Types of selection Flashcards
What is the selection process?
Selection is the process in which organisms that are better adapted to their environment tend to survive and breed.
What is directional selection?
Where selection may favour individuals that vary in one extreme direction from the mean of the population.
This is called directional selection and changes the characteristics of the population.
What happens in a directional selection?
- When the environment condition change, the phenotype (the physical and biochemical characteristics of an organism) that are suited for the new conditions are more likely to survive.
- Some individuals, which falls either the left or right of the mean.
- The offspring will possess alleles from those individuals and over time the mean will then move in the direction of these individuals.
What is stabilizing selection?
Where the population mean will move more towards average.
It happens when the environment is not changing, reducing the possibility of a range of possible characteristics.
What is disruptive selection?
Where the population will have 2 extremes that have large groups and less in the average.
What are the 3 types of adaptations?
1) Anatomical - Structural features which increase an organism’s chance to survive and reproduce e.g. shorter ears and thicker fur in arctic foxes compared to foxes in warmer climates.
2) Physiological - Processes inside of organisms body that increase its chances of survival and reproduction. e.g. oxidising fat rather than carbohydrate in kangaroo rats to produce extra water in dry desert climates.
3) Behavioural - These are acts which an organism does to increase its chances of survival and reproduction e.g. autumn migration of swallows from the UK to Africa to avoid food shortage in the UK winter.
What does a genetic bottleneck do?
It reduces genetic diversity, the reduction of different alleles in a gene pool reduces genetic diversity.
