A Question about Evolutionary Theory

Punctuated Equilibrium

Incl. intelligent design, belief in divine creation

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Re: A Question about Evolutionary Theory

#21  Postby susu.exp » Oct 28, 2014 5:16 pm

epepke wrote:Yes, it was about emphasis, but I found that one quite powerful. By rephrasing things in terms of gene selection, it clarifies by other means what is muddled in the mind by being exposed to the idiot and handwaving group selection or the only vaguely hanging on kin selection. Even though, of course, there is no actual solid meaning of the word "gene," as approximate fictions go, it's pretty useful for brains. You can think in terms of counting them, and you can imaging them conferring survival benefits overall to a collections of individuals with them even if one or two have a really bad day. It makes sense.


A lot of this is bollocks. Dawkins mainly popularized the views of Williams and one of the things that gets lost in his treatment is what a gene is in a Williams sense.

epepke wrote:Probably the closest Gould came to saying something insightful was the talk about spandrels. This is sort of interesting and can inform modeling approaches. However, it's fairly minor. No, most of the beneficial forms probably aren't spandrels. The eye and all of it's intermediate forms probably were always about seeing, probably in all of the few score cases in which it evolved. Sure, it's an interesting and inspiring idea, but the 45 minutes or so he spent explaining it when I saw him in person, I could have been just as happy with a GameBoy or something. And there's always the risk of going too far in a minor direction.


I think you are missing the point of the spandrels idea, which is mainly about the fact that traits constrain other traits. If you had a rectangular organism then you have 3 traits:
width
length
area
Now, given any two of these the third one can be calculated. You can't vary it without changing one of the others. Gould and Lewontins point is that some ultra-adaptionists infer from NS, that all 3 of these could be optimal, when usually there'd be trade-offs. That's the key to the spandrels idea (and the additional idea that future adaptations can make use of the existing traits).

As far as PE goes, you misrepresent it when you state:
epepke wrote:. Dawkins was the one who kept going on about how gradualism wasn't the same as constant speedism, which is an excellent point. Gould, however, behaved as if PE were something newly discovered, amazing, and qualitatively different.


Here's PE vs. PG in a plot:
Image
The blue line is gradualism, the red line is punctuated equlibrium. No one ever claimed gradualism as having constant rates. Fishers geometrical argument is what underlies PG and it has a distribution of rates that is unimodal, with a peak close to 0 and - and that's very important - independent of time frame. When you look at modern populations they conform to this distribution. However if you look at the fossil record with time scales in the 10s of million years, you get a distribution looking like the red line. That's not something you would expect and it was discovered by Eldredge and Gould.

And to go back to your first post:
epepke wrote:Gould was popularly influential. However, his ideas weren't taken very seriously at all outside the United States. At best they were considered a minor wrinkle. It did seem to me that they were a minor wrinkle, and Gould overstated the importance of the idea.


I call BS. Yes, initially it had little effect outside of the US, but that was because paleontology in most of the world had become a helper discipline for geology and the idea that you could use fossils to study evolution had almost vanished from the discipline. Gould was one of a handful of paleontologists who were interested in biology and these had labs that produced the next generation of people in the field. As paleobiology grew it spread around.

It's also worth noting that Goulds Ontogeny and phylogeny is one of the defining early works of evo-devo, that his contribution to the MBL papers (all of which included Gould and David Raup, some other authors would join some of them) was important and that he did help to bring some interesting ideas to the center of attention in the field (Stanleys species selection, McSheas work on passive trends, the early work on impact induced mass extinctions).

epepke wrote:There's also the possibility, at which some scoff, that PE was ideologically motivated. Gould was an outspoken Marxist, and he was uncomfortable with the idea that competition was important in evolution. I think there might be something to this idea, though it's hard to read the mind of a dead person.


Let me scroff. The Marxist view of history, historical materialism, is deterministic and denies agency. History is produced by class struggles, with individual actors unable to control things. Goulds view of the history of life is about the polar opposite. It's stochastic, it stresses contingency and interestingly puts competition at a less central position than some others.
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Re: A Question about Evolutionary Theory

#22  Postby Calilasseia » Oct 31, 2014 9:02 pm

Darwinsbulldog wrote:
Spearthrower wrote:
Zadocfish2 wrote:As I read some of the materials linked to from this site, namely this one: http://corior.blogspot.com/2006/02/part ... ution.html . In it, it mentions a fact that I would assume is very common in Creationist literature: quote-mining scientists arguing about the differences between Punctuated Equilibrium vs Gradual Descent, and putting forth that proponents of the latter are denying evolution as a whole.

Now, to be honest, as much as I love biology and evolutionary biology as a whole, I mostly only know anything about the Gradual Descent model. To better understand what is being discussed in this article and others, and as a reference for any Creationist users this site may have, can someone explain or post a link explaining how the Punctuated Equilibrium model is thought to work?



Odd! Usually Creationists leap on punctuated equilibria as scientific jargon for the days of creation! :)

Punctuated equilibrium just means that species will exhibit little morphological change over long periods of environmental stasis, but will change rapidly, geologically speaking, when encountering new niches or facing new environmental challenges.

Creationists willfully misinterpret this along the lines of Richard Goldschmidt's 'Hopeful Monster', where dramatic evolutionary changes occur in just one generation - think Crocoducks. Basically, Creationists manage to simultaneously argue that this pokemon form of evolution is how scientists erroneously define evolution, and also declare that this is actually what is seen in the fossil record.

This exposes how Creationists ignorantly perceive scientific theories as loose threads which they just have to pull on to unravel. Consistency isn't important, it's the undermining of an evolutionary account that matters.


Real crocoducks, y'all:-

Stuart, Y. E., et al. (2014). "Rapid evolution of a native species following invasion by a congener." Science 346(6208): 463-466.

In recent years, biologists have increasingly recognized that evolutionary change can occur rapidly when natural selection is strong; thus, real-time studies of evolution can be used to test classic evolutionary hypotheses directly. One such hypothesis is that negative interactions between closely related species can drive phenotypic divergence. Such divergence is thought to be ubiquitous, though well-documented cases are surprisingly rare. On small islands in Florida, we found that the lizard Anolis carolinensis moved to higher perches following invasion by Anolis sagrei and, in response, adaptively evolved larger toepads after only 20 generations. These results illustrate that interspecific interactions between closely related species can drive evolutionary change on observable time scales.

http://www.sciencemag.org/content/346/6208/463.abstract


The full paper is a free download from here.
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