David Steen, in his blog "Living Alongside Wildlife," recently interviewed Frank Burbrink on the occasion of the publication of the second edition of the latter's paper proposing that the Florida Cottonmouth (Agkistrodon piscivorus conanti) be elevated to full species status and that the copperheads are actually composed of two species, an eastern A. contortrix and a western A. laticinctus.
The new paper is a rehash of an earlier effort by the same two authors based largely on mitochondrial DNA where they mercifully refrained from actually proposing taxonomic changes pending further investigation. This preliminary paper was discussed HERE several years ago. The new paper actually goes there, proposing a new arrangement of the North American Agkistrodon.
But, be that as it may, this post concerns a curious analogy proposed by Burbrink during the interview (this is Steen summarizing Burbrink's comments):
"Instead of focusing on what their morphology is today, many biologists seeking to differentiate species now try to reveal their past evolutionary paths. If a group of organisms has had a different evolutionary path than another group of organisms, they might be considered different species. And, an effective way to explore evolutionary relationships is to identify the genetic make-up of animals over wide areas. If a group of organisms in one region has different genes than similar organisms in a different region, this is evidence that they can be considered different species.
"Dr. Burbrink gave an analogy: if aliens landed on our planet and could not tell apart all the different kinds of apes, they could take a blood sample from chimpanzees, gorillas, and us, characterize our genes, and see that we are quite different, even if that alien didn’t think so from looking at us. That’s basically what he did for the animal we have been calling the Cottonmouth. He found that there was very little gene flow between the two types of Cottonmouths and, separately, between the two types of Copperheads. . . ."
Dr. Burbrink's "aliens analyzing apes" analogy falls apart when you consider that the genomes of humans and our closest relatives, chimps and bonobos, are 98-99% similar; even gorillas are >90% similar to humans. The only surprises that genetics has provided us that hadn't been previously disclosed by morphology is the fact that humans are more closely related to chimps and bonobos than those species are to gorillas. This means, of course, that a tiny fraction of the genome can be responsible for tremendous differences between even closely related species.
Amazingly however, these few genes that are actually responsible for the differences between species are NOT the ones phylogeneticists typically sequence (most of these highly consequential genes haven't even been identified yet). Consequently, in the case of these hominins (and probably most cases) morphology would be vastly more indicative of relationship than sequencing a few randomly evolving genes, and certainly even more so in distinguishing between hominin species. And certainly equally so in herp species, at least to the extent that they should not be totally ignored.
The entire interview with Burbrink may be read HERE .