HellbirdIV wrote...
inko1nsiderate wrote...
1) Evolution isn't actually survival of the fittest.
Not sure what you mean here. Perhaps I use the term in a different way than you do, because evolution isall about survival of the fittest. Can you explain what I'm seeing wrong?
Survival of the fittest is only true if you re-define what 'fittest' means for each biological system you are looking at. For instance: it is often taken to mean whoever passes on the most genetic material. This is all well and good, but it isn't strictly true either. For instance, certain traits lead to genetic dead ends but are continually passed on anyway. The reason is, that they have some horribly non-trivial way of increasing the chances of that particular phenotype being passed on by aiding the fitness of other species. In this respect, fitness can be thought of how easily your genes get passed on, but that is hardly what anyone means coloquially when they say 'survival of the fittest' because the actual way biologists use the idea includes stuff like altruism in ants allowing ants that don't strictly reproduce to ensure some of their alleles get passed on. It is a statistical thing. Some of the genes in you are in your relatives, so to increase the fitness of a particular gene, sometimes it involves helping the progeny of relatives as opposed to actually having progeny yourself.
HellbirdIV wrote...
inko1nsiderate wrote...
2)
If a species doesn't reproduce any longer, or has exceedingly long
times between generations, the evolution of the species can effectively
be zero.
Yes, that is an evolutionary dead-end. But, as I have said, evolution is a broader abstract and not limited to species. Even when a species evolution is "effectively zero", they CAN change in the future, as long as reproduction can occur (if not, they become extinct, ergo evolutionary dead end).
You miss my point. Take Leviathans, they could live for a really long time, and reproduce with small numbers. If they live on the timescale of geological years, you're never going to see enough generations of Leviathans to see any appreciable evolution. They would still be 'evolving' in principal, but for all intents and purposes they wouldn't be seen to evolve in the technical sense of the word.
HellbirdIV wrote...
inko1nsiderate wrote...
3) There is a theoretical limit in which evolution does
not happen in a population. It is called Hardy Weinberg principal.
Anyone with even a rememdial biology course should probably have heard
of it. I'm sure with a bit of information theory and statistical
mechanics, you could make analogous limits where a biological system has
reached a limit where it can no longer have a change in its overall
genetic makeup.
This discludes the constant of genetic anomalies, however. As long as reproduction occurs, mutations may occur, and mutations which benefit an individual's survival will continue.
I'm not sure what you mean by a "biological system reaching a limit", either. As far as my understanding of biology goes, it's not a matter of putting parts on top of other parts and seeing what sticks and hoping it doesn't fall apart.
I mean limit in the mathematical sense. Hardy Weinberg equilibrium is a theoretical limit, but surely there are others. And by mechanics I don't literally mean mechanical, I mean the study of physically dynamic systems and the field where ideas such as entropy come from. You can imagine a situation where some order parameter of a biological system has interactions such that it is forced back to the mean regardless of random fluctuations of genetic anomalies. This is speculation on my part, but it is at least reasonable speculation as it is a situation that can certainly exist in principal in any statistical system that is partially driven by thermodynamics.
Modifié par inko1nsiderate, 09 novembre 2012 - 09:59 .