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Natural selection has limits? Who knew?

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From Trends in Genetics:

Evolutionary theory predicts that factors such as a small population size or low recombination rate can limit the action of natural selection. The emerging field of comparative population genomics offers an opportunity to evaluate these hypotheses. However, classical theoretical predictions assume that populations are at demographic equilibrium. This assumption is likely to be violated in the very populations researchers use to evaluate selection’s limits: populations that have experienced a recent shift in population size and/or effective recombination rates. Here we highlight theory and data analyses concerning limitations on the action of natural selection in nonequilibrial populations and argue that substantial care is needed to appropriately test whether species and populations show meaningful differences in selection efficacy. A move toward model-based inferences that explicitly incorporate nonequilibrium dynamics provides a promising approach to more accurately contrast selection efficacy across populations and interpret its significance.
More.

Abstract for The Limits of Natural Selection in a Nonequilibrium World by Yaniv Brandvain, Stephen I. Wright (paywall)

See also: Natural selection: Could it be the single greatest idea ever invented? (Yes, if you want to throw a shoehorn into the works of understanding evolution.)

and

Talk to the fossils: Let’s see what they say back

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7 Replies to “Natural selection has limits? Who knew?

  1. 1
    Larry Moran says:

    Dear Denyse,

    I’ve been telling you about the limits of natural selection for over 15 years. The basic principles of population genetics explain the competition between natural selection and random genetic drift and how it is affected by population size. The central idea was developed in the early 1970s by Tomoko Ohta (see Nearly-Neutral Theory).

    It’s very frustrating to have to explain this to you over and over and over again. You don’t have to believe it but please stop pretending that it’s new and revolutionary every time you come across someone who mentions it.

  2. 2
    Mung says:

    Hi Larry,

    Over at another blog I stated that in small populations genetic drift ought to overcome the effects of selection.

    I was told that this is false and that I was wrong and that I had quote-mined my source and didn’t understand what they were really saying.

    The quote and the source:

    In other words, in small populations, the stochastic effects of random genetic drift overcome the effects of selection.

    Neutral Theory: The Null Hypothesis of Molecular Evolution

    Who knew.

    Genetic Algorithms: When Drift Overcomes Selection

    A selection-vs-drift version of Weasel

  3. 3
    wd400 says:

    Over at another blog I stated that in small populations genetic drift ought to overcome the effects of selection.

    At realistic selection coefficients that’s a pretty good approximation. The more useful way to think about this is to say drift dominates when Ns (population size x the selection coefficient) is < 1. In the weasel all non-optimal strings die so "s" is…basically infinite. Selection will dominate.

  4. 4
    mahuna says:

    So, as with the Climate Change fanatics, the Evolution fanatics are trying to tell us that a computer model is BETTER than any actual field data?

    I think that surrendering to the Model Makers would be the end of Science, since the Model Makers live to produce modeling results that feed proposals for new grants.

    But that’s what “science” is all about, right? It’s about the right people getting lots of grant money instead of working for a living.

  5. 5
    Virgil Cain says:

    Moran:

    I’ve been telling you about the limits of natural selection for over 15 years.

    Natural selection is still the only stochastic process that allegedly has creative powers, even though that has never panned out. That is what we have been telling Larry for decades and he still can’t get that simple fact through his thick skull.

  6. 6
    J-Mac says:

    Unfortunately, despite the scientific evidence indicating the limitations as to what natural selection to accomplish in the evolutionary processes, Darwinists like Coyne and Dawkins will continue to ignore it and write more shitty books.

  7. 7
    Bob O'H says:

    mahuna – no, they’re saying that the combination is better. That’s the inference in “model-based inference”.

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