I will be attending the Royal Society Meeting on New trends in evolutionary biology: biological, philosophical and social science perspectives. I'll post each of the abstracts and ask for your help in deciding what question to pose to the speakers. Here's the abstract for Gerd B. Müller's talk on The extended evolutionary synthesis.
Since the last major conceptual integration in evolutionary biology – the Modern Synthesis of the 1940s – the biosciences have made significant advances. The rise of molecular biology and evolutionary developmental biology, the recognition of ecological development, niche construction and of multiple inheritance systems, the -omics revolution and the science of systems biology, among other developments, have provided a wealth of new knowledge regarding the mechanisms of evolutionary change. Some of these results are in agreement with the classical Synthetic Theory and others reveal different properties of evolutionary change. A renewed and extended evolutionary synthesis unites pertinent concepts emerging from these novel fields with elements from the standard theory, but it differs from the latter in its core logic and predictive capacities. Whereas the classical theory had concentrated on genes and adaptive variation in populations, the extended framework emphasises the role of constructive processes, environmental induction, and systems dynamics in the evolution of organismal complexity. Single level and unilinear causation is replaced by multilevel and reciprocal causation. Among other consequences, this entails a revised understanding of the role of natural selection in the evolutionary process. The extended evolutionary synthesis complements the traditional gene centric perspective and stimulates research into new areas of evolutionary biology.There are so many things I could ask. I'm tempted to ask the following question,
Many of us believe that the role of adaptation in evolutionary theory was considerably revised by the development of Neutral Theory and Nearly-Neutral Theory almost 50 years ago. These concepts, and the importance of random genetic drift, have been integrated into the standard textbooks for many decades. Why don't you ever talk about those challenges to the old 1940s version of the Modern Synthesis? Is it because you don't think they were significant additions to the old theory?
10 comments :
1. To paraphrase Dan Graur et al. on the immortality of televisions, how can 80-90% of the genome in almost all eukaryotic lineages accumulate mutations at a rate consistent with neutral drift? If there is function in those regions, why is that function impervious to deleterious mutations? How can the bladderwort function with such a small genome?
2. Where does it state in the current Modern Synthesis that gene interactions have to be simple?
3. Phenotype plasticity can often result in deleterious phenotypes with respect to fitness, so why is phenotype plasticity so often described as being adaptive?
Well Eric, your world of estimated science does't work anymore in real, experimental world, starting with genetic load that you fell in love with so much, I assume.
These days, in real world, arguments mean shit. You either have experimental evidence or nobody will take your argument seriously... That's the new standard, if case you didn't know it.
Larry, the answer, which you may know already, is that these "extended synthesis" people don't care about molecular evolution. It isn't important for them. They care about visible features of animals, ideally large charismatic ones. Nothing you can tell them about molecular evolution would change their thinking.
This is the legacy of Mayr, et al., who absurdly claimed to have "unified biology" at the same time they were declaring that evolution might look different at the "molecular level" but it doesn't matter because the old views still apply to the stuff that matters, i.e., visible morphology.
The radical nature of molecular evolution is not just about neutrality. When results of molecular comparisons emerged in the 1950s and 1960s, a new view began to emerge, in which evolution was seen as a process in which mutations are proposed and then accepted or rejected. The Modern Synthesis view was that evolution is a process of shifting frequencies of pre-existing alleles at many loci, from the old multi-locus equilibrium, to a new one. In this view, the environment alone (via selection) determines the rate and direction of evolution, and the rate of evolution does not depend on the mutation rate.
Today this distinction has gone down the memory hole. Contemporary evolutionary geneticists (e.g., Orr, Weinreich, et al) refer to mutation-acceptance models of change as "Darwinian adaptation" without blinking an eye. They have no clue that for Mayr, Dobzhansky, Simpson, et al. disparaged this view of evolution as "pre-adaptation" and associated it with mutationists, not with their own neo-Darwinian view.
None of these people actually understand what the Modern Synthesis or neo-Darwinism originally represented as a scientific theory. Otherwise they would be saying it has been rejected rather than saying it must be "extended".
It's too bad you aren't speaking at this conference. Your ideas are much more important than anything else that will be presented on extending evolutionary theory.
I doubt that anyone at the conference, other than me, even knows about mutationism or mutation-drive evolution. I'm going to ask around to find out how many have read your papers or Nei's book. (Maybe Futuyma?)
First, I wasn't aware I fell in love with genetic load. If you are referring to the Genetic Entropy BS that creationists push, then be assured that I have no love for it.
Also, the experimental evidence is in. 80-90% of the human genome is accumulating mutations at a rate consistent with genetic drift. This is the experimental evidence for 80-90% of the human genome being disposable with respect to sequence specific function.
I agree fully with you, Arlin
"The Modern Synthesis view was that evolution is a process of shifting frequencies of pre-existing alleles at many loci, from the old multi-locus equilibrium, to a new one. In this view, the environment alone (via selection) determines the rate and direction of evolution, and the rate of evolution does not depend on the mutation rate. " You are mistaken because you use the term 'evolution' in various meanings without realising it. According to the MS, genetic evolution is indeed a process of shifting allele frequencies. However, these changes are not only determined by natural selection, but also by drift, mutations and gene flow. At the organismal level, by contrast, (adaptive) evolution is, indeed, solely determined by natural selection and the rate of that kind of evolution does not depend of the genetic mutation rate.
@koen
Arlin is well aware of the meaning of and various mechanisms contributing to evolution, and I debated him on occasion on this topic. I think he is correct in saying that there are many instances where mutation is the rate-limiting step of adaptive evolution, especially in microbial evolution. One need only look at Richard Lenski's long-term evolution experiment that gets frequently discussed here. Arlin wrote a series of very nice posts here explaining his views. Here is the last installment of the series, where you'll find the links to all the previous posts.
By the way, Larry is going to roast you for suggesting that organismal evolution is "solely determined by natural selection". ;-)
Hi Corneel, Thanks for the link. I'm afraid though, that he reads way too much in the idea that mutations are more important to (somatic) evolution than once thought (rate-limiting). Like all those other biologists-with-a-pet-idea (niche construction, phenotypic plasticity, epigenetic inheritance, horizontal gene transfer, gaps in the fossil record, etc., etc.). Any credible theory of evolution is still faced with the same, huge challenge Darwin was faced with in 1837: the origin of adaptations, the alpha and omega of life (the second major challenge is an explanation of speciation). We only have one credible answer: natural selection. And that will always remain the only credible answer. That's why the MS can't be (completely) wrong (as even Eldredge, 1985, p. 6 said). It can only be incomplete/imperfect. Ps: The word 'adaptive' should indeed not have been put between brackets.
One of the biggest challenges is deciding whether something actually IS an adaptation. If it is, then natural selection provides part of the explanation but in most cases mutation and drift play important roles (see drift-barrier hypothesis).
In some cases, e.g. constructive neutral evolution, natural selection may not even be important in the explanation.
In any case, the role of mutationism is not primarily to explain adaptations ... it's to explain the particular pathway that lineages followed over time. Natural selection alone can't explain the history of life.
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