110 likes | 475 Views
Types of Natural Selection Notes. February 19, 2013. Types of Natural Selection. Stabilizing Selection 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
E N D
Types of Natural Selection Notes February 19, 2013
Types of Natural Selection • Stabilizing Selection • Occurs when natural selection works against the 2 extremes of a trait to make the population more uniform
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 • Directional Selection • 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 • Disruptive Selection • Selects against the mean of the population
Disruptive Selection Example • If there are 2 types of foodto 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.