1. Genetic Equilibrium
Population genetics looks at evolution at the genetic level
Types of Evolution:
Convergent Evolution
Different species evolve similar traits
Analogous structures – same function, look different
Divergent Evolution
- 1 species changes into 2 different species, each fitting into different niches of the environment
- Causes adaptive radiation – filling a void in an environment… usually food
Coevolution
- Two unrelated species evolve adaptations to each other’s influences

2. Genetic Equilibrium
In a population, there are different variations for genes, which is called the gene pool
The allele frequency is how often a dominant or recessive allele shows up in an organism’s genotype
The phenotype frequency is how often a trait is expressed
Hardy-Weinberg Equilibrium
Genotype frequencies tend to remain the same through generations, unless it is changing through evolution
Shows that populations are at equilibrium most of the time

3. Disruptions to Genetic Equilibrium
Any change to the genetic equilibrium of a population results in evolution
Disruption to Genetic Equilibrium:
Mutations
Radiation or chemicals can cause changes in the DNA sequence, causing new alleles to be created
Beneficial mutations are a vital part of evolution
Gene Flow
Genes move from one population to another
Ex: Immigration & emigration; seed dispersal
New alleles are introduced into populations

4. Disruptions to Genetic Equilibrium
Genetic Drift
Allele frequencies change randomly or as a result of chance
Founder effect: newly populated areas have less diversity
Non-random mating
Mating is often influenced by location; related individuals can mate
Also caused by organisms selecting traits similar to theirs
Traits can become amplified in populations
Natural Selection
Favorable traits are selected for and persist in a population