I think we may be talking past each other again.
quote:
If you define Natural Selection with variation as is common, then you would tend to ignore the action of environmental factors on an organism. There is no description in the literature of Natural Selection like: Light (environment) falls on the photosynthetic cells of a plant (organism) which contributes to it's reproduction (is selected in). Tend to ignore.
Since natural selection IS the action of environmental factors on an organism, it would be hard to ignore. I agree with you that there is no description of natural selection as you posted, because what you posted isn't natural selection. When light falls on the chloroplasts of a plant, it's simply light falling on the chloroplasts of a plant - not natural selection, because there's no "selection" occurring. Where NS comes in is when, for instance, you have a plant that is adapted for a certain light level (level being an environmental factor), and the average light level changes. IF the change in light level effects the survival (or reproductive chance if you prefer) of the plant, that effect is "natural selection". If the effect is adverse, the plant might die. In this case, we say the individual plant - or better said the suite of traits that make up the phenotype of that individual plant - was "selected against". With me so far?
Note that up to now we haven't even mentioned variation. If ALL of the plants in a particular population are exactly like (no variation) our hypothetical plant above and the average light level changes with adverse effect, what do you think will happen to the
population? Since the population is made up of identical individuals, what effects one will effect them all. Hence in this case, the entire population may go extinct.
So let's introduce a simple variance - one "type" of this species is as described above (call it type A), another has a slight mutation in its chloroplasts that allows it to more efficiently process available light (call this one type B). Since they're all the same species living in the exact same spot, there's been no real advantage for one type or the other and up to now they've all been living quite happily side by side. Just that A and B are different varieties of the same plant. Some individuals are type A, some individuals are type B. Now let's change the environment (light level). We already know that type A doesn't do well in (say) low-light conditions. Just like our single type above, type A gets selected against and dies out, leaving type B all by itself. This is the most simplistic form of evolution - the change in the average frequency of alleles (types) in a population. A is gone, B is still there, evolution has occurred (in a very simple form). The mechanism that wiped out A is termed natural selection, the result of the mechanism is termed evolution.
Hope this helps rather than confusing things further.