Selection (distribution Curves) Flashcards
What do normal distribution curves have?
No bias
Data surrounds a central point
Curve is symmetrical
Curve is a bell shape
What is the mode?
Most common result
What is the mean?
The average
What is the median?
The middle value, when put in order lowest to highest
What are polygenes?
Characteristics as a result of multiple genes
What are polygenes affected by?
The environment
What is directional selection?
Environmental change changes the phenotype selected for
Normal distribution curve changes direction
Change in the mean characteristic occurs
What does directional selection favour?
The extreme characteristic
What does stabilising selection act against?
Both extremes in a range of phenotypes
What is the outcome of stabilising selection?
Phenotypic variation is reduced because the environment has remained stable
