The invader’s double edge

15 06 2012

The Ogasawara Archipelago (Bonin Islands,) encompasses several tens of small islands ~ 1000 km from mainland Japan. In 2011, UNESCO declared this archipelago a World Heritage Site. Some regard them as the “Galapagos of the Orient”, owing to their biological singularity, e.g., endemism rates of ~ 50 % of > 500 species of plants, or ~ 90 % of > 100 species of terrestrial snails. Photos show patches of native scrub (left) and introduced sheoak forest (right), close-ups of the two study species Ogasawarana discrepans (left) and O. optima (right), and empty shells with (top right, bottom) and without (top left) rat scars (Courtesy of Satoshi Chiba).

Another great post by Salvador Herrando-Pérez that challenges our views on invasive species (some would do well to heed his words when it comes to species like dingos). I mentioned in his last post that he had just recently submitted his PhD thesis, and now I’m proud to say that it has been examined with no recommended changes required. What a truly rare accolade. Congratulations, Salva.

A blunt instrument of ecological restoration is the elimination of introduced species. However, when introduced species become custodians of native wildlife, a dilemma emerges between re-establishing historical ecosystem conditions or instead, accepting foreign species for the benefits they might also bring.

Right after birth, we all enter a culture where what is ‘good’ or ‘bad’ has already been determined. Later on, if those values remain unchallenged, individuals assume them to be true and act accordingly (which is neither ‘good’ nor ‘bad’ necessarily… it is just so). Science is therefore the only recourse humans have to check such values by  reducing the subjectivity of our judgements about why natural phenomena occur.

But scientists also work in a context of ‘pre-established truths’ (because, believe it or not, most of us are human too). The late Larry Slobodkin referred to our professional biases as ‘reifications’; i.e.,

“…reification consists of accepting a designation as if it has empirical meaning when, in fact, its existence has either never been tested or it has been found empty” (1).

Slobodkin underlined invasive species as an icon of reification. Indeed, people (with and without a scientific background) tend to demonise species that are not native and extremely abundant – experts even debate whether this is another sort of xenophobia (2). Thus, zebra mussels (Dreissena polymorpha), cane toads (Rhinella marinus) or caulerpa algae (Caulerpa taxifolia) are commonly referred to as ‘alien’, ‘invasive’ or ‘noxious’. Technically, we now call them ‘biological pollution’ (3). Such epithets are loaded with moral and pejorative connotations to qualify organisms that affect the range of facets of human well-being (aesthetics, economy, ethics, health). Read the rest of this entry »