Modular (Mosaic) Evolution according to Wikipedia

The following is a direct lift from the Wiki article on Modular Evolution with critical comments added in red.

Redirected to:
Mosaic evolution (or modular evolution) is the concept that evolutionary change takes place in some body parts or systems without simultaneous changes in other parts.[1] Another definition is the “evolution of characters at various rates both within and between species”.[2]408 Its place in evolutionary theory comes under long-term trends or macroevolution.[2]

By its very nature, the evidence for this idea comes mainly from palaeontology. It is not claimed that this pattern is universal, but there is now a wide range of examples from many different taxa. Some examples:

Unfortunately this narrow and hopeful view ignores the fact that paleontologists can identify an australopithecine from its skull and teethvertebrae and other body parts. So, no modular evolution here. 

And yet paleontologists can identify Archaeopteryx by the pelvis, skull, tail, etc, whether wings or feathers are present or not. The differences are present, even if subtle. So, no modular evolution here. 

  • Meadow voles during the last 500,000 years.[6]

This example is reported  at the population level. Nothing here strong enough to differentiate one species from another. 

Unfortunately, Darwinopterus was not the transitional taxon between the long tails and short tails when you add more taxa to your analysis. Darwinopterus was an evolutionary dead end with no Cretaceous descendants. Sure it had a long skull and long neck, like pterodactyloids. But anurognathids had a short tail like pterodactyloids and only Andres thinks they were transitional. So, no modular evolution here. Convergence, yes!

Evolution from tiny four-toed pre-horses to large one-toed modern horses indeed took place over many millions of years. Certain traits occurred simultaneously. Others waited until later. So, no modular evolution here. 

Not sure what the reporter has in mind here, but certainly there were several clades that demonstrate convergence. Mammal experts are famous for being able to identify their specimens from a few teeth alone. So while other parts were evolving, so were the teeth. So, no modular evolution here. 

If anyone can provide an example of modular evolution in vertebrates, please bring it to the attention of the Wikipedia author of this article. If modular evolution were indeed present, paleontologists would be confounded by one end of the body not matching the other. Phylogenetic analysis usually takes care of all such problems.

And convergence is out there ready to trip you up if you’re not careful.

3 thoughts on “Modular (Mosaic) Evolution according to Wikipedia

  1. Ok I’ve already said much of this, but since you seem incapable of listening I’m just going to keep posting it so that others who read your blog are not misinformed.

    Firstly. Modular Evolution does NOT mean one part changes while another does not. It does NOT mean that a palaeontologist should not be able to identify a specimen from only a part of it. It does NOT mean that different traits can’t appear at the same time in different parts of the body.

    Modular Evolution is the recognition that certain traits are functionally and/or developmentally linked and so are more likely to change as a unit. This leads to changes at different rates in different parts of the body. It does not stop changes in certain parts. All you’ve done in this post is construct a straw man to argue against. Every argument you’ve made here is irrelevant to modular evolution.

    So, with that now understood, lets go through your arguments.

    Australopithecenes: “Unfortunately this narrow and hopeful view ignores the fact that paleontologists can identify an australopithecine from its skull and teeth, vertebrae and other body parts. So, no modular evolution here.”
    Irrelevant. Modular evolution in australopithecenes is about the fact that the forelimb, hindlimb and dentition are different functional units and so each unit evolved at a different rate. This does not mean that one part stopped evolving while other parts continued, and this does not preclude useful characters from appearing in all.

    Archaeopteryx: “And yet paleontologists can identify Archaeopteryx by the pelvis, skull, tail, etc, whether wings or feathers are present or not. The differences are present, even if subtle. So, no modular evolution here. ”
    See above

    Meadow voles “This example is reported at the population level. Nothing here strong enough to differentiate one species from another.”
    What, are you trying to argue that different populations can’t show evolutionary differences?? There are thousands of examples of different populations of the same species evolving differences, and those differences will evolve with the same processes as interspecific differences. That includes modular evolution.

    The pterosaur: this is about disagreements of phylogeny, not an argument for or against modular evolution

    The Horse: “Certain traits occurred simultaneously. Others waited until later. So, no modular evolution here.”
    Modular evolution does not preclude this from Happening. It merely indicates certain characteristics are more likely to appear together than separately because they are functionally linked. An irrelevant comment.

    Mammals, no specific examples given by either side (although there was that example I gave you last time)

    My second Point is yes, one can identify specimens from only partial fragments. However, not only are such identifications not proof against modular evolution (see above) but these identifications become less reliable. Moreover Phylogenetic Analysis does not help here, in spite of your hopeful assertion that “phylogenetic analysis usually takes care of all such problems.” The work of Sansom, Wiens and Pol (references below) show how big a problem fragmentary specimens are for phylogenetic analysis, especially with fossils. The simple fact, shown by these works, is that the more fragmentary the specimens, the more likely the misidentification. That is why so many shoddy species are synonymised with others following the discovery of new material.

    I will finish by saying that nit picking specific examples does not alter the hundreds of studies into the occurence and the developmental and genetic causes of modular evolution. What you have here is a desperate attempt to save face over your repeated past assumptions about modular evolution

    References

    Sansom, R. & Wills, M. 2014. Fossilization causes organisms to appear erroneously primitive by distorting evolutionary trees. Scientific reports (3): 2545

    Pol, D. & Escapa, I. 2009. Unstable taxa in cladistic analysis: identification and the assessment of relevant characters. Cladistics (25): 515-527

    Wiens, J. 2003. Missing data, incomplete taxa, and phylogenetic accuracy. Systematic Biology (52): 528–538

  2. Neil, There is something you’re missing here. Modular evolution, according to the authors of the Darwinopterus papers and according to the author of Wikipedia means exactly that, that one part changes while another does not. I am capable of listening, but you need to see this difference. I agree with you and the two of us disagree with the authors of the Darwinopterus paper and the Wiki article. I have no problem with modules evolving together, as in the pelvis, knees and feet of a hominid. Or the teeth and belly of herbivores. Or the tail and dorsal fins of aquatic animals. I do have a problem with the front half of any animal evolving first and the back half evolving later, as the authors of the Darwinopterus paper contend. That there were so few examples of modular evolution portrayed in the Wiki article suggest that those were “just so” stories and happy accidents. Your beef is with them, not me.

    • But the point I’m making is that the examples in wiki ARE valid examples Modular Evolution. Your repeated Statement “No Modular Evolution here” is unjustified since your arguments against them being Modular Evolution are incorrect. Perhaps wiki does not explain adequately why these are examples of Modular Evolution, and gets a couple of the details wrong, but these are most definitely valid examples and not “just so” stories.

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