- A Sexual selection and natural selection are sometimes considered largely identical processes, despite sexual selection specifically arising from mate competition rather than differential survival alone
- B Sexual selection: differential reproductive success due to mate competition; two mechanisms: intrasexual selection (same-sex competition) and intersexual selection (mate choice by opposite sex)
- C Sexual selection is sometimes thought to operate mainly within mammalian species, rarely documented in birds or fish, despite extensively documented cases in peacocks, guppies, and stag beetles
- D Intrasexual selection is sometimes thought to specifically involve mate choice by the opposite sex, an inversion of actual terminology, since intersexual selection describes mate choice according to conventional understanding
Correct answer: B. Sexual selection: differential reproductive success due to mate competition; two mechanisms: intrasexual selection (same-sex competition) and intersexual selection (mate choice by opposite sex)
Explanation: Sexual selection (Darwin): traits increase mating success even if they reduce survival. (1) Intrasexual (male-male competition): traits for combat/intimidation - deer antlers, elephant seal mass, gorilla canines; larger sex wins mates. (2) Intersexual (mate choice): females typically choose; male ornaments evolve through: Fisherian runaway (self-reinforcing preference), good genes/handicap principle (costly ornament signals genetic quality), sensory bias. Examples: peacock tail, bird of paradise plumage, frog calls.
Concept context
Origin of life, Darwin's theory, natural selection, speciation, and evidence for evolution.