4.4 GENETIC DIVERSITY & ADAPTATIONS Flashcards
What is genetic diversity?
The number of different alleles in a population.
What is the definition of population?
A group of individuals of the same species that live in the same place and can interbreed.
How do you increase the genetic diversity?
The more variety of alleles.
What is evolution?
The frequency of alleles in a gene pool changes over time, as a result of natural selection.
What is a niche?
A species’ role in the environment, where species in the same niche will compete,
What is natural selection?
Species better adapted survive and pass on their alleles, whereas those that aren’t die out.
What are the principles of natural selection? (new alleles)
- Random mutations result in new alleles of a gene.
- Advantageous alleles lead to reproductive success.
- This advantageous allele is inherited and passed through generations.
- As a result, the allelic frequency changes in a population - affecting the gene pool and leading to evolution.
How does natural selection work with old alleles?
- Already lots of different alleles & phenotypes.
- Environmental changes create selection pressures.
- This cause only the advantageous alleles to survive and be passed on.
How are organisms adapted to their environment and niches?
- Behaviorally
- Physiologically
- Anatomically
What is directional selection?
- Favors an extreme phenotype.
- Shifts the normal distribution curve towards one of the extreme ends.
In what environment does directional selection occur?
In a changing environment.
How does direction selection affect the mode and variation?
- Reduces variation and SD.
- Shifts the mean/mode left or right.
What is stabilizing selection?
- Favors the average values (selects against the extremes)
- Shifts the normal distribution curve towards the centre.
In what environment does stabilizing selection occur?
In a stable, unchanging environment
How does stabilizing selection affect the mode and variation?
- Reduces variation
- Has no effect on the mean/mode.
