Natural selection was Darwin’s brilliant hypothesis, independently conceived by Wallace, that accounts for adaptations, features that appear “designed” to fit organisms to their environment.

TLS Online TPP Program

#Id: 9416

#Unit 11. Evolution and Behavior

A trait can evolve by sexual selection if it increases a male’s overall fitness, even if it decreases survival.

Exaggerated secondary sexual traits are favored by sexual selection because they increase male mating success.

TLS Online TPP Program

#Id: 9417

#Unit 11. Evolution and Behavior

The second part of Darwin’s hypothesis is that exaggerated secondary sexual traits decrease survival.

TLS Online TPP Program

#Id: 9418

#Unit 11. Evolution and Behavior

Selection favors mating displays that maximize a male’s lifetime fitness.

TLS Online TPP Program

#Id: 9419

#Unit 11. Evolution and Behavior

Intersexual selection - Members of one sex, usually females, choose mates based on attractive characteristics such as color of plumage or sound of courtship song.

TLS Online TPP Program

#Id: 9420

#Unit 11. Evolution and Behavior

Runaway selection: Females choose mates without the offering of obvious material benefits or parenting skills, and instead make their choices based on plumage color or courtship peahen may choose her peacock with long tail feather.

TLS Online TPP Program

#Id: 9421

#Unit 11. Evolution and Behavior

Handicap principle: Long tail feathers function as a sign of an individual’s genetic quality because the bearer must be able to afford this energetically costly trait.