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Coffee!!: Desperately seeking unshot wildlife biologist

In “Frogs Evolve Teeth – Again: Mysterious re-evolution challenges evolutionary theory, scientists say”, Christine Dell’Amore (National Geographic News, February 10, 2011) tells us,

Lower-jaw teeth in frogs re-evolved after an absence of 200 million years, a new study says. The discovery challenges a “cornerstone” of evolutionary thinking, according to experts.Of the more than 6,000 species of frogs, only one, a South American marsupial tree frog called Gastrotheca guentheri, has teeth on both its upper and lower jaws. Most frogs have only tiny upper-jaw teeth.

Apparently, G. guentheri has acted in violation of Dollo’s law, according to which traits lost through evolution cannot be regained.

“It’s a very clear case of reacquisition of a lost complex morphological structure, which, according to current thinking, should not be possible.”

Well one thing for sure, that frog’s gotta go. Worse:

“The fact that toothlike structures appear more often than real teeth means that tooth evolution doesn’t automatically occur when the need arises, Yale’s Wagner noted.With that in mind, natural selection – the process by which favorable traits become more common over time within a species – is “not enough to explain” why the marsupial tree frog regained its lower teeth.

“I can confidently say that we don’t know,” Wagner said. “It’s an extremely interesting question.”

A friend wonders, “Did this guy get shot for saying this?”

I dunno. Anyone seen him around lately?

Texas Darwin lobby, please note. Another subject to cross off the list of what students can hear about.

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3 Responses to Coffee!!: Desperately seeking unshot wildlife biologist

  1. I’m shocked! I was led to believe that evoluton could do everything. After all, if no other theory is allowed, evolution has to true.

    If evolution can turn a land mammal into a whale, why can’t evolution re-evolve teeth?

  2. of note from article; ‘An alternate theory is that lower-jaw teeth were lost in hundreds of other frog species but not G. guentheri.’

    Any bets?

  3. notes;

    Response from Ralph Seelke to David Hillis Regarding Testimony on Bacterial Evolution Before Texas State Board of Education, January 21, 2009
    Excerpt: He has done excellent work showing the capabilities of evolution when it can take one step at a time. I have used a different approach to show the difficulties that evolution encounters when it must take two steps at a time. So while similar, our work has important differences, and Dr. Bull’s research has not contradicted or refuted my own.
    http://www.discovery.org/a/9951

    Reductive Evolution Can Prevent Populations from Taking Simple Adaptive Paths to High Fitness – Ann K. Gauger, Stephanie Ebnet, Pamela F. Fahey, and Ralph Seelke – 2010
    Excerpt: When all of these possibilities are left open by the experimental design, the populations consistently take paths that reduce expression of trpAE49V,D60N, making the path to new (restored) function virtually inaccessible. This demonstrates that the cost of expressing genes that provide weak new functions is a significant constraint on the emergence of new functions. In particular, populations with multiple adaptive paths open to them may be much less likely to take an adaptive path to high fitness if that path requires over-expression.
    http://bio-complexity.org/ojs/.....O-C.2010.2

    Dollo’s law and the death and resurrection of genes
    ABSTRACT: Dollo’s law, the concept that evolution is not substantively reversible, implies that the degradation of genetic information is sufficiently fast that genes or developmental pathways released from selective pressure will rapidly become nonfunctional. Using empirical data to assess the rate of loss of coding information in genes for proteins with varying degrees of tolerance to mutational change, we show that, in fact, there is a significant probability over evolutionary time scales of 0.5-6 million years for successful reactivation of silenced genes or “lost” developmental programs. Conversely, the reactivation of long (>10 million years)-unexpressed genes and dormant developmental pathways is not possible unless function is maintained by other selective constraints;
    http://www.pnas.org/content/91.....l.pdf+html

    i.e. the loophole to Dollo’s law is that if the gene’s function is maintained by other ‘selective constraints’, which is not unlikely in that gene sequences are found to be encoded with multiple layers of parallel information, then the reactivation of a gene can occur after 10 million years. Dollo’s ‘Law’, as far as rigorous science is concerned would be better classified as a ‘general rule of thumb’ for the deterioration we witness for ‘kinds’ within the fossil record.

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