Question

1. In the runaway process of sexual selection, what trait is under selection in the males and what trait is under selection in the females. Which male traits are favored, and which female traits are favored? Bonus: Why is runaway selection an example of maladaptive evolution?

Answer 1

In the runaway process of sexual selection the trait with subdued male ornamentation will be under selection in the males. And in case of females such subdued male ornamentation is under selection.

But the more exaggerated ornamentation of the males are favored along with in case of females the sexual selection of such exaggerated male ornamentation occurs.

This phenomenon can be seen because of positive feedback loop mechanism. According to Fisher The two characteristics affected by such a process, namely [ornamental] development in the male, and sexual preference for such development in the female, must thus advance together, and … will advance with ever increasing speed. It is easy to see that the speed of development will be proportional to the development already attained, which will therefore increase with time exponentially, or in a geometric progression.

A maladaptive evolution is an type of evolution where the trait is harmful for the organism rather than helpful. In case of runaway process this type of maladaptive evolution can be observed. The runaway process of sexual selection favors the exaggerated male ornamentation which is bulky and heavy for the animal. In case of male peacock this phenomenon can be observed, as in case of the colorful feathers of the peacocks than the pale feathers of the peahens. This results the birds being more colorful in the wild and can be observed from a great distance thus being more vulnerable by the predators.