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Friday, September 30, 2016

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.


  1. Larry, I feel your future pain. As for that abstract, I have no idea what the guy means.

    1. I feel your pain now though not to mention the future one Jerry. Sticking to your only gun-natural selection as the main mechanism of evolution isn't going to get you much support now and in the future, even from Larry.

      Since you have retired from your so-called scientific work, I think the time has also come to retire the 150 year old myth of natural selection as being the driving force behind evolution, don't you think Jerry?

    2. I like "so-called" the best. Anyone else?

  2. Development is an outcome of heredity. This has already been well established.

    If I were in a smart ass mood I might ask Dr. Uller what environmental conditions would cause a human to give birth to a cat.

  3. @Larry, are you implying that heritable epigenetic changes aren't "heredity"? As far as I can see, they are, though the inheritance is very imperfect.

    And "plasticity" describes the way a given genotype responds to environments in causing a phenotype. The plastic response itself is not inherited. It puzzles me why "plasticity and epigenetics" are alternatives to "heredity". The former is not inherited, except in that genotypes that are differently plastic get inherited. The latter is a kind of heredity.

    1. Welcome to the world of epigenetics Joe!

      I had thought you'd never make it. Well, I guess I'm getting old or naive...

      I hear that Harshman and Mitzke are making a come back too but Nick reluctantly though...

      Can you explain a bit further what "kind of heredity means please?

    2. @Larry, are you implying that heritable epigenetic changes aren't "heredity"? As far as I can see, they are, though the inheritance is very imperfect.

      It depends on how you define "heridity." In the case of methylation let's review what we know about restriction/modification in bacteria. When the cell divides, the daughter cells each receive a single strand of DNA from the parent and that DNA will be methylated. The newly replicated strand will not be methylated so the site won't protect against restriction endonucleases. However, the methylase enzyme in the daughter cell will recognize the hemimethylated site and add a methyl group to the other stand. Thus the site will become protected.

      I'm happy to count this as heritable but I don't think we need to revise evolutionary theory because of it. Restriction/modification was worked out in the 1970s and I don't recall any clamor for changes in evolutionary theory.

      The situation with respect to modified histones is much more complicated. There are no histones on sperm DNA so the zygote can't inherit such modifications from males. The modified histones may be passed from the female to the zygote if they survive meiosis and if the female germ cell had the appropriate markers in the first place.