linkstream2 microblog

QT:{{”
The author goes further in discussing the evolutionary processes. He considers the view of the modern synthesis, which focuses on variation and selection, too simplistic. Hence he proposes to adopt a multifactorial view, and to recognize three modalities of evolution, so-called Darwinian (random mutation and selection), Lamarckian (directed mutation) and Wrightian (random mutation and random fixation), the latter from Sewall Wright, one of the founders of population genetics. As an example of Lamarckian modality, Koonin mentions the CRISPR system in bacteria, where ‘acquired’ modifications are transmitted in the genome (Koonin & Wolf, 2009).

Now here, if I’m not mistaken, we enter territories devoid of consensus among evolutionary biologists. (I’m not an evolutionary biologist, and I admit that the subtleties of the debate often escape me.) For instance Patrick Forterre, from the Institut Pasteur, is very critical of what he calls “the false come back of Lamarck” (Forterre, 2012). He considers the CRISPR example as misleading, and that in essence this is a Darwinian phenomenon.
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http://ofbacteriaandmen.blogspot.com/2012/09/the-logic-of-chance-by-eugene-koonin_22.html

QT:{{”
Various forms of stress-induced mutagenesis are tightly regulated and comprise a universal adaptive response to environmental stress in cellular life forms. Stress-induced mutagenesis can be construed as a quasi-Lamarckian phenomenon because the induced genomic changes, although random, are triggered by environmental factors and are beneficial to the organism.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2781790/

QT:{{”
Moreover, the children of the women who were pregnant during the famine were smaller, as expected. However, surprisingly, when these children grew up and had children those children were thought to also be smaller than average.[8] These data suggested that the famine experienced by the mothers caused some kind of epigenetic changes that were passed down to the next generation. Despite this, a subsequent study by the same author failed to find a correlation between maternal exposure to famine and birth weight of the next generation.[9] “}}

https://en.wikipedia.org/wiki/Dutch_famine_of_1944

– quite a revolutionary perspective on evol. in its day
– a bit of resurgence in interest now w/ epigenetics

https://en.wikipedia.org/wiki/Jean-Baptiste_Lamarck

https://en.wikipedia.org/wiki/Canalisation_(genetics)

Tagged w/ “gettysburg tryptophan deeper”
or
http://linkstream2.gerstein.info/tag/deeper0mg

http://www.amazon.com/The-Deeper-Genome-there-genome/dp/0199688737