Flashcards in Hardy-Weinberg Equilibrium Deck (9)
What are the assumptions of the HWE?
- mutations can be ignored
- migration is negligible (no gene flow)
- mating is random
- no selective pressure
- large population size
- equal allele frequencies in each sex
What is the underlying principle of the HWE?
p + q = 1,
where p = dominant allele frequency
and q = recessive allele frequency
What is gene flow and give an example?
- new alleles give rise to increased mutations
- new alleles introduced my migration/intermarriage
- new gene frequency
e.g. Vikings populating Ireland/Scotland
Name two types of non-random mating?
Assortative mating; partners with shared characteristics
Consanguinity; mating between close blood relatives
What happens as a result of negative natural selection?
- decreased fitness
- decreased trait prevalence
- decreased alleles
What happens as a result of positive natural selection?
- increased fitness
- increased trait prevalence
- increased heterozygote advantage
What is heterozygote advantage?
carrying the gene for a certain recessive condition can give rise to resistance on another condition
e.g. sickle cell anaemia = malaria resistance in tropical Africa
cystic fibrosis = cholera/typhoid resistance in western Europe
What is genetic drift?
statistical drift of gene frequencies due to random events (beetles by the pond)