Chapter 18 - Populations and Evolution
- Created by: mburgess
- Created on: 30-01-18 10:23
Fullscreen
Key Words:
- Gene pool - All the alleles of all the genes within a population at one time
- Allelic frequency - the number of times an allele occurs within a gene pool
- Stabilising selection - selection against the extreme phenotypes
- Directional selection - selection for one extreme phenotype
- Disruptive selection - favours individuals with extreme phenotypes rather than around the mean of the population
- Speciation - the evolution of a new species from existing ones
- Species - a group of individuals that share the same genes and can interbreed to produce fertile offspring
The Hardy-Weinberg Principle
- Provides a mathmatical equation that can be used to calculate the frequencies of the alleles of a particular gene in a population
- The principle makes the assumption that the proportion of dominant and recessive alleles of any gene in a population remains the same from one generation to the next and 5 conditions are met
- There can be no mutations
- The population is isolated
- There is no selection - all alleles have an equal chance at going to the next generation
- The population is large
- Random mating
p + q = 1.0
- p = dominatant allele
- q = recessive allele
- 1.0 as the probability of one allele plus the other is 100%
p^2 + 2pq +q^2 = 1.0
- This equation is used to express it as a probability
Variation in Phenotypes…
Comments
No comments have yet been made