Non-Native or Invasive? The Difference Between Friend and Foe

At some point in the 1930s, colonies of Solenopsis invicta entered the United States stowed away on ships via Mobile, Alabama. Eighty years later, these red fire ants have made their way to every corner of the southern United States, waiting for their next opportunity to ruin a picnic. This is hardly an endearing case for the organisms we classify as “invasive species.”

Fire Ants have been considered a pest in the United States since their arrival in the 1930s. Meanwhile in Hawaii, the Japanese White-Eye acts as one of the major dispersers of native plant seeds. [2, 3]

Fire Ants have been considered a pest in the United States since their arrival in the 1930s. Meanwhile in Hawaii, the Japanese White-Eye acts as one of the major dispersers of native plant seeds. [2, 3]

For a time, the scientific record documenting invasive species was overwhelmingly negative, with an “emphasis on documenting the negative economic and biological effects of non-native species.”1 However, there are two sides to each coin, and in an article in Conservation Biology, authors Schlaepfer, Sax, and Olden—associated with the State University of New York, Brown University, and the University of Washington, respectively—reassess the historical view of invasive species and highlight their positive roles, consequences, and applications. Many of the once “invasive” species, upon realization of their positive ecological roles, earn the replacement moniker of “non-native” species in the study.

The scientists analyzed information from well over 100 scientific articles and studies examining the effects of non-native species—both those introduced intentionally and unintentionally due to a variety of circumstances. While we often think of invasive species as “intruders,” the authors explore and categorize the current and potential future roles of non-native species in ecosystems, and the results are surprisingly positive.

Non-native species around the world are fulfilling valuable roles in their new homes, from providing food and shelter to native species, to acting as substitutes for extinct taxa. The authors even cite a 2007 study by Foster and Robinson detailing non-native birds’ role in Hawaii as the primary distributors of the native plants’ seeds and fruits.1 Other examples of positive impacts from butterflies, snails, oysters, and even tortoises are noted in the study and summarized by the authors.1

Granted, many invasive species, including some on the list, have negative consequences on parts or all of the ecosystems which they inhabit. However, to say that they are all bad would be quite inaccurate. With almost five positive examples (4.167 to be precise) for each negative example, these so-called “intruders” seem to be much more amicable than previously believed

From these current observations regarding non-native species, the authors extrapolate to the future, considering the possibilities associated with non-native species—possibilities which include functioning in “rapidly changing ecosystems” and leading to “novel evolutionary lineages.”1

Looking at the prospect of humans utilizing non-native species on a grand scale, it begs the question, “Are we playing God?” It is a dramatic stance to take. However, manipulating our environments and thrusting new species into new environments is not an exact science, and one can almost expect unexpected outcomes to arise.

Many can and will cite examples and case studies detailing the destruction an invasive species has had on its environment. Many will also cite examples showing a logically sound plan backfiring, of organisms acting in ways never anticipated. Clearly, though, it hasn’t all been bad. With sound science and thought-out plans to minimize these risks, isn’t it fair to say that trying to help ecosystems thrive is worth more than the fear of failing? Programs of this nature have proven beneficial before, and may likely prove themselves to be solutions to some of our most pressing conservation issues in the future.

As we work towards preserving our world, we learn with each attempt at progress. The incorporation of using non-native species to revitalize suffering or desolate ecosystems in a variety of ways offers a chest full of opportunities for scientists and civilians alike to positively impact the world.


 Works Cited:

 1Schlaepfer, Martin A., Dov F. Sax, and Julian D. Olden. “The Potential Conservation Value of Non‐Native Species.” Conservation Biology 25.3 (2011): 428-437.

2“Fire ants02”. Licensed under Public Domain via Commons –

3“Japanese White-eye” by Trisha Shears from Louisville, Kentucky, United States – Japanese White Eye Image. Licensed under CC BY-SA 2.0 via Commons –




This entry was posted in Conservation Biology Posts, Conservation Editorials 2015. Bookmark the permalink.

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