BIOL 112 Lab 1

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Hardy-Weinberg Equilibrium

Individuals do not evolve—populations do

Hardy-Weinberg Equilibrium is a theoretical (i.e. not real) model because allele frequencies are held constant by 5 assumptions:

1. Large population size
2. No emigration or immigration
3. No genetic mutation
4. Random mating
5. No natural selection

Mnemonic^?: large great mute mate selection

Allele Frequencies

Percentage frequency of each allele represented by $p$ and $q$.

$p+q=1\,\!$

Genotypic Frequency

3 possible genotypes for a trait:

1. Homozygous dominant: AA ($p^{2}$)
2. Homozygous recessive: aa ($q^{2}$)
3. Heterozygous (carrier): Aa ($2pq$)

$p^{2}+2pq+q^{2}=1\,\!$

Genetic Bottleneck

Something kills a majority of individuals in a population, so only a few individuals are allowed to repopulate the species. This causes many allele variants to change frequency suddenly or be completely lost.

Similar effect is founder effect where a group of individuals breaks off to form a new population.