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Can sexual selection cause a decline in evolutionary fitness?

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From evolutionary biologist Richard O. Prum at the New York Times:

Are These Birds Too Sexy to Survive? Natural selection can’t explain this.

Wow. Careers have been wrecked over such departures from dogma.

Most biologists believe that these mechanisms always work in concert — that sex appeal is the sign of an objectively better mate, one with better genes or in better condition. But the wing songs of the club-winged manakin provide new insights that contradict this conventional wisdom. Instead of ensuring that organisms are on an inexorable path to self-improvement, mate choice can drive a species into what I call maladaptive decadence — a decline in survival and fecundity of the entire species. It may even lead to extinction.

But wait! Don’t most of us know guys like that? Ask around at half-way houses.

Evolved decadence may turn out to be common. For instance, the male Wilson’s bird of paradise has a bright blue, bald crown — a disadvantage when hiding from predators, but handy when it comes to courting a female. The females have the same risky tonsure, albeit in a deeper violet hue. The male wire-tailed manakin has elongated tail feathers, which he swipes across the face of the female during courtship, and which may impede flight. Once again, the females sport the same long feathers. Even the peafowl has a longer tail than she needs.More.

Even we didn’t realize that Darwinism was that rigid in its thinking. Again, wow. 😉

See also: Can sex explain evolution?

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Comments
hammaspeikko: I'm sure you've read your share of books. We here at UD have also read our share of books. That doesn't mean we accept as proven, or reasonable, all that's found there. For example, eight years ago we had a discussion here about Biston bistuleria, the peppered moth. It was in the news at the time. One of the regular UD posters, a UD supporter, said he had taken an online course given by a Berkeley professor, and that natural selection is all about "changing allele frequency." You sound just like this poster. Well, I disagreed. I had serious doubts about the whole notion of "changing allele frequencies." Now the 'peppered moth' is an 'icon of evolution.' This is what Darwinists point to when defending and validating their theory. Within the last few months a study came out on Biston bistuleria. It turns out that what caused the transition from the 'dark' to 'light' form was a transposon located within an intron. Now 'introns' are normally classified as part of "junk DNA." And, on top of that, it has been known since the 40's that 'transposons' exhibit 'non-random' behavior. So, the ICON of "changing allele frequencies" turns out to be a 'transposon' finding its way into some "junk DNA"--that is, a non-random change affecting non-coding DNA. Isn't that about as far away from "changing allele frequencies" as you can get? Reading to us from books won't carry the day here at UD. Nice sounding words aren't the same thing as 'proof.' And there is no 'proof' for "changing allele frequencies"; at least not in the case of the 'poster child' of such assertions. Now, what about the demonstrated incoherence of the term "fitness"? Don't you see how vacuous a term it is? The lesson of the 'peppered moth' study is this: you can run, but you can't hide. That is, now that whole genome analysis is being done on a grand scale, we'll actually end up knowing what really goes on within the genome. My prediction has been, and continues to be, that Darwinism cannot hold up to what will be found. And neutral drift is but the next idea to be shut down by genomic studies.PaV
May 12, 2017
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PaV and Andrew, I really don't understand your confusion. Selection is nothing more or less than a change in allele frequency within the population. This can occur when populations are growing, remain stable, or decline.hammaspeikko
May 12, 2017
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Are you suggesting that post facto labels are meaningless?
I'm observing the word "selection" is rendered meaningless when it doesn't mean a selection process with selection criteria and evaluation. Andrewasauber
May 12, 2017
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hammaspeikko:
How so? It can result in a phenotype becoming quickly fixed in a population even if the population is declining. That is all selection “promises”. Remember. Evolution 101.
How so? I would think this would be evident to you. "Fitness" is, according to what you've just written, disconnected from the normal definition of "fitness." Per your usage, "fitness" is an equivocal term. IOW, here's what you're saying: "'Fitness' means that an organism becomes more vigorous and well-adapted to its environment--as evidenced by its higher reproductive rate. That is, unless it becomes less vigorous, and less well-adapted to its environment though still enjoying a higher reproductive rate." This is rubbish, no?PaV
May 12, 2017
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PaV:
This makes “fitness” a completely meaningless term.
How so? It can result in a phenotype becoming quickly fixed in a population even if the population is declining. That is all selection "promises". Remember. Evolution 101. Andrew:
This makes “selection” a completely meaningless term, since you’re telling me there’s no selection criteria, just a post facto label.
Are you suggesting that post facto labels are meaningless?hammaspeikko
May 12, 2017
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Whether or not selection has occurred is based on the outcome, not any past desire.
This makes "selection" a completely meaningless term, since you're telling me there's no selection criteria, just a post facto label. Andrewasauber
May 12, 2017
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hammaspeiko:
No. You are exactly correct. Phenotype A’s reproductive rate is higher than phenotype B’s. Therefore it is more fit. Fitness has nothing to do with whether or not the population as a whole is increasing or decreasing.
This makes "fitness" a completely meaningless term.PaV
May 12, 2017
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PaV et al, no, the fittest are not the ones who survive. Even the less fit can survive. Fitness is nothing more than a measure of differential rates of reproduction amongst individual in a population. Phenotypes that pass along their genes to subsequent generations at a higher rate than other phenotypes is more fit than the other phenotypes. It can only be determined after the fact. This really is evolution 101 stuff. Selection always increases fitness, even in a rapidly declining population. If there is no phenotype linked differential reproduction, there is no selection.
Well, because of the tree disease, the reproduction rate of Phenotype A is decreased by only 50%, and that of B by 75%. Hence, by DEFINITION, Phenotype A is more “fit.” Q.E.D. Something is wrong here, isn’t it?
No. You are exactly correct. Phenotype A's reproductive rate is higher than phenotype B's. Therefore it is more fit. Fitness has nothing to do with whether or not the population as a whole is increasing or decreasing. Andrew:
It almost sounds like natural selection (whatever animates it) has a preference for Life.
No preference at all. Whether or not selection has occurred is based on the outcome, not any past desire.hammaspeikko
May 11, 2017
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hammaspeiko:
That is why I said that selection does not reduce fitness. It can only increase it. Otherwise, by definition, it is not selection.
IOW, evolution is the survival of the fittest. And therefore, by definition, those who survive are the fittest. And how do we know they're the fittest? They survived!! This is circular logic, typical of evolutionists. Here's what I mean. I'll use your example of Phenotypes A and B. You wrote: For example, let’s assume there are two phenotype in a population. 1) an environmental change results in a significant reduction in reproduction rates for both phenotypes 2) phenotype A experiences a 50% decrease in reproduction. 2) phenotype B experiences a 75% decrease in reproduction. Okay. So, let's say there was a disease that affected certain trees in the area, and this disease was found only in its uppermost parts. Now, phenotype A is a bird species with smaller wings, and less adapted to flight. So, it spends more of its time feeding on the ground, and less in the trees, especially in the top most portions of the tree. Now, phenotype B is the same species, but with slightly larger wings, and better adapted to flight. It feeds on the tree and spends more time in the trees than on the ground, and especially more time in the top part of the trees. Well, because of the tree disease, the reproduction rate of Phenotype A is decreased by only 50%, and that of B by 75%. Hence, by DEFINITION, Phenotype A is more "fit." Q.E.D. Something is wrong here, isn't it?PaV
May 11, 2017
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It almost sounds like natural selection (whatever animates it) has a preference for Life. Andrewasauber
May 11, 2017
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To answer myself I suppose the argument would be: "anything below minimum functionality will automatically be selected against", so I guess the issue would be more along the lines of "non-local" or minimum general functionality, i.e. how quickly does a genotype become critically incapable of maintaining population size against probable/inevitable fluctuations in selection parameters. A little more nuanced.LocalMinimum
May 11, 2017
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hammaspeikko,
If it is decreasing fitness then it isn’t selection.
What impels natural forces to "select" increasing fitness over decreasing fitness? Andrewasauber
May 10, 2017
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hammaspeikko: So, fitness excludes any notion of sufficient functionality/survivability? What an incredible misnomer Darwin wielded. I suppose you can easily become fit for extinction.LocalMinimum
May 10, 2017
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Anthropic, fitness and long term survival are not the same thing. Fitness of a phenotype can increase over a couple generations even if the reproductive rate dramatically decreases. For fitness of a specific phenotype to increase, all that must occur is for the reproductive rate of those with this phenotype to increase relative to those without this phenotype. For example, let's assume there are two phenotype in a population. 1) an environmental change results in a significant reduction in reproduction rates for both phenotypes 2) phenotype A experiences a 50% decrease in reproduction. 2) phenotype B experiences a 75% decrease in reproduction. Because fitness is measured relative to the rest of the population, phenotype A has increased in fitness even though it has seen a dramatic reduction in reproductive rate. This is evolution 101 stuff. And, as you can imagine, continuing along this course could result in the extinction of the population. That is why I said that selection does not reduce fitness. It can only increase it. Otherwise, by definition, it is not selection. But selection also does not guarantee survival. If selection pressures are very high over a short period of time, the natural genetic variation that has built up in a population over time will be significantly reduced. Any further pressures could result in the population not surviving. Evolution 101 again. There are many things that evolution doesn't explain. But this isn't one of them.hammaspeikko
May 9, 2017
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Yes. Sexual selection increases fitness. Unless, of course, it leads to an evolutionary dead end. Either way, evolution explains it, just as it explains everything that happens. Uh-huh.anthropic
May 9, 2017
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Wow. Careers have been wrecked over such departures from dogma.
Scientists who agree with evolution say this all the time without it hurting their career. Larry Moran is an example. His career may be winding down, but that is due to his age, not his opinions on evolution. With respect to sexual selection decreasing fitness, I don't see how that is possible. Sexual selection is a form of natural selection that is caused by differential mate selection. If it is decreasing fitness then it isn't selection. Fitness is measured relative to the entire population. Even if mate selection results in lower fecundity from one generation to the next, this could still be an increase in fitness if the trait selected for still has a higher fecundity than those without that trait. However, it is quite possible that selection, sexual or otherwise, can lead to an evolutionary dead end. This is fully consistent with evolutionary theory.hammaspeikko
May 9, 2017
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