I think Percy thinks he has a warrant with his thermal equilibrium (potential energy) model. But I will show in my coming reply to him where I think he misses the mark.
Selective pressures can cause change if the net pressure to change is positive or negative (data).
Selective pressures can be equal and opposite at which point they effectively cancel each other out. (warrant)
As change occurs, the strength of opposing selective pressures can increase (warrant)
Conclusion: Change can continue occurring until the strength of the opposing selective pressures become equal and opposite. At this point the net pressure to change is neither positive nor negative so change does not occur. When change does not occur it is called stasis. Removing, changing or adding a selective pressure could lead to the net pressure being nonzero and thus lead to change.
1.) Ideal genomes don't exist in nature. Dwise one seemed to understand that when he qualified it in one or two of his postings... Then he went back to an ideal genome with one set point. I believe for any given enviroment there are so many workable gene and trait conbinations that the use of ideal genome is meaningless/inapplicable.
No - but evolution isn't about ideal genomes, it's about populations moving towards an evolutionarily stable state. Populations probably never achieve a perfectly evolutionarily stable state but from generation to generation they jump around this state and the average is the evolutionarily stable state. It doesn't help that in the real world what the stable state actually is changes with each generation either. However, the stable state itself can find itself quite stable, hovering around an average as it were. And so we end up with a multidimensional model of population change.
We call this hovering about 'stasis' since no generally observable change is happening when considered over many generations.
2.) Negative feedback mechanisms are specific/limited. I don't think Dwise1 or anyone else has shown/identified a general negative feedback mechanism.
Look at a jungle or dense forest. There is a clear pressure towards driving trees to be tall - they need the sunlight and other trees might block some of that. However, there is a pressure against being too tall. Being too tall gives rise to stability issues, and nutrient transport issues. The taller a tree, the less stable and the more difficult it is to get nutrients from the ground to the topmost. The advantage of getting all the sunlight a tree needs is pitted against the disadvantage of getting nutrients and being upright. Eventually the disadvantage of getting taller will outweigh the advantage of getting taller and this stabilises things.
If a population of trees is a too tall on average the next generation will be less tall. If too short, the next generation will be taller. There may well be an evolutionarily stable state of some tall trees and some short trees. The iterated prisonner's dilemma can give some more insight into ESS (examine the Monte Carlo conclusions)
I think most evolutionists equate Evolution withchange That's how it is refered to in every dictionary I looked at...and in the thesauruses too (Evolution is not synomynous with adaption). Nowhere is it equated with adaptation. Adaptation is listed as an aspect of evolution, but that's it...Development and progressive change were common terms used there.
Evolution is hereditary change in a population over generations. Natural selection is a mechanism that gives rise to change that is adaptive. If we could remove natural selection we would not have adaptation but we would still have evolution. Since it is not possible to remove natural selection - evolution and adaptation go hand in hand of course. Evolution is not synonymous with adaptation however...more adaptation is the result of evolution because of natural selection.
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