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To be, or not to be, which species? Why question?

22 Sep

Over the past several years I have participated in the genetic and taxonomic debates over the Red wolf: is it Canis lupus (wolf)? Canis latrans (coyote)?  Canis rufus (current classification)? Or a hybrid?

Depending on which author’s paper you read, the general consensus is that the animal shares more genetic similarity with the coyote than wolf. To complicate the game, a few genetic markers associated with (note my avoidance of ‘unique to’)  the red wolf can be found in a sub-population of the timber  wolf, most notably the Great Lakes or Algonquin wolf.

The typical argument against introgression of the two wild canid species, C. lupus and C. latrans, is behavioral boundaries between them. Under normal circumstances, the two species do not tolerate each other and will not mate to form hybrid offspring. When they are sympatric (when their territories overlap), wolves usually kill coyotes or they just avoid each other.

However, a group of geneticists hypothesize that despite traditional behavioral and geographical boundaries that usually prevent introgression between species, these very boundaries are plastic. In other words, they may fail and individuals of both species may mate and produce viable offspring.

A scenario of this transgression might be in a geographical area that borders territories of both species. If resources are severely limiting, such as during a long drought cycle, a few individuals of each species may mate due to poor mating opportunities within their own species.

Another scenario is more common today: when human land use encroaches upon and shrinks traditional habitats, forcing trespass from one species into territory of the other. This is the primary explanation given for the increase of the current  ‘coywolf’ population in the northeastern US.

As one geneticist posits, such introgression may have occurred more than once, especially in an arid region, such as the southwestern area of the red wolf’s former territory: Texas. After several generations of backcrossing and/or admixture with coyotes, isolation of this growing population could conceivably be on the way to speciation, resulting in the historical  and extant Canis rufus.

Now, here lies the question: is this animal a species? Or a sub-species? Is it ‘wolf’? Is it ‘coyote’? Or is it a hybrid? And this is when the poor animal falls into the vortex of the ‘species concept’ debate. And possibly one of life or death.

Tonight I reread a paper published in 2006 and that was once used as a focal topic paper in a journal club session: “On the failure of modern species concepts”, by Jody Hey (Trends in Ecology and Evolution, vol. 21, No. 8). An excellent paper that stirred a three-hour debate between eight students and monitors. Shame on me for forgetting the final two paragraphs (‘Lessons on the method of multiple concepts’).

“Definitions cannot be forced to serve the arbitration of entities that are truly ambiguous. The fact is that species are hard to identify for a variety of reasons related to the various ways that they can be indistinct and no criterion that presumes to delineate natural boundaries can overcome this.

As scientists we should not confuse our criteria for detecting species with our theoretical understanding of the way species exist. Detection protocols are not concepts. This point would be child’s play if we were talking about electrons or disease agents, but because real species are so difficult to study, and because our best understanding of them includes their often being truly indistinct, we have had trouble separating the detection criteria from our more basic ideas on the existence of species.”

Right now, the fate of the red wolf in large part revolves around whether or not it is classified as a true species, sub-species, or a hybrid. The Endangered Species Act does not recognize and therefore does not include hybrids for protection from extinction. Both government agencies, policy administrators and scientists are still embroiled in the vicious vortex of yea or nay. Nor can the biologists agree on how the species concept applies to a possible animal caught in the cycle of speciation.

I am a victim of my own Trickster antics of playing in the ‘species concept’ debate. Tonight this is resolved and I am absolved: it doesn’t matter which species the red wolf is tagged with. It doesn’t matter if it is a hybrid or not. In fact, as a hybrid it’s protection and conservation is even more important. We have the opportunity to watch and learn what happens during the course of a mammalian hybrid as it continues its course of speciation.

May the Red wolf howl and carry on safe from human impact and intervention other than a helping hand for protection from human-caused anhilation. Perhaps you can teach us humans humility. Especially us scientists.

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