Final answer:
Sexual selection refers to the selection pressures males and females experience to obtain mates, resulting in the development of secondary sexual characteristics. It arises when one sex has more variance in reproductive success than the other, leading to distinct phenotypic differences between males and females.
Step-by-step explanation:
Sexual selection refers to the selection pressures males and females experience to obtain mates, resulting in the development of secondary sexual characteristics that do not directly benefit survival but maximize reproductive success. Male birds with colorful plumage compared to females of the same species are an example of this.
A more accurate definition of sexual selection is that it arises when one sex has more variance in reproductive success than the other, leading to distinct phenotypic differences or sexual dimorphisms between males and females. This can be due to male-male competition for mates or female choice based on certain traits.