9.4 Types of Selection Flashcards
What is selection
The process by which organisms that are better adapted to their environment tend to survive and breed, while those that are less well adapted tend not to
What organisms are subject to selection
Every organism
What causes different characteristics of a population to be present
Different environmental conditions
What is directional selection
Selection favouring individuals in one direction from the mean. This changes the characteristics of a population
What is stabilising selection
Selection favouring individuals around the mean of a population. This preserve characteristics of a population
What does direction selection result in
Phenotypes of one extreme of the population being selected for and those at the other extremes being selected against
What does stabilising selection result in
Phenotypes around the mean of a population being selected for and those at both extermes being selected against
What are the 3 types of adaptations that can occur
- Anatomical
- Physiological
- Behavioural
What is an example of an anatomical adaptation
Shorter ears or thicker hair in arctic foxes compared to foxes in warmer climates
What is an example of a physiological adaptation
Oxidising fat rather than carbohydrates to provide much needed water for kangaroos living in desert climates
What is an example of a behavioural adaptation
Swallows travelling to Africa from the UK to avoid UK food shortages in winter
