Peahens prefer to mate with peacocks that have the brightest and largest tail displays. the peacock’s tail is a disadvantage to the males, because it is large and cumbersome and hinders them from escaping from predators. given these facts, why isn’t the peacock’s tail selected against by natural selection?

Peacock with larger tails are most likely to produce more progeny.

Explanation:

Sexual selection is a type of natural selection wherein individuals with some specific genetic traits are preferred as a mate for interbreeding by the individuals of the opposite gender of the same species. For instance, in some species, males with large size have a greater chance to mate and pass on their genes to the progeny. This results in an increased frequency of the genes for the larger body size in population over time. Therefore, sexual selection results in the reproductive advantage for some individuals over others of the same species and sex.

In the given example, a peacock with larger tails is preferred as a mate by peahens and is able to produce more offspring. Due to its reproductive advantage, larger tails in peacocks are not selected against by natural selection.  

the glands which are associated with each description is given below: