[email hidden] wrote in message news:<[email hidden]>...
Quoted message said:[moderator's note: I don't really understand this, but I
know Mats, and he's not at all about creationism or
anything, so here goes. Anyone want to comment? - JAH]
I'm sure there are people better qualified to comment than
I, but I'll give it a try. Mats' theory seems to be about
sympatric speciation, but it also seems to cover speciation
events so "revolutionary" that the parent species dies in
childbirth. (Is this "speciation"?) Maybe the title of the
post is appropriate, but as Josh notes, the word "creation"
is unfortunate from the standpoint of American readers.
I'm guessing that this is very similar to a theory that Mats
explained in a series of posts back in 1996-1997. If so,
interested parties may wish to search for them. I found them
clearer than this one.
Quoted message said:
Quoted message said:
Each human has some 30000 different genes. Each gene is
duplicated on one of our 23 pairs of chromosomes. The
genes cooperate to make us humans. Without cooperation
there would not be species only be a continuity of more or
less different individuals.
Genes has vanities called alleles. Repressor and
promotor genes regulate a gene on the same chromosome.
But, an allele can also cooperate with other alleles in
a group where each member is located on a different
chromosome pair.
Geographical isolation is widely be lived to cause new
species but it is instead speciation that cause
reproductive isolation. A small population does not
speciate instead speciation shrink a large population.
A new species acquire new alleles simultaneously in each
gen in a group. There is born one first individual
bringing it all together who becomes a parent to all.
Quoted message said:variation in breading opportunities.
Male and female individuals behave differently at
creation.
Quoted message said:viability are exactly the same.
Quoted message said:while every female get a nearly equal number of offspring,
low variance.
Quoted message said:without speciation. The deer flock, the harem and stars in
music, film or fashion.
The alleles in a group are always dominant and thus an
individual can miss one allele in each pair without losing
fitness. Phenotype remain unaffected while the ability to
sire viable offspring decreases.
At creation the first individual has only one copy of each
allele in the group. There is a requirement on viability
for the first males spreading a new group. Each male must
be able to father so many children as to assure at least
one male offspring with all cooperating alleles or
population shrink.
There is no distinct ending time for a speciation event
only an increasing measure of homozygousy. After some time
the new alleles are present in both chromosomes in each
involved pair in almost all individuals.
At a low mutation rate a first individual of a new species
is highly unlikely to appear. The probability for creation
increases as the product of the mutation rates for all
involved genes in the allele group.
Assume that all genes have the same mutation rate. The
probability for a specific creation event then depends on
the mutation rate as some polynomial, the square, the cube
or some higher power polynomial.
Mats Liljedahl
I'll limit my comment to the final paragraph. I agree with
Mats that speciation requires at least two mutations. One or
more are required to adapt the species to its new niche,
plus one or more are required to provide reproductive
isolation from the parent. And, I will accept his assumption
that fitness is lowered unless ALL of the genes in an
"allele group" are changed to the new wild form.
This is an old problem - how to cross a valley in a fitness
landscape. Mats' idea is that you "jump" across the valley
by mutating all of the genes in the group at one time in one
individual. This is an unlikely process - as Mats points
out, the probability will be proportional to the Nth power
of the mutation rate if there are N genes to be changed. My
intuition tells me that "unlikely" should be read as
"impossible" for N > 2.
Since I have been thinking lately about an analogy between
chemical kinetics and evolutionary kinetics, it occurred to
me that there is a similar problem with simultaneity in
reactions such as 2H2 + O2 -> 2H2O. This appears to require
a trimolecular collision, which is so unlikely as to seem
impossible. So, how does the reaction happen? The reaction
actually takes place as a sequence of bimolecular reactions
involving unstable intermediates such as O:, H:, and HO:.
What does this have to do with genetics? Well, I am
suggesting that Mats' N simultaneous mutations is less
likely than a sequence of N sequential mutations separated
by slightly unfit intermediates. That is, in my analogy
between chemistry and genetics, I match unstable molecules
with unfit individuals. By an analogy with Boltzman's law,
I assume that moderately unfit individuals are only
moderately rare.
You don't have to jump the valley. You can walk into it, as
long as you don't try to linger there for more than a few
generations.
