What exactly is natural selection and precisely where does it occur?

Gerhard, don't take it personally. Popular darwinists are popular story-tellers and Gerhard you are neither of them. Gerhard, I understand your problem. You suppose that to underestand natural selection is something very challenging. Maybe it have taken lot of your time untill you comprehend what is it all about. Now you suppose nobody can underestand it as well as you do. No wonder that for metaphysical reasoning there is no place in your reasoning Gerhard. Edited by MartinV, : No reason given.

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Popular darwinists are popular story-tellers....

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And you are an unpopular story teller.Look, this is very simple. Give us your mechanism for evolutionary change, and then present evidence for your mechanism. Babbling about "spirit forces" and how "sharks and crocodiles would prevent mammalian evolution" just makes you look like a nut.

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Actually, if their god makes better pancakes, I'm totally switching sides. -- Charley the Australopithecine

The individual is, of course, the one unit that is affected by Natural Selection pressures. Even when major environmental changes occur affecting an entire species some individuals may be better constituted to survive and procreate.The individual is a “suite” of genes acting in concert. The right mix works, the wrong mix dies . as an individual. The effect is that certain mixes of genes survive, propagate and add to the mix in a population. Dawkins’ “selfish gene” phenomenon is the result.Unless, of course, Marty’s spirit force is peckish and decides to make chocolate pudding of everything.

Consider this: The Hardy-Weinberg equilibrium requires random mating in the population, otherwise its allele distribution could change if preferential or nonrandom mating occurs. I’m not talking about reproductive success here; this is not about natural selection. Sexual selection is about disturbing the H-W equilibrium, which is considered a non-selective agency of evolution. Natural selection doesn’t apply to sexual selection because natural selection is not about mating”it is about differential reproduction success.”HM

Right. That's because Hardy-Weinburg breaks down under selective conditions. The assumptions that underly H-W equilibrium are there because that's what you have to assume to take selection out of the picture. Sexual selection doesn't have anything to do with H-W equilibrium except for being one of the reasons that you'll never, ever find a population in H-W equlibrium in the real world.Sexual selection is when alleles increase or decrease depending on the attractiveness or fertility of their bearer. As such, it is clearly selective. Preferential mate choice causes differential reproductive success; therefore, clearly, mate preference constitutes a selective force.

Then you would agree that natural selection "pressurizes" all the way down to the genetic level? This is different from selecting at the level of the individual, who is only an extant collection of phenotypes, assembled to serve the needs of reproduction, which of course perpetuates those selfish genes.”HM

What you say, mon? I think you're contradicting yourself.”Hoot Mon

Only because you have no idea what you're talking about when you say "Hardy-Weinburg equilibrium." I assure you that when they cover this concept in your classes, you'll see that there's no contradiction at all in what I just said.

They don't have to be 'living' things.

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"And, lo, a great beast did stand before me, having seven heads, and on each head were there seven mouths, and in each mouth were there seventy times seven teeth. For truly there were seven times seven times seven times seventy teeth, meaning there were. . . okay, carry the three, adding twenty. . . plus that extra tooth on the third mouth of the sixth head. . . Well, there were indeed a great many teeth" - The Revelation of St. Bryce the Long-WindedHelp inform the masses - contribute to the EvoWiki today!

How does mating not get included in differential reproductive success?Of course natural selection is about mating. If nobody mates with you, it affects your reproductive success, just like being eaten or diseased does. And natural selection obviously looks at these, so why not mating?Mating preferences evolved via natural selection.I'd read about the Handicap Theory, if I were you.Edited by Doddy, : clarification

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"And, lo, a great beast did stand before me, having seven heads, and on each head were there seven mouths, and in each mouth were there seventy times seven teeth. For truly there were seven times seven times seven times seventy teeth, meaning there were. . . okay, carry the three, adding twenty. . . plus that extra tooth on the third mouth of the sixth head. . . Well, there were indeed a great many teeth" - The Revelation of St. Bryce the Long-WindedHelp inform the masses - contribute to the EvoWiki today!

Good point.

Sure, Hoot, you could go that way. But, I won’t.Yes, genotype + environment = phenotype. All this means, in the grand picture, is that I am me. My “individual” is a unique phenotype based upon a unique genotype. I am a unique mixture of genes. I, the individual, am my genes.To be religious about it, none come unto my genotype but through me.Natural Selection has no effect upon my genes save through its effect upon me the individual. I am blessed by Ol’ Mom Nature to have been conceived as a “fit” specimen of my species. My suite of genes has been found to convey survivability and reproduction of this resultant individual within this environment. Natural Selection did not select against me as an individual (suite of genes) which means a good portion of my genes have been passed on to my progeny. Poor kids. But the point is this, between genotype and individual there is no distinction. We are each, they.Clear as mud, I know, but it sounded good when I wrote it.To argue that selection operates on the gene and not the individual or on the individual and not the gene is incorrect. We are indistinguishable. Dawkins sees a selfish gene. I see an entire suite of selfish genes . me.

I don't see how that differentiates the genetic level from the individual level. Can you elaborate? They still seem the same to me.

I appologise in advance. I'm feeling verbose.Where to start?The beta Globin Gene cluster is one of the most selfish suites of genes in all of mammalian history.“Don’t include me and guess what?...You don’t get to live! You don’t even get to get born!”Bunch of egotistical plicks!Natural Selection doesn’t get to do much with bGGC because all by itself it just kinda lays there on the ground and rots. In a package of other equally selfish genes, however, it can, and periodically does, get to be carried around in a warm living thing with duplicates of itself in other packages comprising other parts of the same warm living thing.Not that bGGC would acknowledge this but in fact without the rest of the package of equally selfish genes bGGC is a rather useless glob of goo of no use to anyone. Other than its egocentric attitude the other major attribute bGGC has is the fact that without it the rest of the package of genes doesn’t get to go anywhere or do anything and just kinda lays on the ground and rots. So bGGC gets invited into all the packages (those that want to go anywhere, do anything and have some fun, like maybe, live) and all the various suites of genes get to show off, strut their stuff and make a furry fuzzy mammal.Now one specific glob of bGGC (we’ll call him Bob) was a bit unique. He wasn’t like all the other bGGCs. He was special. He could make the most efficient hemoglobin there ever was in all the world. He was good. Unfortunately, he also wasn’t very choosy about what package of other selfish genes to go party with. Not that he had much choice, his family is on the “A” list, after all, he did got invited and since all the other parties were getting their own bGGCs he figured he would go so he went. For a while Bob had a grand old time with his pals showing off, strutting his stuff, doing his thing, making copies of himself billions upon billions of times with the rest of the gang until they had themselves a nice furry fuzzy mammal to ride around in.The problem started with Bob’s new acquaintance, Hox. Seems Hox was a bit of a laggard and as it turned out had neglected to copy the plans for that right front leg. Well it wasn’t long before Natural Selection showed up with its glowing green eyes, sharp salivating fangs and Bob and Hox and all the rest of the gang ended up being ripped apart by digestive juices.Now if Bob had been invited to one of those other parties, maybe the one with Hox’s sister Hoxanna, who was as unique as Bob in her own abilities (she was a most brilliant engineer and never forgot anything) that party could have built themselves the strongest fastest bestest furry fuzzy mammal of them all. But no. Natural Selection didn’t know about Bob’s greater abilities, couldn’t care less in fact. All Natural Selection knew was that the furry fuzzy mammal that Bob and his party put together was slow, hobbling and delicious. Regardless of Bob’s unique and superior attributes, the entire gang, all the various suites of selfish genes working in concert with their abilities, created an individual that Natural Selection decided to eat.It is not the individual gene nor even small suites of genes like bGGC that Natural Selection targets. It is the entire package, the individual, that makes it or doesn’t.

I'm not so much going to disagree and elaborate and get to a slightly different conclusion.It's certainly true that the individual events that add up to selection happen on an individual level. But selection needs to work in aggregate over the lifetimes of many individuals. For asexually reproducing creatures where the entire package of genes is passed on it may make sense to look at the whole package of genes. But in secually reproducing creatures where genes get mixed up and reshuffled in every reproductive event such an approach can't work.Since whatever is being selected must be somethng that can be inherited and must be something that we can find in many individuals, it makes more sense to look at genes. The view of a single gene working in isolation is certainly oversimplified but - for sexually producing organisms - it comes closer to what is actually going on.On the grand scale your selfish genes are in a temporary alliance. Your success contributes to the spread of most, maybe all, of them. But it isn't enough in itself - you're a transitory event, unlikely to be repeated. Your genes must prove themselves successful in many different alliances to spread through the entire population.The individual events that make up selection happen on the scale of individuals. But it is the sum of those events that really matters on an evolutionary scale.