Extending evolutionary theory? - Eva Jablonka

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 Eva Jablonka's talk on
The role of epigenetic inheritance in evolution.

The construction of the ‘Modern Evolutionary Synthesis’ in the mid-twentieth century involved the exclusion of soft inheritance – the inheritance of the effects of developmental modifications – and, by implication, the possibility of any form of ‘Lamarckian’ evolution. However, in later decades, discoveries of molecular mechanisms that can support such inheritance led to a broadening of the notion of biological heredity. After discussing the historical context in which this change occurred, I present an extended notion of inheritance, focusing on epigenetic inheritance and its underlying mechanisms. I examine the evidence for the ubiquity of epigenetic inheritance, present models of population epigenetics, and discuss the involvement of epigenetic inheritance in adaptive evolutionary change and macro-evolution. I argue that considering the many evolutionary consequences of epigenetic inheritance requires an extension of the evolutionary synthesis beyond the current neo-Darwinian model.

Eva Jablonka has been pushing the importance of epigenetics for many years. Here's a video where she explains why epigenetic inheritance needs to be incorporated into evolutionary theory.


I think she's exaggerating the importance of epigenetic inheritance in evolution. I'd like to ask her how she defines "epigenetics" and how much of it is heritable over enough generations to seriously affect the evolution of a population. I'm particularly interested in her claim that epigenetic inheritance affects macro-evolution.

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Extending evolutionary theory? - Paul E. Griffiths

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 Paul Griffiths's talk on Genetic, epigenetic and exogenetic information in development and evolution.

I outline an approach to measuring biological information where ‘information’ is understood in the sense found in Francis Crick’s foundational contributions to molecular biology. Genes contain information in this sense, but so do epigenetic factors, as many biologists have recognised. The term ‘epigenetic’ is ambiguous, and I introduce a distinction between epigenetic and exogenetic inheritance to clarify one aspect of this ambiguity. These three heredity systems play complementary roles in development and evolution.

Paul Griffiths is a philosopher of biology from Australia. He has been interested in genes for many years. I don't know what he's going to say about epigenetics. I suspect he can make a case for information in the sense that a naked DNA sequence differs in information from a methylated DNA sequence. (Restriction/modification is a good example.)

The problem with this kind of hair splitting is that ultimately the extra information (e.g. methylation) is provided by enzymes (methylases) encoded by genes in the genome. Epigenetics, per se, doesn't add any new information. It's just a consequence, or outcome, of the information already in the DNA.

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Extending evolutionary theory? - James Shapiro

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 James Shapiro's talk on Biological action in Read-Write genome evolution.

Many of the most important evolutionary variations that generated phenotypic adaptations and originated novel taxa resulted from complex cellular activities affecting genome content and expression. These activities included: (i) the symbiogenetic cell merger that produced the mitochondrion-bearing ancestor of all extant eukaryotes; (ii) symbiogenetic cell mergers that produced chloroplast-bearing ancestors of photosynthetic eukaryotes; and (iii) interspecific hybridisations and genome doublings that have generated adaptive radiations and new species of higher plants and animals. Adaptive variations have also arisen by horizontal DNA transfers (frequently involving infectious agents), by natural genetic engineering of coding sequence DNA in protein evolution (e.g. exon shuffling), and by mobile DNA rewiring of transcriptional regulatory networks, such as those essential to viviparous reproduction in mammals. In the most highly evolved multicellular organisms, we now know that biological complexity scales with ‘non-coding’ DNA content rather than with protein-coding capacity in the genome. Coincidentally, we have come to recognise that ‘non-coding’ RNAs rich in repetitive mobile DNA sequences function as key regulators of complex adaptive phenotypes, such as stem cell pluripotency. The intersections of cell activities and Read-Write genome modifications provide a rich molecular and biological foundation for understanding how ecological disruptions can stimulate productive, often abrupt, evolutionary transformations.

I have dozens of questions for Jim Shapiro but here are two possibilities.

Most of the events you describe are one-off events in the history of life. They are mostly accidents. They were unpredictable. How does the occurrence of unique events such as endosymbiosis or genome doubling fit into evolutionary theory as opposed to just historical facts in the history of life.

OR

Michael Lynch and others say that the amount of junk DNA in a genome correlates with the population size of the species. This view is perfectly consistent with modern population genetics. There is plenty of evidence that 90% of our genome is junk. You seem to be implying that this extra DNA is not junk but serves some adaptive purpose. What evidence do you have that supports this claim and why do you disagree with Michael Lynch?

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Extending evolutionary theory? - Kevin Laland

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 Kevin Laland's talk on The middle ground between artificial and natural selection: niche construction as developmental bias.

Organisms modify and choose components of their local environments. This ‘niche construction’ is subject to extensive research across several academic fields. It is well appreciated that niche construction can alter ecological processes, modify natural selection, and contribute to inheritance through ecological legacies. However, niche construction is not usually regarded as an evolutionary process, probably because traditional evolutionary accounts restrict evolutionary processes to phenomena that directly change gene frequencies (e.g. selection, mutation, drift).

Alternative perspectives can be of value if they generate novel predictions, open up new lines of enquiry, or generate new insights. The niche-construction perspective within evolutionary biology provides an alternative account of the causal relations underlying adaptation, a stance that has already led to a number of valuable insights. Here I suggest that there is heuristic value in regarding niche construction as an evolutionary process, on the grounds that it initiates and modifies the selection acting back on the constructor (and other species) in an orderly and directional manner. As a consequence, niche construction co-directs adaptive evolution by imposing a statistical bias on selection (an externally expressed form of developmental bias).

I illustrate how niche construction can generate developmental bias by comparing it with artificial selection, where I suggest it occupies the middle ground between artificial and natural selection. This perspective has heuristic value for the evolutionary biologist, leading to testable predictions related to: (i) trait evolution, including the evolution of sequences of traits and parallel evolution; (ii) responses to natural selection in the wild; and (iii) biodiversity.

I don't get this emphasis on niche construction. Biologists have been talking about how organisms modify the environment for one hundred years or more. I can see how an understanding of particular examples, such as the increase in oxygen levels due to the evolution of water splitting reactions, can provide insight into the history of life but how does that fit into evolutionary theory?

I don't have any questions for Kevin Laland. I'm anxious to see how the people at this meeting view niche construction.

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Extending evolutionary theory? - Paul Brakefield

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 Paul Brakefield's talk on Does the way in which development works bias the paths taken by evolution?

Developmental bias was defined in a seminal review some thirty years ago that resulted from an early ‘meeting of minds’ of developmental and evolutionary biologists driven by John Maynard Smith and Lewis Wolpert. Although there has been dramatic progress since then in revealing in exquisite detail how morphologies develop, there are few well-worked case studies of potential developmental bias, as well as little understanding of how important the process has been in shaping the evolution of animal form. Therefore, it is timely to think about what is needed to facilitate the analysis of the extent to which patterns of evolutionary diversification are biased by how development works, and indeed whether it is useful to distinguish this process from that of genetic channeling.

Here are two possible questions for Paul Brakefield ...

Stephen Jay Gould published Ontology and Phylogeny in 1977. He wrote extensively about developmental constraints until his death in 2002. Richard Dawkins also wrote about developmental constraints, most notably in his discussion of whether pigs could fly in The Blind Watchmaker. How do your views differ from those that have been around for decades and why do you think it requires a modification of evolutionary theory today?

OR

In The Structure of Evolutionary Theory, Gould wrote 270 pages on developmental constraints emphasizing their POSITIVE role in evolution as opposed to just their negative effects on limiting natural selection. He said,

The concept of constraint must include theoretically legitimate and factually important positive meanings—i.e., constraints as directing causes of particular evolutionary changes—rather than only the negative connotations of structural limitations that prevent natural selection from crafting an alteration that would otherwise be favored and achieved.

How do your views differ from what Gould wrote about so extensively in 2001?

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Extending evolutionary theory? John Dupré

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 John Dupré's talk on The ontology of evolutionary process.

Ontology is the branch of philosophy that considers in the most general way the nature of reality. An ancient and fundamental ontological question is whether reality is ultimately composed of stable things or is everywhere processual, in flux. A number of distinguished 20th century biologists, including, for instance Conrad Waddington, Joseph Needham, and Ludwig von Bertalanffy, thought it important to stress the fundamentally dynamic, processual character of living systems. While evolution is of course a process, it is often implicitly supposed that the entities that evolve or that constitute the evolutionary process, whether genes, organisms, populations, or whatever, are kinds of things. Following the authors mentioned above, I argue that these too are better seen as processes, albeit highly stabilised processes.

In this talk I shall argue that a process ontology is correct and that it has important implications for how we should think about evolution. First, with regard to the constituents of the evolutionary process, process ontology highlights the limitations of atemporal descriptions of organisms, for example in terms of gene sequence, and of populations as atemporal abstractions from evolving lineages. Second, whereas in an ontology of things the primary explanatory task is that of understanding change, in a world of process it is of equal or even greater importance to explain stability. The first step in articulating a fully processual view of evolution is to describe the processes that sustain persisting lineages. Doing so should provide fresh perspectives on the processes that can produce changes in lineages.

John Dupré is a philosopher. He talks like a philosopher. I don't understand what he's talking about and, quite frankly, I don't care. No questions for him.

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Extending evolutionary theory? - Tobias Uller

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 Tobias Uller's talk on Heredity and evolutionary theory.

Heredity is a central concept in biology and one of the core principles needed for evolution by natural selection. For most of the past century inheritance has been conceptualised and defined in terms of transmission of genes. Emerging developmental perspectives on evolution appear to challenge this perspective in several ways. Here I will explain how evolutionary biologists treat heredity conceptually and mathematically. These perspectives are heuristically useful but they impose a certain structure on evolutionary theory and leave out aspects of heredity that may be important to understand evolution. An alternative representation understands heredity as an outcome of developmental processes. I will suggest that this perspective helps to clarify how different mechanisms of inheritance contributes to evolution.

I have to wait to hear this talk in order to figure out what he means. From reading the abstracts to some of his papers I think he's going to promote plasticity and epigenetics ... or maybe maternal effects.

In any case, the standard understanding of "heredity" is when alleles (genes) are passed from one generation to another. The process usually involves DNA replication and cell division but it encompasses horizontal transmission. I'll be interested in hearing about other mechanisms of heredity.

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Extending evolutionary theory? - Russell Lande

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 Russell Lande's talk on Evolution of phenotypic plasticity.

The scope and relative rates of adaptive phenotypic change from plasticity versus standard Darwinian evolution adaptive genetic changes depend on the time scale and the range of phenotypic alteration being considered. This distinction becomes blurred when plasticity itself evolves. Using standard methods from neo-Darwinian population genetic theory, I review recent models on the evolution of phenotypic plasticity in changing environments, emphasising the roles of environmental predictability and costs of plasticity in constant and labile characters. Adaptation to a novel environment may often occur by rapid evolution of increased plasticity followed by slow genetic assimilation of the new phenotype. I elucidate the connection between environmental tolerance and plasticity. The theory of evolution of phenotypic plasticity is an important extension to neo-Darwinism, but does not necessitate a major revision of its foundations. The same conclusion applies to epigenetic mechanisms including interactions between genes or tissues in development, and to transgenerational phenotypic effects such as somatic inheritance, maternal effects and DNA methylation.

I could ask this question ...

Imagine a small group of organisms that find themselves in a new environment. Let's assume they have a genome containing 10,000 genes. How do they select for increased phenotypic plasticity in order to better adapt to the new environment? Are all genes affected or just a small number that might increase fitness? Which genes acquire additional potentially beneficial alleles that were not present in the small population before it encountered the new environment and how does that mechanism work?

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Extending evolutionary theory? - Sonia Sultan

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 Sonia Sultan's talk on Developmental plasticity: re-conceiving the genotype.

For several decades, the phenotype of an organism (i.e, its traits and behaviour) has been studied as the outcome of developmental ‘instructions’ coded in its DNA. According to this model, each genotype is expressed as a specific phenotype; individual differences in fitness-related traits are seen to arise from this stably inherited internal information. This simplified view of development provides the foundation for a Modern Synthesis approach to adaptive evolution as a sorting process among genetic variants. As developmental biologists are aware, however, an organism’s phenotype is not strictly pre-determined by its genotype, but rather takes shape through the interplay of genetic factors with the organism’s environmental conditions. By means of this developmental plasticity, a given genotype may express different phenotypes under different environmental conditions. Accordingly, the genotype can be understood as a repertoire of potential developmental outcomes or norm of reaction.

Re-conceiving the genotype as an environmental response repertoire rather than a fixed developmental programme leads to three critical insights, as illustrated by norm of reaction data from Polygonum plants. Plastic responses to specific conditions often comprise functionally appropriate trait adjustments, resulting in an individual-level, developmental mode of adaptive variation. Environmental responses can extend across generations via effects on progeny growth and fitness, a form of inherited yet non-genetic adaptation. Finally, because genotypes are differently expressed depending on the environment, the genetic diversity available to natural selection is itself environmentally contingent.

Here's a possible question ...

Back in the 1960s we learned that transcription of the lac operon in E. coli was regulated by the environment. This regulation, activation or repression, was passed on to daughter cells as the cells divided. Why didn't this discovery lead to a major revision of evolutionary theory?

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Extending evolutionary theory? - Douglas Futuyma

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 Douglas Futuyma's talk on The evolutionary synthesis today: extend or amend?

Evolutionary theory has been extended almost continually since the Evolutionary Synthesis, but the principal tenets of the Synthesis have been strongly supported, the single most important exception being the greater importance accorded genetic drift, especially in molecular evolution. The calls for an extended synthesis today are largely a continuation of this process. Some elements of the EES movement, such as the role of niche construction, are welcome emphases on long recognised but perhaps under-studied processes. The union of population genetic theory with mechanistic understanding of molecular and developmental processes is a potentially productive conjunction of ultimate and proximal causation; but the latter does not replace or invalidate the former. Newly discovered molecular genetic phenomena have been easily accommodated by orthodox evolutionary theory in the past, and this appears to hold also for phenomena such as epigenetic inheritance today. In several of these areas, empirical evidence is needed to evaluate enthusiastic speculation. Evolutionary theory today will continue to be extended, but there is no sign that it requires emendation.

Here are two possible questions for Futuyma.

Why do you think that most participants at this meeting seem to be unaware of random genetic drift and the evolution of structures and phenotypes by nonadaptive processes? Doesn't this strike you as bizarre for a group that's so concerned about evolutionary theory?

As you explain in your textbook, describing the pathways to modern species contributes to the FACT of evolution and the FACT of descent with modification but how those genetic changes actually occur and become fixed is part of evolutionary theory. Do you distinguish between evolutionary theory and the actual history of life?

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Extending evolutionary theory? - Gerd B. Müller

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?

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A philosopher's view of random genetic drift

Random genetic drift is a process that alters allele frequencies within a population. The change is due to "random" events. It differs from natural selection where the change is due to selection for alleles that confer selective advantage on the reproductive success of an individual. Here's one description,

If a population is finite in size (as all populations are) and if a given pair of parents have only a small number of offspring, then even in the absence of all selective forces, the frequency of a gene will not be exactly reproduced in the next generation because of sampling error. If in a population of 1000 individuals the frequency of "a" is 0.5 in one generation, then it may by chance be 0.493 or 0.505 in the next generation because of the chance production of a few more or less progeny of each genotype. In the second generation, there is another sampling error based on the new gene frequency, so the frequency of "a" may go from 0.505 to 0.501 or back to 0.498. This process of random fluctuation continues generation after generation, with no force pushing the frequency back to its initial state because the population has no "genetic memory" of its state many generations ago. Each generation is an independent event. The final result of this random change in allele frequency is that the population eventually drifts to p=1 or p=0. After this point, no further change is possible; the population has become homozygous. A different population, isolated from the first, also undergoes this random genetic drift, but it may become homozygous for allele "A", whereas the first population has become homozygous for allele "a". As time goes on, isolated populations diverge from each other, each losing heterozygosity. The variation originally present within populations now appears as variation between populations.

Suzuki, D.T., Griffiths, A.J.F., Miller, J.H. and Lewontin, R.C.
in An Introduction to Genetic Analysis 4th ed. W.H. Freeman (1989 p.704)

A theology student doesn't like Jerry Coyne's book Faith vs. Fact

A theology student named Derrick has written a review of Jerry Coyne's book Faith vs. Fact. He didn't like it very much. (Duh!) You can read his review at: Jerry Coyne, Faith Vs. Fact: Why Science and Religion Are Incompatible.

Before reading that review, let's make sure we understand Jerry's position. Here's what he says on page xx of his book.

My main thesis is narrower and, I think, more defensible: understanding reality, in the sense of being able to use what we know to predict what we don't, is best achieved using the tools of science, and is never achieved using the methods of faith. That is attested by the acknowledged success of science in telling us everything from the smallest bits of matter to the origin of the universe itself—compared with the abject failure of religion to tell us anything about gods, including whether they exist.

Can we ever know if god exists?

A recent issue of New Scientist (Sept. 3-9) is billed as "The Metaphysics Issue: How science answers philosophy's deepest questions." This is probably not going to make philosophers happy.

Several of the articles are devoted to the "big questions." According to New Scientist these questions are normally left to philosophers but the editors go on to say, "Now, though, scientists are increasingly claiming them as their own ..." Let's look at one of the questions: Can we ever know if God exists?. Here's the part I want to discuss ...

No one has proved that God exists, but then no one has proved there is no God. Is working out the truth a supernatural feat?

... Gallons of ink and blood have been spilled over this question but have largely got us nowhere. Belief in a god or several gods is a leap of faith. So is disbelief. The only coherent and rational position is agnosticism.

Really? Disbelief in Thor, Zeus, Quetzalcoatl, and Gitchi Manitou is a "leap of faith"? I have not been convinced by any evidence that these gods exist. Is that irrational and incoherent?

Ten adaptationist stories about recent human evolution

Does this video contribute to the general understanding and appreciation of science?

1. Blond hair: PROBABLY FALSE ADAPTATION
2. Lactose tolerance: PROBABLY A TRUE ADAPTATION
3. Eating wheat: PROBABLY FALSE ADAPTATION
4. Losing wisdom teeth: PROBABLY FALSE ADAPTATION
5. Smaller brains: LIKELY FALSE ADAPATION
6. Getting shorter: ALMOST CERTAINLY FALSE
7. Malaria resistance: CERTAINLY TRUE
8. HIV Resistance: TRUE BUT TRIVIAL
9. Male extroverts: PROBABLY FALSE ADAPTATION
10. Having kids earlier: ALMOST CERTAINLY FALSE ADAPTATION

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