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

”HM replied:Yes, perhaps a new thread is more appropriate, because “group selection” and “individual selection” need to be differentiated from “gene selection” and “kin selection.” It must be confusing to MartinV and his ilk that Darwinian biologists can’t agree on exactly what natural selection is and where it occurs. And, unless you invoke the selfish-gene theory, the same quandaries can be raised about evolution itself.By definition, natural selection is the possible consequence of uneven reproductive success of individuals in a population. But this does not mean that natural selection necessarily operates on the individual or its population, even though the results may occasionally point in that direction. Looking closer, as did G. C. Williams, Wm. Hamilton, R. Dawkins, et al., the actual site of natural selection can often be seen at the level of genes and their alleles (i.e., genetic evidence of strategic altruism for kin survival). “Group selection” and “species selection” (i.e., 'for the good of the group or the species') are no longer regarded as credible by most biologists, although some still claim them to be true. Furthermore, natural selection is not the only cause of evolution. Non-selective agencies like genetic drift, gene flow, and preferential mating may also cause evolution to occur.

Preferential mating is, by definition, selective. The mate's preference constitutes a selection. That's why they call it "sexual selection", after all.

Where does evolution happen? Planet Earth. Next question. No, seriously, though. Where doesn't evolution happen? It happens any time that living things are reproducing through descent via modification. I guess maybe you think you're asking an insightful question, but it sounds like a stupid one to me. Even in a population undergoing no appreciable selection, genetic drift is causing changes to the allele distribution of the population.

MartinV wrote:Another question is if Natural selection is capable of creating new species. In this case would darwinists put more stress on random mutation that makes possibilities from which natural selection can choose.

Of course there are many scientists who deny Natural selection as evolutionary force - they consider it as only maintaing force that removes extremities. Eimer, Heikertinger, Suchantke and all great men mentioned in Davison's Manifesto.

Huh? Peahens dig males with long tail feathers. Peacocks with long tail feathers therefore get to breed. Peacocks with short tail feathers don't get dates, and so don't reproduce.How in the world is this not selection?

AZPaul3 wrote:With those just getting into the swing of things I always liked to define “mutation” as the all-inclusive process of changing the genome and leave the details to come as necessary. With Natural Selection, I define this as what effect those “mutations” have on the individual and leave groups, populations, etc. for a later time.

crashfrog responded:A kind of selection is regarded as non-selective? This isn't an issue of semantics, Chiroptera. This is ol' Jocko not knowing sense from nonsense, as usual.

AZPaul3 wrote: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.

Sexual selection doesn't have anything to do with H-W equilibrium...Sexual selection is when alleles increase or decrease ...

crashfrog wrote:Preferential mate choice causes differential reproductive success; therefore, clearly, mate preference constitutes a selective force.

Doddy wrote:Mating preferences evolved via natural selection. I'd read about the Handicap Theory, if I were you.

Does the distinction "selected for" and "selected of" help the situation? That is, there is selection of genotypes for for phenotypes. And the genes that can work well with the most assortments of genes get selected (the genes that are incorperated in the most number of successful genotypes), but their success is rooted in the sum of the effects of the entire genotype on the phenotype, that is the individual.

In essence, then, anything that affects the fitness of an individual organism is "natural" selection.

The individual is, of course, the one unit that is affected by Natural Selection pressures.

Quetzal wrote:Therefore, probably from my own biases and experience, I find the use of the individual organism as the "target" of the selective filter to be the most relevant.

Percy wrote:In other words, your understanding of natural selection differs from both creationists and evolutionists. You might want to rethink things.

crashfrog wrote:You introduce an antibiotic into a lawn of E. coli. Resistant individuals live but nonresistant individuals die.

Modulous replied:Actually, where selection can or cannot occur is one of those real controversies that biology has had. Here is Richard Dawkins:

quote:

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Dawkins, in The Selfish Gene writes:

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I shall argue that the fundamental unit of selection, and therefore of self-interest, is not the species, nor the group, nor even, strictly, the individual. It is the gene, the unit of heredity.

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