The article explores how male and female animal adaptations affect fertilization when females mate with multiple males. Females can choose which male fathers their offspring based on various traits like courtship and sperm characteristics. This can lead to competition where males try to ensure their sperm is the one fertilizing eggs. Male and female reproductive parts, like genitalia, have evolved to balance competing interests. The research shows that sexual conflict often arises during mating and fertilization due to differences in male and female reproductive goals. Understanding these post-copulatory interactions sheds light on the complex relationships between males and females in the animal kingdom.