The encroaching is Darwin's justification for including variation in Natural Selection.
It is? Could you select the specific page references supporting this?
I think what you are talking about is competition. Why you would use a different word I don't know. May I paraphrase what I think Darwinism is saying?
When there is competition (of any kind) between organisms then some will survive and pass their traits to offspring (reproduce) and some will not. Part of what may determine which ones do and which ones don't (besides dumb luck and any number of other purely random affects) is the fact that they aren't all the same (variation).
First of all you should acknowledge that it is worthwile to look at how an organism reproduces. That is the subjectmatter of a cutdown theory of selection. How an organisms reproduces is that there are relations to the environment that contribute to reproduction, and relations to the environment that diminish reproduction (this I then call positive and negative selective pressures). These relationships make for a chance of reproduction of the organism. (which I call it's fitness)
Is anyone arguing with this? In what way haven't you just reproduced a short form of Darwinism?
One of the negative selective factors on an organism might be competition from other organisms in the population with a differing trait. (which is then a negative selective factor). The organism may also be limited in it's production by being preyed upon by another organism from a different species. (which is another negative selective factor). There is no fundamental difference in the relationship between an organism of a different species, and an organism with a differing trait in it's own population, they both diminish the chance of reproduction. (the organism is selected against in relation to both those very differerent organisms). When an organism is preyed on, exactly the same thing happened as when a variant takes it resources. The reproductive success of those that prey is increased, as well as the reproductive success of the variant that took the food.
Again, I don't see any disagreement. How is this different. I think it is insightful to note that as far as each individual is concerned everything is the environment including other members of it's species and all other species.
Now why should I want to compare the reproducionrates of the organism with the variant? And what about comparing the reproductionrate of the organism with the organism that's preying on it? I don't know why.
From one point of view you may not care about this comparison. However, when we are interested in the alle frequencies in a breeding population we are interested. So from the indivdual point of view it is all competition(a bit extreme but leave it for nw). However, when we want to see how evolution progresses then then the differences are important.
To put this in an extreme form should provide some insight. Why not compare the rate of reproduction of frogs and elephants as well? Why is that so bizarre?
First, it's bizarre because the frogs and elephants each have their different way of reproducing. So then Natural Selection depends on the difference between organism being very small, otherwise if the difference were big, as big as that between frogs and elephants, then it would be bizarre.
Second, the frogs and elephants do not influence each other's rate of reproduction at all.
No, natural selection (it is not appropriate to capitalize it) does not depend on the variations being small. The frog and elephant example makes it appear that way
because they don't seem to influence each other's rate of production at all. However, wolfs and rabbit also exhibit "large" variation and they do influence each others rate of reproduction.
It's not neccesarily true for a variant of the same population to influence the rate of reproduction of the organism in question (to encroach). For some part like elephants and frogs, each variant can have their own niche, so encroachment can be no justification for comparing.
Again, is encroachment any different from competition here? And of course it is not neccesarily true for a variant of the same population to influence the rate of reproduction of others of it's species. Some variations are neutral and may or may not spread through the poplution. Later these variations may make a difference and selction will start to influence genetic frequencies. How is this different?
Differences between variants being small, is a largely subjective argument, which can't be part of a theory. There is no law of gradualism in nature. Mutations are discrete, and the consequences for reproduction eratic with different mutations. I guess the gradualism between variants that is there, is more likely to be part of an acquired trait for gradualism, rather then that gradualism is a fundamental property of heriditary material. I think that the subjective gradualism in the definition of Natural Selection, is what caused Darwinists to oppose Mendellian genetics for up to 72 years.
What does the first sentence mean? Why do you think it is saying something true?
Gradualism is not a fundamental property of heriditary material. (see information on HOX genes). And even is it is? So what? Lots of large changes have been shown to occur reasonably gradually.
So if I would compare then I would get the proportions in the population. But then this can be deceptive beacause the variants may be to some extent in separate populations, have their own niche.
What are your trying to say here? I think you are saying they may be starting to speciate. So?
This has not explained anything. It is a simplified rehash of Darwinism. I still don't see the difference you think is there.
{Fixed 2 quote boxes, and 1 "bolding" - People, use the preview button before you submit - Adminnemooseus}
[This message has been edited by Adminnemooseus, 06-09-2003]
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