Re: Haldane's Dilemma and quantitative genetics


Perplexed in Peoria wrote:
"ErikW" <bryophyta@xxxxxxxxxxx> wrote in message news:e8up4a$grm$1@xxxxxxxxxxxxxxxxxxxxxx

ErikW wrote:
Perplexed in Peoria wrote:


But now we are in the genomic era, and there is some new evidence on
rates of selective substitution that may make the issue empirically
relevant again.

Since you're interested in this you should probably check out the data
on maize where the ancestral species teosinte still exist. I think you
could do a rough analysis with the numbers available today to see if it
falls within predicted ranges or not.

Here's an article on the effects of domestication/artificial selection
on 774 genes.
http://tinyurl.com/lnxrz - [thx, JAH]

From the article: "If we assume that our sample of genes is
representative, approximately 1200 genes throughout the maize genome
have been affected by artificial selection."

I'm reasonably sure that there is data for neutral substitutions,
population sizes, time to MRCA etc. to be had.

Thx, EricW, for the suggestion.

Well, just guessing that the MRCA was something like 5000 years ago,
and assuming that 1 yr = 1 generation, that works out to something like
4 generations per substitution. Not a problem for my notion of the size
of the limit, and possibly not even a problem for ReMine, since the
reproductive excess for cultivated teosinte or maize should be something
like 300 times the 0.1 that ReMine estimates as the reproductive excess
of humans.

In theory, artificial selection by a scientist who can do genome sequencing
might be able to 'beat' the limit, but I think that artificial selection
in the form of good old fashioned selective breeding should still be
subject to a Haldane limit, if one exists.

I had some second thoughts. Selection on 1200 loci doesn't mean 1200
substitutions. I suspect this is trickier than I first anticipated.
I'll do some rereading.


.

Relevant Pages

  • Re: The Cost of Substitution [possible REPOST]
    ... cost of substitution and Haldane's Dilemma. ... Wilson basically supports ReMine on the 'misrepresentation' question, ... The criticisms which CB121 makes of Haldane's "Cost of Natural Selection" are ...
    (sci.bio.evolution)
  • Re: Reproductive Excess: Is Required
    ... >> evolution due to selection is slow - does seem ... Haldane assumed slowness FOR EACH ALLELE so as ... > to obtain the absolute lowest total cost of substitution PER ALLELE. ...
    (sci.bio.evolution)
  • Re: Reproductive Excess: Is Required
    ... >>> Try a thought experiment where the selection is ... >> Your scenario is a classic type of cost-confusion. ... >> speeded up the substitution from 300 generations to 1 ... an unrealistically high rate of beneficial mutation. ...
    (sci.bio.evolution)
  • Re: Reproductive excess model
    ... > So clearly the maximum fixation rate is one allele per generation. ... > beneficial substitution can be no faster than 1 per 300 generations ... divided by a reproductive excess of 0.1 is: ... modeling survival selection, and ignores fecundity selection. ...
    (sci.bio.evolution)
  • Re: Reproductive Excess: Is Required
    ... Haldane used small selection coefficients ( ... Haldane assumed slowness FOR EACH ALLELE so as ... to obtain the absolute lowest total cost of substitution PER ALLELE. ...
    (sci.bio.evolution)