “prejudice rather than solid science,” wrote Brandon Keim in a Wired Science article. As the authors wrote, the “preoccupation with the native–alien dichotomy” among scientists, land managers and policy-makers is prohibitive to dynamic and pragmatic conservation and species management in a 21st century planet that is forever altered by climate change, land-use changes and other anthropogenic influences. As a result of this misguided preoccupation, claim the authors, time and resources are unnecessarily spent attempting to eradicate introduced species that actually turn out to be a boon to the environment; the authors cite the non-native tamarisk tree in the western U.S. as an example of this.
But some other ecological scientists believe that the authors of the essay are barking up the wrong tamarisk tree, so to speak. Not only is there a disagreement with the paper’s premise that there is an unjust bias against all non-natives, but other scientists assert that the harm non-natives are capable of causing should not be overlooked. Jessica Gurevitch, an ecologist at the State University of New York Stony Brook, stated that the authors “downplay some of the problems and uncertainties,” and she insists that the “just get used to [non-natives being the norm]” attitude is misguided. David Pimentel, an entomologist at Cornell University, has estimated invasive species damage in the U.S. at between $100 billion and $200 billion.
Nevertheless, the essay authors argue that “being indigenous doesn’t grant a species special rights to inhabit an ecosystem,” according to the Scientific American podcast, and Razib Khan from Discover’s blog Gene Expression reminds readers that “we [humans] are after all an invasive species oursel[ves]!” Furthermore, not all natives are economically and ecologically beneficial. For example, British Columbia has recently had one of the largest infestations of the mountain pine beetle, a species indigenous to pine forests of western North America, on record—an issue that has caused significant ecological impacts. And according to Mark Davis, many non-natives can actually boost biodiversity.
But is biodiversity always the ultimate goal? David Lodge, an ecologist at the University of Notre Dame, argues otherwise. While local biodiversity may at times increase with the introduction of non-native species, he asserts, “each locale may come to resemble the next,” embodying what some biologists call ‘the homogecene’. What’s more, discussions of the article have raised doubts about the essay’s supportive data regarding supposedly harmless species such as non-native honeysuckles.
Even so, “scientists who malign introduced plants and animals for thriving under favorable conditions seem to be disregarding basic ecological and evolutionary principles,” ecologist and historian of invasion biology Matthew Chew and ecologist Julie Stromberg both of Arizona State University asserted, according to a Physorg article. “Evaluating whether a species ‘belongs’ in a particular place is more complicated than just finding out how and when it arrived.” Authors of the Nature essay agree, saying that “classifying biota according to their adherence to cultural standards of belonging, citizenship, fair play and morality does not advance our understanding of ecology.”
What do you think about the Nature paper? What does give a species the “right” to thrive in a particular ecosystem, if not native status? Are non-natives unjustly persecuted, or is this controversy overplayed? Take part in the discussion by replying with a comment below.
Photo Credit: Steven Damron