Re: Article: Beyond a 'speed limit' on mutations, species risk extinction
- From: Tim Tyler <seemysig@xxxxxxxxxxxxxx>
- Date: Fri, 5 Oct 2007 13:28:32 -0400 (EDT)
inmanh@xxxxxxxxxxxxxx wrote:
On Oct 3, 6:25 pm, Tim Tyler <seemy...@xxxxxxxxxxxxxx> wrote:
Robert Karl Stonjek wrote:
Beyond a 'speed limit' on mutations, species risk extinction
Harvard University scientists have identified a virtual "speed limit" on the
rate of molecular evolution in organisms, and the magic number appears to be
6 mutations per genome per generation -- a level beyond which species run
the strong risk of extinction as their genomes lose stability.
From adult to adult presumably - and ignoring junk DNA.
This is rather contrary to population genetics:
``If the offspring have on the average one harmful mutation each,
then the population will degenerate; this is called "error
catastrophe." This puts a bound on how many non-neutral mutations
can occur per generation. It cannot be much more than about one
per generation, and in fact, it must be significantly less, since
most non-neutral mutations are harmful.''
-http://www.cs.unc.edu/~plaisted/ce/genetics.html
(A) This latter statement must in general be false, because any such
error catastrophe depends in part on the typical number of offspring
an individual has. If species X has an average 32 offspring per
individual (of which one typically survives to maintain constant
population size) whereas species Y, otherwise similar, has only 2
offspring (of which one survives), then X can have 6 times the
mutation rate of Y before reaching any such error catastrophe. Hence
any such general statement must include some factor log(avge num
offspring) in there -- and log2(32)=6.
As with the original article, I think this can be reasonably
expected to be adult-to-adult (or similar) - otherwise oysters
and elms would be a /serious/ spanner in the works.
This whole topic - including the reference to a speed limit - does
relate to a paper previously discussed on occasion here:
R.P. Worden. A Speed Limit For Evolution
Journal of Theoretical Biology, 176, 137 - 152, 1995
available on
http://dspace.dial.pipex3.com/jcollie/sle/
I was never very impressed with that one:
``Worden's whole paper seems to be almost entirely without merit.''
- http://alife.co.uk/essays/no_speed_limit_for_evolution/
Notes:
Correct URL: http://dspace.dial.pipex.com/jcollie/sle/
Anal nit-pick: log2(32)=5! ;-)
--
__________
|im |yler http://timtyler.org/ tim@xxxxxxxxxxx Remove lock to reply.
.
- References:
- Article: Beyond a 'speed limit' on mutations, species risk extinction
- From: Robert Karl Stonjek
- Re: Article: Beyond a 'speed limit' on mutations, species risk extinction
- From: inmanh
- Article: Beyond a 'speed limit' on mutations, species risk extinction
- Prev by Date: Re: Evolution increases the computational ability of organisms.
- Next by Date: Re: Evolution increases the computational ability of organisms.
- Previous by thread: Re: Article: Beyond a 'speed limit' on mutations, species risk extinction
- Next by thread: Re: Article: Beyond a 'speed limit' on mutations, species risk extinction
- Index(es):
Relevant Pages
|
