Regarding Kondrashov’s paper Why have we not died 100 times over?, an internet “pupil” of mine who goes by the handle of “nomenmeum” asked what is synergistic epistasis and soft selection. The definition of synergistic epistasis seems to be the major issue as I don’t see the term much in literature. I don’t know exactly what it means. Does synergistic epistasis entail a change in S-coefficients?
For example in Brenda Andrews’ double and triple knockout experiments with yeast, the corresponding single knockout experiments had little-to-no noticeable effects, but several double and triple knockouts would clearly have deleterious effect when their component individual single knockouts did not in isolation.
Below is Brenda Andrews’ description of her experiment which I mentioned at Sandwalk in connection with the ENCODE 2015 planning meeting (Larry Moran knew Dr. Andrews as a graduate student at his school):
So I would presume a double knockout scenario that was deleterious where the component individual knockout scenarios were neutral, the S-coefficients would change between the different scenarios. Is this an example of synergistic epistasis?
“This paradox [i.e., humans existing for millions of years and yet not dying out 100 times over as a result of error catastrophe] cannot be resolved by invoking beneficial mutations or environmental fluctuations. Several possible resolutions are considered, including soft selection and synergistic epistasis among very slightly deleterious mutations.”
Thanks in advance for any responses.
There were two major ENCODE 2015 meetings, one for users, one for planners. I was in the users meeting, not in the planning meeting. Brenda Andrews presented at the planning meeting. Larry Moran knew Brenda Andrews and her work was discussed in passing here:
What did ENCODE Researchers Say on Reddit