Selection Flashcards
What four things do Normal distribution curves have?
No bias
Bell shaped curve
Symmetrical curve
Data surrounds a central point
What are polygenes?
Most characteristics are a result of multiple genes
What are polygenes affected by?
The environment
What does a change in the environment =?
Changes in the environment = changes in the mean
What is the mode?
The most common result
What is the mean?
Average
What is the median?
The middle value
What does directional selection favour?
Favours the extreme characteristic
What happens to cause directional selection?
There is an environmental change, which changes the phenotype that is most needed. So the normal distribution curve changes direction. Change in the mean characteristic occurs
What does stabilising selection favour?
Selection acts against both extremes in a range of phenotypes. Favours the most common
What are the outcomes of stabilising selection?
Phenotype variation is reduced because the environment has remained stable
