Types of Natural Selection Notes

April 22, 2023

Types of Natural Selection

A. Stabilizing Selection1. Occurs when natural selection works against the

2 extremes of a trait to make the population more uniform

Stabilizing Selection

Stabilizing Selection Example

• Birth weight of babies– Babies that are too big or too small might have

less chance of being born healthy.

Natural Selection

B. Directional Selection1. Selects the extreme of 1 trait

Directional Selection Example

• In a population of plants, flowers with the brightest color might be selected for in order to attract the most pollinators.

Natural Selection

C. Disruptive Selection1. Selects against the mean of the population

Disruptive Selection Example• If there are 2 types of food to eat for a population

of birds, either of 2 different beak shapes (sharp or blunt) might be selected for, but a beak that’s the average of the 2 shapes might not be particularly good at eating either prey, so it would be selected against.