Speaking of species and their origins

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

Author: Molly Taylor

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  1. It is a misguided essay. As noted as some of the authors are, to claim that the push to save native biodiversity is some kind of bias (akin to racism?), is a serious mis-interpretation of conservation biology. We are losing some species, and the reason is anthropogenic. Species we have assisted to proliferate at the expense of species we have assisted to go extinct are managed to minimize human influence on the environment. We had might as well embrace a human-dominated future and forget about rare species unable to cope with those new conditions, if we were to follow their line of logic. Yes, invasion is just another aspect of evolution. But using the Davis et al. argument, one could have also claimed that slavery was just another aspect of intraspecific competition, or some equally abhorrent social Darwinism. At some point, well-meaning people step in and do what’s right. Yes, that’s a value.

  2. I’m not sure what the point of this article is. Obviously any ‘judgement’ of any species is anthropomorphic, values-based, and not science. This is nothing new… all management or conservation of any sort is based on values.

    The most valid point I see here is that non native does not necessarily equal invasive. The vast majority of introduced species do not become invasive… and some native species DO, especially when people change the conditions in an ecosystem. I think it is a good idea to get away from using ‘non-native’ as a qualifier, and instead look at species based on how they act in an ecosystem.

    But… I fear most will read this article as an advocation of not managing invasive species. I see this as being harmful to conservation in the long run. While methods of management (ie: whether or not to use herbicide) are valid subjects of debate, there is a vast body of good science that indicates that invasive species lead to dramatic loss of biodiversity and ecosystem function. While ethically labeling loss of ecosystem function as ‘bad’ may be difficult for some to swallow, it is in our best interest to manage for diverse and stable ecosystems when we can, and to do damage control if we can’t. The phenomena of invasiveness in ecosystems is poorly understood, and hopefully future science will give us a better idea for how this works. In the meanwhile, we can only do what we can to reduce the harm we do while we try to we understand the implications of it.

    Also, there is a pretty solid element of hypocrisy here to condemn ‘ethical labeling’ of species and then call tamarisk a ‘boom’. It’s an odd statement to make anyway, since the plant seems to have more negative impacts to ecosystems and humans than positive ones (though it is a valid point that it may be proliferating mainly due to alterations of the natural hydrological regime via dams, etc). In any event, some species will certainly benefit from the spread of tamarisk. For that matter, coyotes and raccoons benefit from suburbanization, and many heat-tolerant species may benefit from climate change. I’m still quite OK with saying that climate change and urban sprawl are detrimental to ecosystem function and biodiversity.


  3. “how species come to be…”

    What drives “species come to be” is what drives all life/organisms to come to be, i.e. a proven successful route, circumstantially evolved culture, that enhanced the RNAs’ constrained energy by the culturally enhanced RNAs’ proliferation, followed with accordingly alternatively spliced expression.

    This is evolution, i.e. enhanced constrained energy to delay-postpone the universal conversion of mass-formats to energy, to the energy that keeps fueling the expansion of the universe. This expansion will be overcome by gravity upon depletion of the universe’s massfuel, and will be followed by empansion for accelerating reverting of energy to mass all the way back to singularity. The universe is an allmass allenergy poles affair.

    Dov Henis
    (comments from 22nd century)

    - It’s culture that modifies genetics, that changes gene’s expression. NOT vice versa.
    - Epigenetics YOK. Alternative splicing is epiDNAtic, not epigenetic.
    - ALL life is RNAs evolution products. RNAs are Earth’s prime organism.


  4. Well, I think the paper is misguiding the conservationists should assess the species as a whole but not to differentiate them as native species and non-native species. I think there should be more scientific data on this topic rather than just arguing about it. In point of view any kind of evaluation caused by nature is not unusual and the species will get used to it as well.


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