Final answer:
Traits typical of a sex not directly related to reproduction are called secondary sexual characteristics. These traits aid in sexual selection and differentiate the sexes without being part of the reproductive organs.
Step-by-step explanation:
Traits which are typical of a sex but not directly concerned with reproduction are called secondary sexual characteristics. These include physical signs of sexual maturation that do not directly involve the sex organs. For example, in humans, male facial hair and female breasts are considered secondary sexual characteristics because they distinguish between the sexes but are not part of the reproductive system. Other species exhibit similar traits that result from sexual selection, such as the peacock's bright plumage, which is used to attract mates.
While primary sex characteristics are directly related to the reproductive system, secondary sexual characteristics often arise from sex steroid hormones and play supporting roles in reproductive function. They can also influence sexual dimorphism, the differences in physical characteristics between males and females of the same species that go beyond the sex organs. These characteristics can be the basis for intersexual selection, where mate choice is based on these traits, or intrasexual selection, which involves competition among members of the same sex.