evolutionary biology

sexual selection

what is sexual selection?

a type of natural selection that occurs when individuals differ in their ability to obtain mates and reproduce successfully

what is the main idea of sexual selection

some traits increase an individual’s chances of finding a mate, even if those traits don’t necessarily improve survival

two types of sexual selection

1. intrasexual selection

2. intersexual selection

what is intrasexual selection

competition within a sex

• individuals of the same sex compete with one another for access to mates

what are examples of intrasexual selection

• male deer competing using their antlers

• male elephant seals competing for access to females

• male birds competing for territories

what is intersexual selection

mate choice

• one sex chooses mates based on particular characteristics or behaviors

• one sex chooses individuals of the opposite sex

examples of intersexual selection

• female peacocks preferring males with elaborate tails

• female birds choosing males with attractive songs

• females selecting males based on courtship displays

sexual dimorphism

the physical differences between males and females of the same species

examples of sexual dimorphism

• differences in body size

• differences in coloration

• differences in ornaments —> antlers or elaborate feathers

how is sexual dimorphism influences by sexual selection