Hardy Weinberg Equilibrium Flashcards
What is Hardy Weinberg Equilibrium?
In a large randomly mating population, gene and genotype frequencies will remain constant from generation to generation in the absence of mutation, migration, selection, genetic drift, and recombination
What is the formula for allelic frequencies?
p+q=1
What is the formula for phenotypic frequencies?
p^2 + 2pq + q^2 = 1
What major evolutionary mechanisms are in Hardy Weinberg Equilibrium? (ones that cant exist for equilibrium to be true)
Genetic drift, natural selection, mutation, migration
What can testing for Hardy Weinberg Equilibrium be used to assess?
whether a population is evolving
If a population is not in Hardy Weinberg equilibrium…
It can be concluded that the population is evolving
A population that is not evolving shows…
allele and genotypic frequencies that are in Hardy Weinberg equilibrium
What is a population?
A group of individuals within a species that is capable of interbreeding and producing fertile offspring
According to the Hardy Weinberg principle, how do alleles and genotypes change generation to generation?
remain constant in a population
What happens to allele frequencies when, in a population, gametes contribute to the next generation randomly?
frequencies will not change
What do alleles and frequencies follow? (in terms of equilibrium)?
the transmission rules of Mendelian inheritance, which maintains a constant proportions in populations across generations
What should patterns of inheritance always be in in the absence of change?
Hardy Weinberg Equilibrium
What are the requirements of Hardy Weinberg?
large population size, random mating, no mutations, no natural selection, no migration
What are the requirements of evolution?
genetic drift, inbreeding and other, mutations, natural selection, migration
What is genetic drift?
a random change in the frequencies of a population
Is Hardy Weinberg Theorem something that can actually happen?
no it is hypothetical
What is Hardy Weinberg Theorem?
in a non-evolving population, frequency of alleles and genotypes remain constant over generations
What is recombination?
sex occurs and eggs are fertilized by sperm
How is the Hardy Weinberg equation written for one locus three alleles?
(p + q + r)^2 = p^2 + q^2 + r^2 + 2pq +2pr +2qr
How is the Hardy Weinberg equation written for one locus n # alleles?
(p1 + p2 + p3 + p4 … … + pn)^2 = p1^2 + p2^2 + p3^2 + p4^2 … … + pn^2 +2p1p2 + 2p1p3 + 2p2p3 +2p1p4 + 2p1p5 + … … +2P(n-1)Pn
How is the Hardy Weinberg equation written for a polyploid?
(p+q)^c ; c = number of chromosomes
If multiple loci (genes) encode for a trait…
each locus follows the Hardy Weinberg principle independently
What are selection signatures?
differences in genome based on how evolved (?) (domesticated vs non-domesticated will have a big difference in selection signatures)
How can the frequency if an allele in a population be calculated?
from number of individuals
What does the number of dominant alleles at a locus equal?
2 alleles for each homozygous dominant individual plus 1 allele for each heterozygous individual
What does the number of recessive alleles at a locus equal?
2 alleles for each homozygous recessive individual plus 1 allele for each heterozygous individual
What does PKU stand for?
Phenylketonuria
What is PKU?
a metabolic disorder that results from homozygosity for a recessive allele; they cannot break down phenylalanine which results in a build up of it and mental retardation
How is PKU still in the population?
rare deleterious recessives often remain in a population because they are hidden in the heterozygous state (carriers)
When can natural selection act? (like in terms of PKU)
only on the homozygous individuals where the phenotype is exposed (individuals who show symptoms of PKU)
What is interesting about loci and Hardy Weinberg Equilibrium?
in natural populations, some loci can be out of Hardy Weinberg equilibrium, while being in Hardy Weinberg equilibrium at other loci
