September 13, 2004 | David F. Coppedge

Salamander Genes Give Darwinists a Wake-Up Call

A press release from UC Berkeley says that the evolutionary family tree of salamanders, once thought secure, has been turned topsy-turvy by a study of the genes.  The opening paragraph is reminiscent of an irritating alarm clock going off in a comfy bedroom:

Biologists take for granted that the limbs and branches of the tree of life – painstakingly constructed since Linnaeus started classifying organisms 270 years ago – are basically correct.  New genetic studies, the thinking goes, will only prune the twigs, perhaps shuffling around a few species here and there.
    Hence the surprise when a new University of California, Berkeley, study of the largest family of salamanders produced a genetic family tree totally inconsistent with the accepted classification, which is based primarily on physical features. (Emphasis added in all quotes.)

To be sure, the study did not put salamanders in with birds or sharks or something that radical.  But the results were radical enough to make evolutionists seriously consider a radical interpretation: that some lineages lost a function and then re-evolved it:

Salamanders formerly classified together because of similar characteristics, such as a tail that breaks at only one spot as opposed to anywhere when stressed, now appear not to be close relatives at all.  And salamanders that go through an aquatic larval stage are scattered about on different branches instead of grouped on one limb of the tree: Apparently some salamander lineages lost the larval stage and then reacquired it again.

“The results were stunningly different than what we anticipated,” said David Wake, an expert on salamanders at the university.  The study conducted by one of his graduate students found major upsets in the phylogenetic tree determined from mitochondrial DNA analysis.  The student, Rachel Mueller, learned a lesson: “this does tell us that, when reconstructing evolutionary relationships, you have to be careful which morphological features you assume are conservative and haven’t evolved much, and which you think are likely to have changed over time.”

The new family tree shows, however, that some terrestrial salamanders regained their larval stage after moving back to the water.  This may have happened in three separate lineages of Plethodontids [the largest family of salamanders], which is surprising for a seemingly complex feature biologists have assumed arose just once, very early in the history of salamanders.

Wake also has found that the three very different types of salamander tongues, some which are short and stubby and some that can be flung out nearly the length of the salamander’s body, “have evolved several times in different lineages.”  The new genetic data, published in PNAS,1 tend to confirm that, he said.
    Meanwhile, in Science Sept. 10,2 Elizabeth Pennisi says James Hanken of Harvard has proposed, based on genetic studies, that a certain line of miniature salamanders from Mexico acquired upper teeth independently four times.  He defended this view against critics at the 7th International Congress of Vertebrate Morphology in Boca Raton, Florida last month:

Some of Hanken’s colleagues question his interpretation, noting that the common wisdom holds that once a trait disappears from a group of organisms, it rarely resurfaces.  Hanken’s conclusion is “something that’s hard to defend,” says Ann Huysseune of Ghent University in Belgium.  But Hanken argues that these small vertebrates must have had a lot of evolutionary tricks up their sleeves in order to survive tough times.  He points to the success that small animals in general have had after mass extinctions and attributes that to their ability to rapidly change and adapt.
    Thorius species, he thinks, may have retained the capability of making upper teeth, even if their tooth-building program became short-circuited.  The reappearance of upper teeth in the four salamander species, says Hanken, “offers an example of latent developmental potentialities that reside within living species but which may not be manifest or expressed until far into the future.”


1Mueller, Wake et al., “Morphological homoplasy, life history evolution, and historical biogeography of plethodontid salamanders inferred from complete mitochondrial genomes,” Proceedings of the National Academy of Sciences USA, 10.1073/pnas.0405785101, published online Sept. 13, 2004.
2Elizabeth Pennisi, “Tiny Salamanders Show Their Teeth,” Science, Vol 305, Issue 5689, 1396-1397, 3 September 2004, [DOI: 10.1126/science.305.5689.1396b].

How long must we hold onto an outmoded hypothesis when it continually forces its adherents to believe absurd things?  To get a larval stage or a ballistic tongue once is astronomically improbable.  How can anyone believe it happened multiple times?  And to believe that something as complex as the suite of developmental genes for a set of teeth can just wait inert in a genome for the right time far into the future, without being eliminated by natural selection, violates Darwin’s own principles.  Salamanders don’t have sleeves.  How can they hide tricks up them?  If any problem in evolution can be explained away by magic tricks, it is not science.  The genetic data are not proving Darwin right, so Chuck his theory.  Wake up; it was only a bad trip (see 09/12/2004 commentary).

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Categories: Terrestrial Zoology

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