Variation & Evolution
- Created by: beth-marie2511
- Created on: 16-06-16 22:19
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- Variation & Evolution
- Population Genetics
- Allele frequency = Frequency of alleles within a genepool
- Gene pool remains stable if the environment remains stable
- If the environment changes some phenotypes will have a selective advantage
- Some will have a selective disadvantage.
- The frequency of these alleles will decrease
- This will cause a change in allele frequency
- The frequency of these alleles will increase
- Some will have a selective disadvantage.
- Selection pressures have an effect on the frequency of alleles
- Open population = overlapping populations (immigration of alleles)
- Closed population = barriers between populations
- Why would a gene pool change?
- Mutation
- Genetic Drift
- A random change in the frequency of an allele in a population/ gene pool
- The alleles in the offspring are a sample of those in the parents
- There is an element of chance in determining whether any given individual survives and reproduces
- Can cause alleles to completely disappear from a population and therefore reduces genetic variation
- E.G Darwin's Finches
- They were geographically isolated on different islands and had to adapt to the food supplies and the new environment
- Formed from a common ancestor
- Adaptive Radiation
- Disasters that result in the loss of a section of a population
- Natural selection - loss of genes because individuals are unable to compete / survive and breed
- Population Genetics
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