Blurred Lines: Aspidoscelis neavesi

There was a song that came out a couple of years ago about the blurred lines of consent, and while I am NOT a fan of the song, I do think that one could write a hilarious parody of it about species concepts.  (We should do more of these biological parodies of popular songs!)

I’ve written at length about the fallibility of the various concepts we use to delineate different species. An article in the New York Times last week brought this problem back to my attention.  A group of scientists studying whip lizards in the southwestern United States have recently produced what is heralded as a new species in the lab.

The new species(?) Aspidoscelis neavesi, is a hybrid.  But it’s not just a hybrid.  It’s a hybrid of a hybrid that reproduces solely by parthenogenesis.  It has four sets of chromosomes, three of which are from the wild species Aspidoscelis exsanguis while the fourth is from the wild species Aspidoscelis inornata (for more details on this, see Carl Zimmer’s article in the NY Times).

And it’s difficult to know how to feel about this.

I don’t mind that the species was produced in a laboratory; as the article mentions, the four chromosome hybrid likely exists in low numbers in the wild.  And it is not as problematic that the species is parthenogenic (there are numerous parthenogenic species out there), although if it’s exclusively parthenogenic, it is an evolutionary dead end.

My problem with calling this a new species is that the lines between these different whiptail species are becoming very blurry indeed.  The two wild species seem to hybridize regularly, and when should the hybrid offspring be called a new species (It was unclear to me whether the hybrid with three sets of chromosomes was also called its own species.) Where do we draw the line?  I agree with David Hillis (who is quoted in the article) that these organisms should almost have a new name “hybrid clones” or similar.

Still, cute lizard.

Photo by Peter Baumann

Aspidoscelis neavesi, Photo by Peter Baumann

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