Is there more than one definition of natural selection?

Do I understand the "pinciple"? I do, yes. I wonder if you do? Ignore that fact? No. In fact you'll notice that I had to remind you of that fact, to counter your hilarious misunderstanding that genes expressed their products completely on their own, absent any of the structures you've listed above.It seems like in the intervening time between these two messages, you completely forgot what we were talking about. Time's ravages, I guess. I agree. You're unable to understand the terms that have already been set before you. It was my hope that another term that you didn't understand would be enough to shock you into educating yourself, and correcting your many misunderstandings of biological processes. I see that I was wrong. Everybody's clear on those terms but you. I realize that being a limnologist implies being a bit of a polymath, but that doesn't seem to be the case here. I wonder if it's even possible for you to understand, at this point, that people could have a clearer idea of these things than you do. With you? We've already done that. Don't you remember?

Wounded King,I loved the hooty owl. Very creative.Could you elaborate on this: How are they different? So you see all other “forces” of evolution as subsumed by a master-force you call natural selection? Your relative weighting of these forces seem paleo-Darwinian to me.”HM

Oh, I thought they had cell phones for dialing up the ribosomes to express their digital codes. You mean it's not a broadband kind of operation? I sometimes wonder that myself.”HM

Glib as usual. Do you have answers to my questions yet? You said you'd go think about it. Did you remember to think about the questions, or did you just spend all your time working on your comedy act?

Precisely. It is all under the umbrella of Natural Selection.Hoot, I fail to see why you insist on separating Sexual Selection out from under the umbrella of Natural Selection. I have seen snippets here and there but nowhere in either of the threads we've spawned so far on this subject exactly why you want to make this separation.Can you clearly define where the differences are as you see them? Why would sexual selection not be considered another form of Natural Selection?

quote:

---

So, I have another question for you. Back in Message 32 I mentioned this observation of counter-processing by two evolutionary geneticists, Hartl & Jones:

---

If a detrimental allele is maintained in a population by mutation pressure alone, so what? Why do we have to invent some arbitrary "process" for this? Isn't knowing that mutation occurs enough?

quote:

---

I’ve been arguing that all five processes are possible along the course of an evolutionary continuum. What do you think about it?

---

I'm just a simple creature.This is all too abstract and cerebral for me.A

---

Natural Selection is not Evolution-- R.A. Fisher

Allow me to try to address your questions this way. You said in Message 46: I’ll focus on this sentence to try to straighten out one aspect of this issue.When I read this sentence I become immediately suspicious about the way you describe NS. I don’t understand your principles and assumptions behind this statement. Why do you say that natural selection impacts an organism’s reproductive success? Why wouldn’t you say instead, and more correctly, that natural selection IS the differential reproductive success amongst individuals of a population. The way you choose to see NS would allow for, say, bottlenecking”a kind of random genetic drift”to be regarded as a kind of natural selection. I want to separate drift from selection for one good reason: they are NOT the same thing, they act differently on populations. And for the same good reason, I want separate nonrandom mating from natural selection. I’ll agree that nonrandom mating may affect a population’s differential reproductive success, and ultimately even change its allele frequencies. But it doesn’t have to, not necessarily. It could change allele frequencies all on its own.You might have a bottlenecked population in which all individuals mate successfully and produce equal numbers of offsrping. Why not? In this case an allele frequency redistrubtion may have happened without any NS at all. Now, I would agree that NS could eventually play a role in an evolutionary continuum. But you want to see it an umbrella principle, as if to subordinate all other evolutionary "forces." So I'm questioning the validity of your principle and the assumptions you must make to invoke it.”HM

Because while you can have non-random mating without sexual selection you can't have sexual selection without non-random mating. The difference is in the non-randomness of the mating acting upon heritable traits.If females chose not to mate with males of a certain colour, but that colouration was due to an entirely random environmental factor, then you would have non-random mating which would not effect any meaningful selection. Um, no. Quite clearly not. I see all the selective forces which act upon heritable genetic chracteristics to influence allele frequencies in subsequent generations as Natural selection and I see Natural selection to be one of the factors in evolution, but along with mutation it is one of the most important ones. I already agreed previously that mutation, gene flow and genetic drift could all effect
changes in allele in a population, and thereby evolution, and that these were distinct from natural selection by way of being indiscriminate as to the genetic constitution of the population and organisms.I will caveat that by saying that mutation can be affected by the genetic makeup of an organism, and there is a good case to be made for natural selection having produced a number of strategies for modifying the rates at which variation is produced in some areas. Equally there may be genetic bases which predispose an organism to more frequent migration from its original population, but these are unnecessary complexities to the basic concept of these forces being essentially non-selective.Can you give us any idea where you came up with what you put forward as my position?TTFN,WK

Hi Hoot Mon,Concerning sexual selection, this diagram represents the mainstream view, and also the view shared by everyone else in this thread:Concerning the definition of natural selection, it can be used in two different ways, and which definition is in play is usually clear from context. It can refer to the mechanisms of selection, or it can refer to the process by which favorable heritable variation becomes more prevalent in a population. Many discussions of natural selection slip back and forth seamlessly between the two definitions while still retaining clarity.--Percy

Percy wrote: Sure, nonrandom mating can be seen as subordinate to natural selection, but it doesn't always have to play that role? Why should it? Nonrandom mating is specified by geneticists as a separate condition that may affect the Hardy-Weinberg equilibrium. OK. You are claiming that natural selection embraces two seamless-but-opposing concepts: selection mechanism v. fitness variation. Those are causes of natural selection. I’m only claiming that natural selection is, by formal definition, the differential reproductive success amongst individuals of a population. Whatever else there is to it may be of interest, but they would be only technical explanations for how a population experiences differential reproductive success amongst its individuals. Yes, nonrandom mating may be a cause of natural selection, or it might be a co-process of it, or a counter-process, or it might even be an independent process, contributing to changes of allele frequencies on it own.”HM

Now, wait a minute here. You seem to view sexual selection as an outcome, not a process. The process, as you see it, is nonrandom mating. I see them as the same thing, just as I see natural selection as the same thing as differential reproductive success amongst individuals of a population. Well . yes! Especially when those heritable traits are actually allele frequency distributions. Whoa! Please understand that natural selection doesn’t have any strategies, and it didn’t “produce” any either. If you want to go looking for strategies, my friend, I’d head on down to the gene pool.*”HM*Please remember, I don't like to use smilies, but my hoot owl is always winking.

Because I see Natural Selection more as a process then an outcome. To me, the outcome is Evolution, a change in allele frequency in the population over generations.In Edit: The processes of Natural Selection yield differential reproductive success. Or not, as we will see later.Differential reproductive success can be impacted by lots of different processes, sexual selection being one of them; being eaten by predators because I’m one of the slow runners in the population is another. Different mechanisms, yes, but the processes of Natural Selection in action in both cases. What is the reason for the bottleneck? An Ice age? A new predator? One of the other processes of Natural Selection acting in the extreme? One of Quetzal’s “field of bullets” scenarios?The processes of Natural Selection can create these bottlenecks. Drift could be an outcome of the process.I understand separating discriminate from indiscriminate processes (thank you Dr. Millstein). I will give Quetzal his due in seeing the "field of bullets" differentiated from discriminate selective pressures, though just barely. And I can see your separation of drift from selection in that drift is an indiscriminate process. Because it is an indiscriminate process? No, that can’t be it.Because the sexual selective process is different from, say, an environmental selective process? Or a “Microbial” selective process? Do not all have equally the effect of changing allele frequency in the next generation? Are not all these types of “selections” based upon phenotype and are they not all types of discriminate sampling? OK, not too likely, but why not? It’s a good thought experiment.So, due to the lower availability of mates than would be available in a larger population the process of Sexual Selection results in everyone being selected. This is what I don’t see. If the sexual selection process selects everyone in this unique situation how is this not Natural Selection and in some way any different than if the process yielded some differential among the breeders? If only one individual had some slight differential in success, would this then constitute Natural Selection where 0 differential does not?Edited by AZPaul3, : You never get these ideas while your typing or going over your 16th proofread. Only after submitting does the idea hit you like a finger in a light socket.Edited by AZPaul3, : Then, again, sometimes you have to correct a whopping stupidity.

No matter how many times you say this simply saying it will not make it true. Sexual selection is a process which can only occur when there is a genetic basis for the selection. Non-random mating can occur on the basis of any difference, including acquired characteristics. Well maybe that is your problem, you are doing what you accuse others of. While you bang on about people treating mutation and genetic drift as part of natural selection you are happily lumping all non-random mating into sexual selection whether there is a genetic basis for the non-random mating or not.The same environmental factor can be selective in one population and not in another provided there is some relevant genetic substrate to act upon. So what may provide selective pressure in one case may simply be one element contributing to the random sampling of genetic drift in another. These things are highly context dependent, and we may never fully understand the whole context. Um no. An allele is heritable an allele frequency distribution less so , at the organismal level at least. I have never disagreed with your definition of NS as differential reproductive success amongst individuals of a population, although I might add something to say about the basis being heritable traits/characteristics into the mix, only with your persistent contention that this somehow didn't subsume sexual selection. As I said previously a more narrowly defined definition of NS would give you a case to discriminate between NS and SS but your definition does not. In fact your definition would agree with my own conception, and disagre with Percy's diagram, in that artificial selection should also be subsumed by NS. Well since I clearly didn't say that it seems redundant to point it out, but you keep making things up for me to say and then rebutting them if it makes you happy. Well I don't agree. Clearly the genetic basis of any such feature is genetic, how could it not be. But the persistence and and maintenance of such features as functional units is the result of NS. By keeping alive the genetic variation encompassing the elements of that feature and assuming such features do not arise instanta but over time with the accumulation and rearrangements of several genetic elements, NS clearly plays a role in the production of such features, but not a creative role.TTFN,WK

Nonrandom mating is not the same thing as sexual selection. Many people choose their mates from the pool that is their workplace. This is non random mating since not all potential mates have an equal chance of being chosen, since Japanese people are unlikely to be chosen by virtue of the distance it would take to meet them.This is nonrandom mating, but it is not sexual selection.Sexual selection occurs when some heritable trait helps an organism to attract or otherwise acquire a mate. This is certainly nonrandom mating, but not all nonrandom mating is sexual selection. And it is! Nonrandom mating is not shown in the diagram for a reason. Nonrandom mating can occur because of heritable traits, geography, chronology and other concerns.

Wait one, Mod. Are you saying that since the Peahen has not seen every cock in existence everywhere on the planet that any mating that takes place is non-random but not Sexual Selection?Since when did Sexual Selection have to include all members of the species everywhere? Is it not sufficient for the hen to select one of the cocks from those few available in the vicinity to qualify as Sexual Selection?