In many websites/books they are referred to as part of the same process whereby:

  • "runaway" describing that the process continues even after traits become maladaptive
  • the "sexy son theory" explains the mechanism that underlies this.

However many sites (like wikipedia) describe them as two alternative processes.

What am I missing?


The Fisherian runaway is the observed phenomenon of an "arms race" of features and traits in sexual dimorphism, the Sexy sons hypothesis is the theory of why it happens. One is factual/known data and the other is a hypothetical explanation as to why we see that data.

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    $\begingroup$ It is necessary to emphasise the role of female directional selection observed in the Fisherian runaway. Koinophilic peahens will select the most ornamental peacocks - it is an arms race of sexual characteristics, even if maladapted to the environment. The Sexy Sons hypothesis is not purely a descriptor of why it arises - it demonstrates that females select males with the probability of ornamental sons capable of widely spreading the mother's genes. The Fisherian runaway could be effected by a non-(Sexy Son) origin. $\endgroup$ – Epistemonaut Apr 19 '18 at 15:47
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    $\begingroup$ @epistemonaut- thanks for your response. Please could you give me an example of how runaway selection could arise in the absence of the sexy son mechansim. As I am still unable to understand how this is possible. $\endgroup$ – Ganon Apr 20 '18 at 0:09

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