Population Genetics - Genetic Drift

The allele frequency after reproduction $p^{'}$ is not konwn exactly.
Fluctuation of genotype frequencies depends on population size - it will be much more variable in smallerpopulations and not match Hardy-Weinberg Equilibrium as much.

Binomial Distribution

Wikipedia
The probability of receiving a certain number of copies of one allele in a new generation is given by the Binomial Distribution:

Var {p} = \frac{p q}{2 N}

Smaller $N$ means larger variation, meaning genetic drift is stronger in small populations. In small populations, alleles are more likely to be purged or become fixed compared to a larger one.
These are the equilibrium points ( $p = 0$ and $p = 1$ )
Probability of fixation of a new mutation: $p = 1 / 2 N$
Expected time to fixation is directly proportional to $N$ and inversely proportional to $p$ .
- For a new mutation, time to fixation is around $4 N$ ? Units?

Heterozygote frequency $H$ at time $t$ is given by:

H_{t} = H_{0} {(1 - \frac{1}{2 N})}^{t}

Meaning that heterozygosity changes by $Δ H = - \frac{1}{2 N}$ each generation.

A genetic bottleneck event can have long lasting effects on health of concerned population.

Leads to random fixation of alleles at a locus
Because of fixation, genetic drift results in less heterozygosity, meaning genetic diversity will erode over time
INcreases the variance in allele frequencies between populations, meaning populations will become more genetically different from each other (assuming no Population Genetics - Migration)