It states that only the fittest males can afford the time and energy to maintain a long tail.

The gular is dichromatic in bullfrogs, with dominant and fitter males displaying yellow gulars.

Usually a female chooses the most dominant and fit male to mate with.

As 3-D Man, Chuck Chandler possessed approximately three times the physical capabilities of an extremely physically fit but otherwise normal human male.

However, the queens often try to escape the males, allowing only the fastest and the fittest males to mate.

One is that a long tail indicates an extremely fit male: to grow such a tail and carry it around will take extra energy.

In 1910, the universal training scheme was introduced, under the scheme all medically fit males 14-18 years of age had to serve in cadets.

Since 1904 military service has been compulsory for all fit males between the ages of eighteen and forty-nine.

Examples include favoring kin in altruistic behaviors, female selection of the most fit male, and defending a territory or harem from rivals.

A discreet adulteress can get the genes of the fittest male and the investment of the most generous male.