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Author Topic:   When does a species undergoing natural selection, change more?
dwise1
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Posts: 5930
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Message 11 of 21 (812750)
06-20-2017 12:38 AM
Reply to: Message 1 by aristotle
06-16-2017 5:18 AM


aristotle, in the Nothing in biology makes sense except in the light of evolution. topic, Message 495, you brag:
I have studied evolution a long time, learned a lot about it, ...
So why is it that you had never learned about fitness, one of the most basic concepts of evolution? It would be like claiming to have studied chemistry and learned a lot about it without having any clue about the most basic atomic theory.
I believe that instead, you had been learning the creationist "evolution model", which is a gross misrepresentation of evolution, so gross that it has virtually nothing to do with evolution except for its misnaming. If you really want to criticize evolution, then you should learn something about it first. Not from the creationists, because they are lying to you.
As has been explained to you already, fitness has nothing to do with "strong" or "weak" in most environmental contexts. For example you have a stronger individual who can get anything he wants from the others because he is a bully (identifiable by their yellow eyes or orange skin -- two different cultural references there). Is he more fit than his not-as-physically-strong brethren who are able to work together for their mutual survival. The big strong loner out on his own will have far less chance of producing offspring who can survive than his weaker brethren who can band together. Is being physically strong also fit? In a species of loners, yes. In a social species, not necessarily.
Nor is there any concept of "genetic perfection". Whom are you reading? What creationist cretin wrote such garbage? You are being lied to!
Now as for the varying rate of change. There was a TV popularization hosted by Christopher Reeve before his accident in which he described a varying rate of change in evolution. That didn't make any sense to me at the time, but I figured it out later. There was an article on a conference in which punctuated equilibria was presented. One of the graphics presented the gradual generational change as a series of bell curves on a sloping line.
OK, picture this in your mind. You have a population of individuals in an environment/ecology. We could think of an ideal level of adaptation, such that an individual with those characteristics would be ideally adapted to that environment. But this population is not yet ideally adapted. They form a bell curve. When they produce the next generation, that next generation forms a larger bell curve extending further in both directions, towards being less adapted and more adapted. Statistically, it is the group closed to that ideal adaptation point who survive and reproduce more, thus shifting the center of the population closer to being more adapted. The further away from being ideally adapted the population is, the more rapid their progress towards being adapted will be. Hence, they will experience faster and greater change.
Now skip to the future where the population is basically centered about that ideal adaptation level. The population's bell curve grows with each new generation and again it's the ones centered about that adaptive ideal who are the most prolific reproducers. The rate of change has slowed down to near zero as the population is in stasis.
So, what happened to the forces/processes that had produced all that rapid change in the past? Did they suddenly change or stop working? No, they are still at work. All that changed was whether they were away from or centered on the set-point, in this case the ideal adaptation level.
I was trained as a digital electronics technician specializing in power supplies (an analog system in our computer systems). In the vast majority of power supplies, you want to provide a constant output voltage regardless of how much current is being drawn by the load (ie, the system you are supplying power to). A key component of any such power supply is the voltage regulator, which basically monitors the output voltage constantly and varies its internal impedance accordingly via negative feedback.
Now here's the question: when the output voltage is being held at a constant voltage, is the voltage regulator doing its job? Obviously yes, but think about it. If we start with the voltage far from the voltage regulator's set-point, such as at power-up, the voltage regulator changes that output voltage rapidly to the set-point. And then it holds it there. In those two different cases, is the voltage regulator doing anything different? No. It is doing exactly the same thing. The only difference is how far the output voltage is from the set-point.
So are evolutionary processes doing anything different when a population is changing rapidly than when it is in stasis? No. Those evolutionary processes are doing exactly the same thing. The only difference is how far the population is from the ideal adaptation level.
Would natural selection then actually narrow the variation of species instead of broadening it, as is claimed?
Complete and utter bullshit straight from your creationist handlers.
You have mutation, recombination, and whatever else increasing genetic variation, and natural selection filtering through that. The one increases variation while the other, natural selection, decreases it. The two work in tandem with each other.
To characterize evolution as being purely natural selection is a damnable lie. To characterize evolution as being purely mutation is a damnable lie.
Please stop with your damnable lies.

This message is a reply to:
 Message 1 by aristotle, posted 06-16-2017 5:18 AM aristotle has not replied

Replies to this message:
 Message 12 by Pressie, posted 06-20-2017 7:56 AM dwise1 has not replied

  
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