Natural selection Flashcards
What is natural selection?
When the allele codes for a characteristic that increases the chances of an organism surviving, its frequency within a population increases
What causes mutations?
Randomly occurring
What can randomly-occurring mutations cause?
Result in a new allele being formed which may be beneficial to the organism
Due to mutations, there may be differential reproductive success. What does this mean?
Individuals that have an allele that increases their chance of survival are more likely to survive, reproduce and pass on their genes and beneficial allele, than individuals with the less advantageous alleles
Outline the process of natural selection.
1) a random mutation causes some members of the population to have a beneficial allele which increases their chance of survival
2) they then are more likely to reproduce and pass on their advantageous alleles to their offspring
3) the greater proportion of the next generation inherits the beneficial allele
4) Then the offspring are more likely to survive and pass on their advantageous alleles
5) The frequency of the beneficial allele increases from generation to generation
6) Over generations this leads to evolution as the advantageous alleles become more common in the populations
What is evolution?
Gradual change in species over time
What is an adaptation?
A feature that helps organisms to survive in their environment
What are the three types of adaptations?
Behavioural
Physiological
Anatomical
What are behavioural adaptations?
The way an organism acts that increase it’s chances of survival
What are physiological adaptations?
Processes inside an organism’s body which increase its chances of survival
What are anatomical adaptations?
Structural features of an organisms body that increase its chance of survival
