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  1. Last 7 days
    1. Motoo Kimura, author of the book, The Neutral Theory of Molecular Evolution, published in 1983, more than a hundred years after Darwin's masterpiece.

      !- Title : The Neutral Theory of Molecular Evolution, published in 1983 !- Author : Motoo Kimura

    2. After the discovery of the structure of DNA molecules by Crick and Watson in 1953, Kimura knew that genes are molecules, carrying genetic information in a simple code. His theory applied only to evolution driven by the statistical inheritance of molecules. He called it the Neutral Theory because it introduced Genetic Drift as a driving force of evolution independent of natural selection.

      !- reason behind name of theory : independent of natural selection

    3. Sewall Wright, then 98 years old but still in full possession of his wits. He gave me a first-hand account of how he read Mendel's paper and decided to devote his life to understanding the consequences of Mendel's ideas. Wright understood that the inheritance of genes would cause a fundamental randomness in all evolutionary processes. The phenomenon of randomness in evolution was called Genetic Drift. Kimura came to Wisconsin to learn about Genetic Drift, and then returned to Japan. He built Genetic Drift into a mathematical theory which he called the Neutral Theory of Molecular Evolution.

      !- Sewall Wright : genetic drift

  2. Jul 2020
  3. Feb 2019
    1. n they will share similar genes, but it 18is the phenotype –upon which selection acts –which is crucia

      There two important things to note.

      1. If the same genetic programme leads to two phenotypes because of the environment, this falls in the category of epigenetics. Epigenetic processes are usually not tree-like, hence, poorly modelled by inferring a tree.

      2. You implicitly assume (via your R-script) that homoiologies (in a strict sense, i.e. parallelism) are rare and not beneficial (neutral). But if the homoiology is beneficial (i.e. positively selected for), it will be much more common in a clade of close relatives than the primitive phenotype (the symplesiomorphy). We can further assume that beneficial homoiologies will accumulate in the most-derived, advanced, specialised taxa, in the worst case (from the mainstream cladistic viewpoint) mimicking or even outcompeting synapomorphies. A simply thought example: let's say we have a monophylum (fide Hennig) with two sublineages, each sublineage defined by a single synapormorphy. Both sublineages radiate and invade in parallel a new niche (geographically separated from each other) and fix (evolve) a set of homoiologies in adaptation to that new niche. The members of both sublineages with the homoiologies will be resolved as one clade, a pseudo-monophylum, supported by the homoiologies as pseudo-synapomorphies. And the actual synapomorphies will be resolved as plesiomorphies or autapomorphies.

      Without molecular (and sometime even with, many molecular trees are based on plastid in plants and mitochondria in animals, and both are maternally inherited, hence, geographically controlled) or ontological-physiological control it will be impossible to make a call what is derived (hence a potential homoiology) and what ancestral in a group of organisms sharing a relative recent common origin and a still similiar genetic programme.