1. Population Genetics

2. Genes in a Population
Population genetics is the study of allele behavior in a population.
A population is a group of local interbreeding individuals of a single species
Example: ABO blood type
- as individuals - we carry only two alleles
- have one blood type
- as a population - we have three alleles
- have four blood types

3. Features of a population
- share a common gene pool
- described by their allele frequency
- genetically more diverse than that of an individual
  - individuals are subsets of the populations gene pool
- offspring carry the gene pool to the next generation

4. Gene Pool
All of the allele’s in population’s genes

5. Allele frequency The percentage of any specific allele in a gene pool
Genetic Equilibrium- a population in which the frequency of alleles remains the same over generations.

6. Changes in genetic equilibrium
A population in genetic equilibrium is not evolving. Both alleles and phenotypes remain the same.
Any factor that affects the genes in the gene pool can change allelic frequencies and shift the genetic equilibrium

7. Why does allele frequency change?

8. 5 Factors affecting Gene Pools
Non-random mating
Gene Flow: immigration and emigration
(The flow of genes entering or leaving a population)
Mutations

9. 4. Genetic drift: changes in allelic frequency by chance events
(Small populations because of reproductive isolation or geographic barriers)
5. Natural Selection: acting on phenotype variations