Populations - AL only (3.7.2)

The Hardy–Weinberg principle is a mathematical model used to calculate allele and genotype frequencies in a stable, non-evolving population. It assumes:

• No mutations (no new alleles)
• Large population (to reduce genetic drift)
• Random mating
• No selection
• No gene flow (no migration in or out)

To calculate allele frequencies:

Where:

• = frequency of dominant allele
• = frequency of recessive allele

To calculate genotype frequencies:

Where:

• = frequency of homozygous dominant genotype (AA)
• = frequency of heterozygous genotype (Aa)
• = frequency of homozygous recessive (aa)

A population is a group of organisms of the same species that occupy a particular space at the same time. These organisms are commonly able to interbreed.

A species exists as one or more populations.

The gene pool is all the alleles of all genes present in a population at a given time.
Allele frequency is the proportion of a particular allele in the gene pool.

These concepts are used to study genetic variation and evolution within populations.