Sexual Selection
... Intersexual selection… Female Choice
Females may select for males
with traits that indicate their quality
...
Sexual coercion
Sexual coercion in animals is the use of violence, threats, harassment, and other tactics by males to help them forcefully copulate. Such behavior has been compared to sexual assault, including rape, among humans.In nature, males and females usually differ in reproductive fitness optima. Males generally prefer to maximize their number of offspring, and therefore their number of mates; females, on the other hand, tend to care more for their offspring and have fewer mates. Because of this, there are generally more males available to mate at a given time, making females a limited resource. This leads males to evolve aggressive mating behaviors which can help them acquire mates.Sexual coercion has been observed in many species, including mammals, birds, insects, and fish. While sexual coercion does help increase male fitness, it is very often costly to females. However, in spite of these costs, a possible benefit to the females is a chance to test the stamina of the males, so that only those with ""good genes"" will father their offspring. Sexual coercion has been observed to have consequences, such as intersexual coevolution, speciation, and sexual dimorphism.