Tautology and Natural Selection

quote:

---

Which is why, when we get back to the original discussion of "survival of the fittest" as a tautology...

---

Was ... was that a subtle way of saying we're off topic here I have been unable to see where 'survival of the fittest' is
a tautology, though. It was a phrase coined to summarise what
Darwin originally said about natural selection so maybe it's
just out-dated wrt modern definitions of fitness et al.Darwin's idea of fitness seems to me to have been an individual
quality that aided survival, and that enhanced survival probability
was considered to increase the chances of high reproductive output.Saying 'the ones that are fittest stand the best chance of
surviving' is kind of defining 'fitness' for that context.Personally I'd be interested to see the definition of reproductive
success -- that seems even more vague to me. Syamsu would
say it means to breed or not to breed

Comes back to theory vs. description though.Are there organisms that are long-lived wrt peers that
leave less offspring?--apart from humans that isJust reproducing a lot doesn't make you evolutionarly fit if
all your offpsring die within a week of birth.Fitness must be a function of both reproductive output and survival.

Yes.Within a species do you get some idividuals that produce
a lot of offspring and die young and others that produce
one or few and die old?

If 'survival' is reproductive success and 'fitness' si reproductive
success I think I can see a tautology.One of the suggestions I have made before is that it is tautlologous
only with modern conception, and that when phrased it was simply
stating a definition or summary of Darwin's natural selection
observations.Darwin focussed his attention on survival to reproduce.Before anyone starts moaning about harping on about Darwin when
ToE has moved on .... 'Survival of the fittest' was coined in
Darwin's time, and used by Darwin as a sub-title in chapters
on natural selection.Natural selection is still more about survival of the fittest
though.Extreme PoV example:Suppose you have a population with 400 variants, all of whom
have indefinite life-span and none of whom breed.Environmental factors operate such that some individuals have
a reduced survival capacity relative to others and so find it
harder or impossible to survive.Result, some of the original 400 variants disappear completely,
and the representation of others diminishes significantly.Allelic frequency in the population has changed over time.Isn't that a definition of evolution?In the above the absence of reproduction means there is no
adaptability, so many changes of environment would eventually
wipe out the whole population.It does not prevent natural selection changing the allelic
frequency of the population.

quote:

---

You really are turning into Syamsu now Peter, you have just started an argument based on a fictional hypothetical population specifically tailored to suit your point but completely divorced from anything which actually exists in the real world.

---

LOL!! Humour me for a couple of posts and we'll see whether
looking at hypothetical limit cases is worth the bother

quote:

---

How can you show that the fitness in your population is related to the genetic variation rather than anything else, given their incapacity to breed?

---

The same way you would with a breeding population -- you look
at trait frequencies as a snapshot of the population at some
point.One assumes (as is the case for real populations) that the
traits which dominate are those which confer a 'fitness'
advantage.You can apply exactly the same reasoning and analysis via
natural selection to changes in trait frequency in this limit
case, even though there is no reproduction going on.Removing survival issues and just looking at reproduction we could
have 400 variants who each produce a different number of offspring
during their maximal lifespans.If all live the same amount of time the one which reproduces
the most dominates traits set.If they do not -- a survival factor -- this changes.Survival must be a part of what fitness means.That's all I'm saying.

But then you haven't elliminated survival from the
equation -- which is what what I was trying to do
in the same way that I attempted to elliminate reproduction
from the other case.Assuming the offspring have a similar life-span the sepcies
persistence matters, doesn't it?Case A: lifespan = 1 year reproductive output = 50represents 50 organism-years ( in management terms)Case B: lifespan 100 years reproductive output 3represents 300 organism years.Reproductive output alone cannot be used as a fitness measure.Even if you just look at generation years, A above has to persist
for 100 generations to match B in persistence terms.

That's OK then ... that's all I've been saying.fitness is a function of reproductive output and survival.

But at which point during the life-time of that
generation?That was partly my point of proposing a hypothetical
immortal population. They can kill each other, or starve to
death, or such, but not die of old age.Take snapshots through time and the trait frequencies
would still be changing.For me that means that fitness/reproductive success must have
survival as one of its variables (or paramaters maybe).WoundedKing says we all knew that all along -- which makes me
wonder why this thread has gone on this long -- mind you
all the creationists DO seem to disappear in the summer

quote:

---

No problem on the lateness. I broke some handbones and wrist in car accidenct recently, so my responses may be pithy.

---

Ouch!! I sympathise, I broke my left wrist and a bone in my right
hand a couple years ago when I came off my motorbike!!!

quote:

---

How is it not tautologous if you factor in genetic drift in fitness. It seems like the theory is 'survivors survive'. How would you describe the theory?

---

It's not that survivors survive so much as those who are fitter
have a greater chance of surviving. Some very fit individuals
will still die and some less fit will still survive to breed.'Survival of the fittest' means 'Those better adapted to their
environment are more likely to survive.' The longer one survives
the more opportunity one has to breed -- I mean look at Michael Douglas

But when do you measure/assess the allelic frequency of
the generation?1 year into the life-span, 2, 10, 20 ... ?Will the allelic frequency be the same in year 0-2 as it
is in years 10-15?

I have said a few times that I view fitness to be a function
of survival and reproductive output.I do think that survival has much more of an impact than
reproductive output though (in individual and evolutionary
terms).Especially in response to environmental change.

I suppose in a real population you could take a large
sample and determine allelic or trait frequencies within
different age ranges.You could then perhaps make some comment on the 'life-cycle'
of traits.These are the things that make me feel that 'survival' is
a necessary part of any definition of 'fitness' though.

So you would only look at the individuals who are
breeding for the first time?

But you could only do that for females since you won't
necessarily know which males have bred?Or would you look at all individuals that have come to
mating age?

The reason I asked was to see whether or not I agree
with your definition of 'fitness'.The way you have suggested measuring it agrees with the way
I view fitness -- which is what I thought.By looking at which 'trait sets' have survived to maturity
you are assessing the reproductive fitness of those 'trait
sets' from the previous generation.If you were only looking at which first-timers have bred
you would be looking at reproductive output only.I think the former is a means of assessing fitness, and it
combines reproductive output and survival -- which makes
me happy.