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For example, why do peacock females choose males with the biggest tail? If there is no advantage in such tail.

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    $\begingroup$ Have you done some work looking for an answer? $\endgroup$ – Bryan Krause Dec 11 '16 at 19:07
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    $\begingroup$ Wikipedia is often helpful....Have a look at Fisherian runaway and Zaahavi's handicap and eventually just at sexual selection. $\endgroup$ – Remi.b Dec 11 '16 at 19:12
  • $\begingroup$ Sexual selection is a big topic and while I am not quite an expert in this field, I doubt anyone would be able to really make a good summary of the possible reasons leading to sexual selection. It is even more true that there are big issues of semantic in the field (see the work of Hannah Kokko). Note however that reading the wiki article on Fisherian runaway will already bring you a long way. $\endgroup$ – Remi.b Dec 11 '16 at 19:16
  • $\begingroup$ Oh You should read about the sexy son hypothesis too $\endgroup$ – Remi.b Dec 12 '16 at 15:20
  • $\begingroup$ Also you can mark an answer as accepted. $\endgroup$ – Roni Saiba Jul 14 '17 at 6:09
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There are two common explanations both are difficult to demonstrate. I personally favor the former but I will not claim it is the only explanation.

  1. selection starts as either a random occurrence or as some initially beneficial trait (a slight increase in tail length may have been beneficial originally) Then runaway selection takes over. Any increase also causes increased attraction because the evolved behavior of the desire in the females only functions as bigger is more attractive(or whatever=more attractive). This pushes further and further into absurdity becasue there is not behavioral regulation to say enough is enough. So any increase in the males increases attractiveness meaning any individual male with less can't reproduce in the current population of females no matter how beneficial to the individual male survival. Additionally no female will develop a favoring of smaller tail feathers becasue her smaller tailed offspring will not be able to find mates for the same reason. A positive feedback loop like this won't stop until it hits a point where the cost of tailfeather is more than the advantage of increased mating becasue the individual never lives long enough to mate.

  2. By carrying a handicap the organisms shows it can withstand a greater burden and thus must be better.

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  • $\begingroup$ so the desire of some trait can be transferred by genes ? $\endgroup$ – Gleb Voronchikhin Dec 11 '16 at 20:24
  • $\begingroup$ of course, most behavior is controlled by genes. The genes that control the structure of the brain control behavior. Even In humans a significant amount of our behavior is controlled by genes. $\endgroup$ – John Dec 11 '16 at 20:30
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    $\begingroup$ most behavior is controlled by genes is misleading and sounds like you might misunderstand the concept of heritability. You would at least need a reference for such claim. $\endgroup$ – Remi.b Dec 12 '16 at 15:18
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    $\begingroup$ I don't think that FIsher Runaway process (your first bullet point) necessarily require an initially beneficial trait under the sexy son hypothesis (but I am not 100% clear with all these concepts in sexual selection) $\endgroup$ – Remi.b Dec 12 '16 at 15:20
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    $\begingroup$ My main issue was that "controlled by genes" is misleading. One can tell whether a behaviour is innate or learned or whether phenotypic variance is due to environment variance or genetic variance. When saying "controlled by genes", it makes me feel that you are stating that most of the variance in behaviour is explained by genetic variance (which I think would require a reference). $\endgroup$ – Remi.b Dec 12 '16 at 17:16

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