Selection Flashcards
What is selection?
The process which organisms that are better adapted to their environment tend to survive & breed.
What are the two types of selection?
- Directional
- Stabilising
What is directional selection?
When environmental conditions may favour individuals that vary in one direction from the mean of the population.
What does directional selection do to the characteristics of a population?
It changes them.
What is stabilising selection?
When environmental conditions favour average individuals.
What does stabilising selection do to the characteristics of a population?
Preserves them.
What are polygenes?
When multiple genes have a combined effect on the phenotype.
What phenotypes mean that the organisms is more likely to survive environmental change?
Phenotypes that are best suited to the new conditions.
If the environmental conditions remain stable, which phenotypes are favoured?
Phenotypes closest to the mean
(Extremes are selected against)
If the environmental conditions change, which phenotypes are favoured?
Phenotypes at one extreme of the population is selected for.
(The other extreme is selected against)
(The mean shifts)
