Types of
Selection
Types of Selection
●Directional
●Stabilizing
●Disruptive
●Sexual
●Artificial
Directional Selection
●One extreme of a trait is selected for, rather
than the average
●Individuals with that extreme trait are more
successful
●Examples?
Directional Selection - Examples
●Peppered Moths
●Pocket Mouse
Stabilizing Selection
●Individuals with the average trait are
selected for, rather than either extreme
●Individuals with the average trait are more
successful
●Examples?
Stabilizing Selection - Examples
●Human baby weight
●Lizard tail length
Disruptive Selection
●Individuals at both extreme ends are
selected for, rather than the average
●Individuals with either extreme trait are more
successful
●Examples?
Disruptive Selection - Examples
●Rabbit fur color
●Swallowtail
butterfly pattern
Recap: Types of Selection
Sexual Selection (nonrandom mating)
●Mates are picked based on traits, not at
randomly
○ Size
○ Strength
○ Coloration
○ Ability to provide
○ Many more
●Examples?
Artificial Selection (selective breeding)
●People, rather than nature, choose
desireable traits in organisms, and breed
individuals together based on those
●May act in opposition to nature
●Examples?
Artificial Selection (selective breeding)