Re: Remine & Haldane on sci.bio.evolution

I posted this first about 10 hours ago, but have not seen it, so
this is a second try.

jimmenegay@xxxxxxxxxxxxx wrote:
Friar Broccoli wrote:
David Wilson wrote:
In article <e7rkoj$2qgt$1@xxxxxxxxxxxxxxxxxxx> on June 27th in
sci.bio.evolution "Perplexed in Peoria" <jimmenegay@xxxxxxxxxxxx> wrote:

Felsenstein recently mentioned a 1968 paper by Sved. Quoting from
the introduction of that paper:

Haldane (1957) was apparently the first to approach concisely
the problem of estimating evolutionary rates and to put forward
the view that the intensity of selection observed for most species
implied that there must be an upper limit to the possible rate
of their evolution. In discussing this point, he introduced the
notion of "the cost of natural selection". Assuming selection
to occur through the death in each generation of a constant
proportion of individuals carrying a particular gene, he calculated
that the total number of "selective deaths" occurring in the
replacement of that gene is of the order of 30 times the population
size, independent of the strength of selection involved. From
this he concluded that there could not be much more than one
substitution per genome per 300 generations on the average, based
on the view that most species could not tolerate a depression in
fitness of more than 10% per generation due to this cause. A
similar figure was accepted by Kimura ...


I reread the following:

http://www.talkorigins.org/indexcc/CB/CB121.html


so I just want to make sure I understand.

Am I correct in believing that the reference to "sexual recombination"
just means that you can break the population into small groups (say
little tribes spread all over one or more continents) and apply
Haldane's limit to each group.


I'm not sure what that reference means, but I suspect it means
something different. In fact, I suspect it is wrong.

I interpret it as implying that since recombination can place
two good alleles or two bad alleles into a single individual,
you can get two units worth of evolution for the cost of one.
It also seems to suggest that Haldane and ReMine failed to
consider this possibility.

As I understand it, this is exactly the argument made in the
page (which you described as "pretty good") at:

http://www.gate.net/~rwms/haldane1.html

in the section:
"Multiple Simultaneous Substitutions Lower the Cost Even
Further"

The suggestion that they failed to consider it is ridiculous
and the implication, as I (mis?)understand it, is wrong.
Recombination also means that half of the population will have
one good and one bad gene. And that means that while one
selective death does two units of work, the other selective
death does nothing.

As I (mis?)understand it this argument fails because during
most of the fixation process far less than 1/2 the individuals
possess each beneficial mutation. Consequently a small number
of individuals enjoy a high selective advantage, while most
enjoy little or no advantage.

However the math (as always) confuses me.

Every analysis of the issue, including Haldane's and ReMine's,
has taken recombination into account. It is not the magic
bullet refuting Haldane.

I agree. From my hazy understanding, this seems to me to be a
very minor point.


Thus two separate groups could each evolve (and fix) a different
beneficial enhancement and then at a later time individuals from each
group could combine the characteristics.

Thus if there were 100 groups Haldane's limit could be multiplied by
100, from 1,667 to 166,700.

Do I have this right?

I'm pretty sure this doesn't work either. For one thing, the
Haldane limit doesn't even apply to small populations. In a
small population, there is a more severe limit on adaptive
substitution - a small population is probably limited by the
fact that it doesn't even get beneficial mutations all that
often.

OK, this kills my argument/analysis.

And even if you start with a huge population, such that each
of your 100 demes is large enough that it faces the Haldane
limit rather than the mutation limit, it still probably
doesn't work. It is still going to take a long time for the
eventual merged population to sort out which good genes to
keep and which to discard.

And this renders my argument/analysis meaningless.

Deme #23 may have come up with a better version of the XYZZY
gene than did deme #73, though both were better than what you
started with. All your barriers accomplish is to defer the
merge. My intuition tells me that you get better throughput
using a merge-as-you-go strategy. But then, my intuitions
have been wrong before.

You might have more confidence in your intuitions if you
thought they were the result of your being created in the image
of God. Those evolutionarily derived ones suck.


There is a link from the CB121 page to a web site by Williams
that is pretty good. And it references and describes research
by Ewens which suggests that a limit does exist, but it is
closer to something like 10 generations per substitution than
to the 300 generations estimated by Haldane.

I presume that comes mostly from the "soft selection" of
beneficial mutations argument (forms of which Jim Lovejoy and I
made during the last few days). Haldane assumed selection
under very severe conditions.

ReMine's argument is weak. Silly statements like
"Recombination solves the problem" don't make his argument
weaker. Instead they stregthen his secondary argument that
evolutionists are conducting a campaign of falsehood and
confusion.

Personally, I think the best argument (only because it is the
simplest) is that 1667 beneficial mutations is more than enough
to separate us from chimps, especially since only about 3% of
our DNA actually codes for functioning genes.

Thanks for encouraging me to do a little work on this issue.

Cordially;

Friar Broccoli
Robert Keith Elias, Quebec, Canada Email: EliasRK (of) gmail * com
Best programmer's & all purpose text editor: http://www.semware.com

--------- I consider ALL arguments in support of my views ---------

.

Relevant Pages