Hardy-Weinberg equation

what does the Hardy-Weinberg principle state

it states that in a stable population, frequency of alleles would stay constant generation after generation

but certain conditions hv to be met in order for this to happen

in the Hardy-Weinberg equation, what does p & q denote

p & q denote the 2 allele frequencies

p = dominant allele

q = recessive allele

since p & q represent 100% of the alleles of a specific gene in a gene pool, p + q = 1

what does p² + 2pq + q² mean

this allows us to calculate or predict the genotype frequencies

p² = frequency of individuals homozygous for one allele

2pq = frequency of heterozygous individuals

q² = frequency of individuals homozygous for one allele

if one of the genotype frequencies is known, allele frequency can be calculated using the same equations

what’re some conditions that allow the Hardy-Weinberg equilibrium to stand true

• no mutations (cuz mutations introduce new alleles, which’ll disrupt the stability)

• there’s random mating (in most species, non-random species is the norm, which leads to sexual selection, which leads to non-equilibrium)

• natural selection shouldn’t occur

• no genes should enter or leave population

  • loss of genetic diversity (which results from genes leaving population) ruins the equilibrium

  • breeding between two populations also results in the introduction of new alleles

• population must be large (genetic drift or chance events may change allele frequency, which affects small populations the most)

in artificial selection, what does selecting certain traits over others, lead to?

it leads to a change in the allele frequency

causes a directional selection towards one specific trait, leading to changes in gene pool allele frequencies

just a note - unintended consequences of human action (such as an insect becoming immune to pesticides, or the evolution of resistance in bacteria when an antibody is used) isnt artificial selection but instead natural selection