Home » Darwinism, Natural selection, News » Is this study of salamander evolution a spoof? You decide.

Is this study of salamander evolution a spoof? You decide.

pregnant female salamander/Steven Brady

From “Road Runoff Spurring Spotted Salamander Evolution” (ScienceDaily, Feb. 1, 2012), we learn,

Spotted salamanders exposed to contaminated roadside ponds are adapting to their toxic environments, according to a Yale paper in Scientific Reports. This study provides the first documented evidence that a vertebrate has adapted to the negative effects of roads apparently by evolving rapidly.

How are they evolving? As a result of contact with road salt, they

have higher mortality, grow at a slower rate and are more than likely to develop L-shaped spines and other disfigurements. In roadside ponds, only 56 percent of salamander eggs survive the first 10 weeks of development, whereas 87 percent survive in the woodland ponds. As roadside ponds become more toxic, the surviving salamanders may develop a genetic advantage over their counterparts living in woodland ponds.

It’s not clear what advantages deformity and mortality due to excess salt provide, or why we should regard them as evidence for evolution. In any event, what is predicted to happen if the county decides to use more sand and less salt, for road traction? Will the salamanders de-evolve rapidly to more normal development and mortality rates?

We’re told that, when raised together with salamanders from cleaner ponds, the salt-tolerant salamanders “actually do better – substantially better.” Perhaps because they are the tough 56% to begin with, though details are not provided.

Puzzling:

“While the evolutionary consequences of roads are largely unknown, we know they are strong agents of natural selection and set the stage for fast evolution,” said Steven Brady, the study’s author and a doctoral student at the Yale School of Forestry & Environmental Studies.

How do we know that roads are strong agents of natural selection if their evolutionary consequences are unknown? In any event, how long have roads actually been around? And how long have life forms been around? Is there nearly enough evidence to be sure of roads’ role in evolution?

Has any life form developed and passed on a complex new mechanism as a result of run-ins with roads? Formed a new species in consequence?

Salt aside, one obvious problem with any “fast evolution due to roads” thesis is summed up in two words: Road kill. The survivors of the species who mate may not be the ones with so much experience of roads …

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7 Responses to Is this study of salamander evolution a spoof? You decide.

  1. “what is predicted to happen if the county decides to use more sand and less salt, for road traction? Will the salamanders de-evolve rapidly to more normal development and mortality rates?

    We’re told that, when raised together with salamanders from cleaner ponds, the salt-tolerant salamanders “actually do better – substantially better.” Perhaps because they are the tough 56% to begin with, though details are not provided.”

    Exactly. This is like Darwin’s finches where one environment encourages birds with genes for harder beaks or longer beaks to survive and then in a different environment, the opposite happens. This is a back and forth process with no net change in the birds. The finches are still finches and we don’t see any birds with abnormally long beaks or abnormally small beaks – just within the normal range.

    Natural selection works with the genes ALREADY PRESENT and selects for those genes that most enable survival in that particular environment, but it is not creating new genes. These salamanders are still salamanders. Perhaps if isolated long enough, this particular salamander population would end up with permanently crooked tails, if all the genes for straight tails are lost. Evolution via lost genes is not the kind of change evolutionists need to prove their point. Even creationists believe in this type of evolution. In fact, we believe that almost all the evolution we see happening today is this type of evolution. You will never get an astronaut from an amoeba if genes are continually being lost or damaged, even if there are insignificant side benefits to the changes from time to time.

  2. tjguy,

    Natural selection works with the genes ALREADY PRESENT and selects for those genes that most enable survival in that particular environment, but it is not creating new genes.

    Besides wishful thinking, how do you know that the genes and alleles were all already present?

  3. UHHH, because that is what the evidence states:

    In fact, the loss of morphological traits over time, for all organisms found in the fossil record, was/is so consistent that it was made into a ‘scientific law’:

    Dollo’s law and the death and resurrection of genes:
    Excerpt: “As the history of animal life was traced in the fossil record during the 19th century, it was observed that once an anatomical feature was lost in the course of evolution it never staged a return. This observation became canonized as Dollo’s law, after its propounder, and is taken as a general statement that evolution is irreversible.”
    http://www.pnas.org/content/91.....l.pdf+html

    A general rule of thumb for the ‘Deterioration/Genetic Entropy’ of Dollo’s Law as it applies to the fossil record is found here:

    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

    No Positive Selection, No Darwin: A New Non-Darwinian Mechanism for the Origin of Adaptive Phenotypes – November 2011
    Excerpt: Hughes now proposes a model he refers to as the plasticity-relaxation-mutation (PRM) model. PRM suggests that adaptive phenotypes arise as follows: (1) there exists a phenotypically plastic trait (i.e., one that changes with the environment, such as sweating in the summer heat); (2) the environment becomes constant, such that the trait assumes only one of its states for a lengthened period of time; and (3) during that time, deleterious mutations accumulate in the unused state of the trait, such that its genetic basis is subsequently lost.
    ,,, But if most adaptations result from the loss of genetic specifications, how did the traits initially arise? One letter (Chevin & Beckerman 2011) of response to Hughes noted that the PRM “does not explain why the ancestral state should be phenotypically plastic, or why this plasticity should be adaptive in the first place.”
    http://www.evolutionnews.org/2.....52941.html

    A. L. Hughes’s New Non-Darwinian Mechanism of Adaption Was Discovered and Published in Detail by an ID Geneticist 25 Years Ago – Wolf-Ekkehard Lönnig – December 2011
    Excerpt: The original species had a greater genetic potential to adapt to all possible environments. In the course of time this broad capacity for adaptation has been steadily reduced in the respective habitats by the accumulation of slightly deleterious alleles (as well as total losses of genetic functions redundant for a habitat), with the exception, of course, of that part which was necessary for coping with a species’ particular environment….By mutative reduction of the genetic potential, modifications became “heritable”. — As strange as it may at first sound, however, this has nothing to do with the inheritance of acquired characteristics. For the characteristics were not acquired evolutionarily, but existed from the very beginning due to the greater adaptability. In many species only the genetic functions necessary for coping with the corresponding environment have been preserved from this adaptability potential. The “remainder” has been lost by mutations (accumulation of slightly disadvantageous alleles) — in the formation of secondary species.
    http://www.evolutionnews.org/2.....53881.html

    Dollo’s Law was further verified to the molecular level here:

    Dollo’s law, the symmetry of time, and the edge of evolution – Michael Behe
    Excerpt: We predict that future investigations, like ours, will support a molecular version of Dollo’s law:,,, Dr. Behe comments on the finding of the study, “The old, organismal, time-asymmetric Dollo’s law supposedly blocked off just the past to Darwinian processes, for arbitrary reasons. A Dollo’s law in the molecular sense of Bridgham et al (2009), however, is time-symmetric. A time-symmetric law will substantially block both the past and the future.
    http://www.evolutionnews.org/2.....f_tim.html

    further confirmation;

    Evolutionary Adaptations Can Be Reversed, but Rarely – May 2011
    Excerpt: They found that a very small percentage of evolutionary adaptations in a drug-resistance gene can be reversed, but only if the adaptations involve fewer than four discrete genetic mutations. (If reverting to a previous function, which is advantageous, is so constrained, what does this say about gaining a completely novel function, which may be advantageous, which requires many more mutations?)
    http://www.sciencedaily.com/re.....162538.htm

    Some Further Research On Dollo’s Law – Wolf-Ekkehard Lonnig – November 2010
    http://www.globalsciencebooks......)1-21o.pdf

    Further facts that conform to the principle of genetic entropy:

    “According to a ‘law’ formulated by E. D. Cope in 1871, the body size of organisms in a peculiar evolutionary lineage tends to increase. But Cope’s rule has failed the most comprehensive test applied to it yet.”(body sizes tend to get smaller rather than larger)
    Stephen Gould, Harvard, Nature, V.385, 1/16/97

    “The sweep of anatomical diversity reached a maximum right after the initial diversification of multicellular animals. The later history of life proceeded by elimination not expansion.”
    Stephen J. Gould, Harvard, Wonderful Life, 1989, p.46

    Further facts that conform to the principle of genetic entropy:

    “According to a ‘law’ formulated by E. D. Cope in 1871, the body size of organisms in a peculiar evolutionary lineage tends to increase. But Cope’s rule has failed the most comprehensive test applied to it yet.”(body sizes tend to get smaller over time rather than larger)
    Stephen Gould, Harvard, Nature, V.385, 1/16/97

  4. Eh. I haven’t bothered to read, but I assume from the summary that they didn’t bother to rule out gene expressions. And if the strongest statement is “may develop a genetic advantage” then I take as given that they never bothered with the little things. Like bean-counting and standard deviations.

  5. Is this post a spoof?

    We’re told that, when raised together with salamanders from cleaner ponds, the salt-tolerant salamanders “actually do better – substantially better.” Perhaps because they are the tough 56% to begin with, though details are not provided.

    The 56% figure refers to the pooled mean of hatchling survival in roadside ponds. If you only consider the hatchlings that were from the original roadside pond population, survival is over 60%. Also, there was almost no prior selection in these cohorts, as the transplanted embryos were exposed a minimal amount of time (<48 hr) to their original environments, the embryos from both sources had nearly the same chances to acclimatise. So I don’t get what you mean, if anything, by saying that it was “because they are the tough 56% to begin with”.

    There’s a link to the paper at the end of the article. You can read the full text with all the details for free.

    How do we know that roads are strong agents of natural selection if their evolutionary consequences are unknown?

    Because the hatchlings from the clean ponds had a 25% higher mortality in the roadside ponds than the hatchlings that had time to adapt in those ponds.

    In any event, how long have roads actually been around?

    According to the paper: “[A]erial imagery suggests that four of the five roaded sites within this study were first paved 44 to 58 years prior (with the fifth at least 75 years prior)”.

    And how long have life forms been around?

    About 3.4 billion years ago.

    Is there nearly enough evidence to be sure of roads’ role in evolution?

    Most likely, as it doesn’t seem to be a case of maternal effects. Anyway, I don’t think this is anything spectacular. I wonder why you freak out about this simple study. Do you deny any natural selection ever happens at all?

  6. I haven’t bothered to read

    Neither did Denyse.

    but I assume from the summary that they didn’t bother to rule out gene expressions.

    Why would they want to rule out “gene expression”? I’m not even sure what do you think “gene expression” means.

    Here’s the bean-counting.

  7. I missed this bit:

    Salt aside, one obvious problem with any “fast evolution due to roads” thesis is summed up in two words: Road kill. The survivors of the species who mate may not be the ones with so much experience of roads …

    Now, that‘s a puzzling statement.

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