Let’s go to The Origin of Species (pp. 56 & 57 of my edition)”:
quote: ... Thus it is rendered possible for the two sexes to be modified through natural selection in relation to different habits of life, as is sometimes the case; of for one sex to me modified in relation to the other sex, as commonly occurs. ...
I could argue that he is talking about a subset of natural selection, but it doesn't matter that much to me.
quote: ... sexual selection. This form of selection depends, not on a struggle for existence in relation to other organic beings or to the external conditions, but on the struggle between the individuals of one sex, generally the males, for the possession of the other sex. The result is not death to the unsuccessful competitor, but few or no offspring. ...
You don't have this in your scenario, so by the definition that you refer to there was no sexual selection.
Thus the changes in hereditary traits is not due to sexual selection .... take a guess?
Let me add that several of the couples would have lost the first zygotes (happens all the time) and some may even have had miscarriages. These are instances of natural selection operating on non-viable genetic combinations. Those genetic combinations are not represented in the new generation due to selection.
The distinction made by Darwin (above) is that what is referred to as sexual selection is an additional mechanism within the overall natural selection process which differs from sexual reproduction in species where no such selection takes place. Thus no matter how you cut it natural selection involves mating and reproduction and the subsequent changes to hereditary traits in the population
Nah. My scenario is entirely possible, if not probable.
Not really. Your scenario neglected the entirely realistic point that good looking people would get laid more often than than the ugly ones. The ugly ones might get it sometimes, but not as often as the attractive ones. You essentially neglect that one attractive male, might date the entire cheerleader team because he can, and that one attractive female might date the entire football team. And, if we are talking about reproductive acts - there will be more attractive people born than unattractive people.
Which would be sexual selection for attractive traits - one attractive member manages to either impregnate or get pregnant multiple partners as opposed to only one partner, or no partners at all.
If it turns out that ugly people have as many children as attractive ones, but with fewer partners, then there would be no sexual selection. Individuals would still be selecting partners, but that isn't sexual selection (the biological term), that's just individuals trying to find 1 or more available mates.
The distinction made by Darwin (above) is that what is referred to as sexual selection is an additional mechanism within the overall natural selection process...
I don't think so, RAZD. Darwin makes this key distinction at the end of his quote (which you have conveniently deleted, btw):
quote:... Sexual selection is, therefore, less rigorous than natural selection.
Why would Darwin say this if sexual selection and NS were the same thing?
And one more question: If, as you say, sexual selection is "an additional mechanism within the overall natural selection process," then do you also include mutation, random genetic drift, and gene flow as said same "addition mechanisms" of NS?
Natural Selection ” its power compared with man's selection ” its power on characters of trifling importance ” its power at all ages and on both sexes ” Sexual Selection ” On the generality of intercrosses between individuals of the same species ” Circumstances favourable and unfavourable to Natural Selection, ...
That's the table of contents, and sexual selection is in the chapter on natural selection ... that looks like he regards it as a part of natural selection.
It is also generally accepted in the modern biological evolution that sexual selection is a part of natural selection. Natural selection would be a compendium of selection mechanisms that differentiate one organism from another.
... then do you also include mutation, random genetic drift, and gene flow as said same "addition mechanisms" of NS?
Part of evolutionary biology yes, part of a selection process no.
But I also don't lose sleep over it. One just needs to be specific when they talk of such things in order to be clear in the presentation of ideas.
Still doesn't say different, that is your issue eh? The whole chapter is on Natural Selection, part of it is on sexual selection, because sexual selection is a - less rigorous - subset of natural selection.
The trapezoidal rule is a less rigorous way to approximate area under a curve than the simpson rule, but both are ways to approximate area under a curve.
Take away that one sentence and see if he compares natural selection to sexual selection before coming to that conclusion.
It's sex, but it's not selection if individuals aren't being selective. And that's exactly the situation you've described - a situation where sexual selection is completely absent because individuals aren't being selective about mate choice. They're simply mating with whoever is available.
You and all the other bad-looking boys wanted to go out with Judy, the popular and good-looking cheerleader. But only Tommy, the popular and good-looking football player, got to go out with her. Meanwhile, you and your bad-looking buddies, who were too chicken to go out for football, had to be satisfied with the uglier girls.
Except that we weren't satisfied; all the ugly girls were after Tommy, too. They ignored us nerds.
That's sexual selection. Tommy was the preferred mate for all the girls; thus, he had his choice of the best adapted. The rest of us were denied mate access because we were inferior. Of course, Tommy wound up getting the prom queen pregnant, and now he lives with her in a trailer down by the railroad tracks, with their seven children.
See? His greater mate access directly results in greater reproductive success. Me, who didn't get laid until the age of 20, has no children at all. My restricted mate access leads to reduced reproductive success. (As well as more free time.)
Sexual selection is a form of natural selection. It's right there in the name - "selection."
Nevertheless, everybody got dates for the Prom”even you with your pimples and pigeon chest.
Then there's no selection. There may be sex, but there's no selection if people aren't being selective about mate choice. If people are mating at random, with the first available mate, no sexual selection is present.
You still haven't presented an example of sexual selection that doesn't result in natural selection. If sexual selection wasn't selective, well we'd change the name for one thing, but additionally, it couldn't be associated with any morphological change.
Yet, peacock males do have bright plumage, and male rams did evolve natural weapons for non-lethal competition; thus, we know that sexual selection is a form of natural selection. It certainly wasn't predation that resulted in peacock plumage, now was it?
Out here in this Navy shipyard town the ugly ones seem to be doing all right.
More or less effectively than the handsome guys?
C'mon, be honest. Even prostitution is a form of selective sexual access; you have to pay - and therefore be able to pay - to play; that's akin to the hen forcing prospective mates to build her a nest.
Sexual selection isn't just sex - it's about being choosy. You keep presenting examples where people aren't being choosy at all, so how can that be sexual selection if no one is selecting the best mate?
Even prostitution is a form of selective sexual access; you have to pay - and therefore be able to pay - to play; that's akin to the hen forcing prospective mates to build her a nest.
Prostitutions a pretty complex behaviour to fit into a simple approach to sexual selection, as well as the trade aspect there is also the fact that prostitutes normally try their damnedest to prevent their clients having reproductive success.
So while you might need money to hook up with a prostitute you might have more reproductive success using the money to get a woman drunk in a bar.
Of course many of these are such complex social behaviours that they may reflect nothing genetic. In this case once again you might have 'selection', in terms of mate choice strategies, but not sexual selection in evolutionary terms as there is no hereditary trait which will continue to be selected.
Prostitutions a pretty complex behaviour to fit into a simple approach to sexual selection, as well as the trade aspect there is also the fact that prostitutes normally try their damnedest to prevent their clients having reproductive success.
It is, nonetheless, an example of people being choosy about mates, which was all I intended it to be. Really, the instructive value of just about any example involving human beings is likely to be limited.
He doesn't say it is different just less rigorous.
I don't see anything there that is synonymous with different. This would be consistent with something that is part of something else.
Let's return to Darwin's actual quote:
quote:...Sexual selection is, therefore, less rigorous than natural selection.
He doesn't say "less rigorus form of natural selection,: he says "less rigorous than natural selection." "Than" implies difference. Darwin clearly saw sexual selection and NS as two different things. He was interested in how "rigorous" sexual selection was when compared to that of NS, which he understood to be a matter of fecundity, not just a matter of mating success.
Natural Selection ” its power compared with man's selection ” its power on characters of trifling importance ” its power at all ages and on both sexes ” Sexual Selection ” On the generality of intercrosses between individuals of the same species ” Circumstances favourable and unfavourable to Natural Selection, ...
The chapter is not titled "Selection" but "Natural Selection" ...
... and it is still rather silly to argue about this when modern biological evolution regards sexual selection as part of natural selection (selection mechanisms that occur naturally).
quote:It is also useful to make a mechanistic distinction between ecological selection and the narrower term sexual selection. Ecological selection covers any mechanism of selection as a result of the environment (including relatives, e.g. kin selection, and conspecifics, e.g. competition, infanticide), while sexual selection refers specifically to competition between conspecifics for mates.[9]
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