oh Wikipedia

[gusl]

Wikipedia's article on balancing selection fails to mention the obvious example of gender in mammals! Any population-wide propensity to produce more of one gender (assuming childhood mortality doesn't preferentially affect one gender) implies reduced fitness for most fathers^*, and a Darwinian "incentive" to produce more of the other gender. But I would be afraid of this example being deleted because I don't have any sources, since it's just common sense... and [[Wikipedia isn't CommonSensePedia!]].


^{* - I say "fathers" because it is the sperm that are responsible for the child's gender.}

Comments

[the-locster.livejournal.com]

I wonder - what is the nature of the feedback mechanism? Perhaps high level psychological changes which in turn create hormonal changes?

[gustavolacerda.livejournal.com]

Interesting question!

Arguments/analyses like the one I made above sometimes assume that certain changes can be physiologically accomplished (e.g. variables like the proportion of Y-sperm are under continuous control).

Darwinian selection is sufficient to explain the "negative feedback" that leads to an even gender ratio, so I don't think that individual-level recognition of the current gender ratio is necessary (though it would be useful, especially in populations that undergo a lot of fluctuations in the gender ratio, e.g. due to war).

In a very stable equilibrium (such as the 50/50 gender example), it seems plausible that evolution found a way to hard-code this (the alternative, the continuous control theory seems implausible, since it can't be very sensitive, considering that gender ratio signals can be very biased, and such control provides no clear benefit).

[the-locster.livejournal.com]

Ahh ok, wikipedia refers to the Darwinian balancing of sex as Fisher's principle. The reason I went down that thought path was that I've heard of environmental influences and perhaps epiginetic factors (e.g. in times of stress such as limited limited food). However, many of the environmental factors listed here (http://en.wikipedia.org/wiki/Human_sex_ratio#Environmental_factors) come under the heading of the disruptive effects of modern chemicals.

[gustavolacerda.livejournal.com]

Thanks! Fisher was one smart guy!

[rdore.livejournal.com]

http://en.wikipedia.org/wiki/Wikipedia:Be_bold

[gustavolacerda.livejournal.com]

To be honest, the main reason I don't edit very much is probably the very little feedback from readers, editors or administrators. It's hard to know if you're making any difference.

Writing for and presenting in academic venues leads to a lot more feedback (and usually by qualified people), not to mention professional advancement.

[(Anonymous)]

If by gender you mean sex than your "common sense" theory is BS and you might want to have a look at http://en.wikipedia.org/wiki/Fisher%27s_principle. If not than scratch my comment.

Conny

[gustavolacerda.livejournal.com]

I already got that, thanks. This Wikipedia article confirms that Fisher's principle is very similar to what I arguing for.

FYI, in the English language, it's preferable to use "wrong" rather than BS, unless your intent is to offend.