,20. Understand the intimate relationship between populations and genetic diversity
A. Calculate allele frequencies given genotype frequencies or number of individuals
with each genotype
B. Explain (in your own words) the predictions of the Hardy-Weinberg (HW) Principle.
HWP predicts: the genotype and allele frequencies of the next generation from
given set of parental allele frequencies
HW principle makes 2 fundamental claims:
1. If frequencies of alleles A and a in a population are given by p and q, then
the frequencies AA, Aa, and aa will be given by p2, 2pq, and q2, respectively,
for generation after generation.
allele frequencies: p + q = 1
genotype frequencies: p2 + 2pq + q2 = 1
2. When alleles are merely transmitted via meiosis and random combinations
of gametes, their frequencies do not change over time, meaning that no
evolution occurs
C. List and restate (in your own words) the five assumptions/conditions of the
Hardy- Weinberg principle, and know under which conditions it is OK to make these
assumptions, or why you are testing for violations of these assumptions.
Assumptions:
1. Random mating
- Gametes from gene pool combine at random
- Individuals not allowed to choose a mate
2. No natural selection
- All members of parental generation survive
- They contribute equal numbers of gametes to gene pool, regardless of
genotype
3. No genetic drift (random allege frequency change)
- Alleles are picked in exact frequencies p and q, rather than by chance
- Population is infinitely large
4. No gene flow
- No new alleles are added by immigration, lost through emigration
- All of alleles in offspring population come from original population’s
gene pool
5. No mutation
- No new alleles introduced into the gene pool
Allele frequency changer (thus processes of evolution): natural selection, genetic
drift, gene flow, mutation
Genotype frequency changer: nonrandom mating
, Selection is the only evolutionary force that consistently results in adaptation.
Mutation without selection and genetic drift are random processes that may lead to
adaptive, maladaptive, or neutral effects on populations.
Generation-to-generation change in the allele frequencies in a population is the definition of
microevolution.
D. Predict allele and genotype frequencies of rare genetic disorders in a population from
phenotypic data alone, ASSUMING that the population is in Hardy-Weinberg Equilibrium,
and understand the limitations of your estimates.
Use the following steps to determine if the population may be evolving.
Determine the total number of alleles in the population.
Determine the frequency of each allele in the population.
Use the equation for Hardy-Weinberg equilibrium to determine the expected frequency of each
genotype. (See Hint 2.)
Based on the expected frequency of each genotype, calculate the expected number of
individuals with each genotype.
Compare the expected number of individuals with each genotype to the actual number of
individuals with each genotype.
If the expected number of individuals with each genotype differs from the actual number of
individuals with each genotype, then the population may be evolving.
E. Calculate the expected frequencies of offspring of particular genotypes or
phenotypes expected in the next generation if the population is in Hardy–Weinberg
equilibrium given allele or genotype frequencies in the current generation
F. Be able to apply the Hardy–Weinberg equation to estimate the frequencies of
carriers in a population, assuming alleles of the gene in question is in Hardy–Weinberg
Equilibrium
G. Understand in what sense the Hardy-Weinberg equation represents the prediction
of the null hypothesis of biological evolution.
Null hypothesis: specified what should be observed if the hypothesis being tested is
not correct; status quo
HW principle functions as null hypothesis because: biologists often want to test a
hypothesis that nonrandom mating is occuring/evolutionary processes is affecting
particular trait in population
H. Determine whether or not a population is in Hardy-Weinberg equilibrium using the Chi-
Square statistic to compare expected and observed genotype frequencies of a
population, and explain the biological implications of either rejecting or failing to reject
the null hypothesis based on your results.
A. Calculate allele frequencies given genotype frequencies or number of individuals
with each genotype
B. Explain (in your own words) the predictions of the Hardy-Weinberg (HW) Principle.
HWP predicts: the genotype and allele frequencies of the next generation from
given set of parental allele frequencies
HW principle makes 2 fundamental claims:
1. If frequencies of alleles A and a in a population are given by p and q, then
the frequencies AA, Aa, and aa will be given by p2, 2pq, and q2, respectively,
for generation after generation.
allele frequencies: p + q = 1
genotype frequencies: p2 + 2pq + q2 = 1
2. When alleles are merely transmitted via meiosis and random combinations
of gametes, their frequencies do not change over time, meaning that no
evolution occurs
C. List and restate (in your own words) the five assumptions/conditions of the
Hardy- Weinberg principle, and know under which conditions it is OK to make these
assumptions, or why you are testing for violations of these assumptions.
Assumptions:
1. Random mating
- Gametes from gene pool combine at random
- Individuals not allowed to choose a mate
2. No natural selection
- All members of parental generation survive
- They contribute equal numbers of gametes to gene pool, regardless of
genotype
3. No genetic drift (random allege frequency change)
- Alleles are picked in exact frequencies p and q, rather than by chance
- Population is infinitely large
4. No gene flow
- No new alleles are added by immigration, lost through emigration
- All of alleles in offspring population come from original population’s
gene pool
5. No mutation
- No new alleles introduced into the gene pool
Allele frequency changer (thus processes of evolution): natural selection, genetic
drift, gene flow, mutation
Genotype frequency changer: nonrandom mating
, Selection is the only evolutionary force that consistently results in adaptation.
Mutation without selection and genetic drift are random processes that may lead to
adaptive, maladaptive, or neutral effects on populations.
Generation-to-generation change in the allele frequencies in a population is the definition of
microevolution.
D. Predict allele and genotype frequencies of rare genetic disorders in a population from
phenotypic data alone, ASSUMING that the population is in Hardy-Weinberg Equilibrium,
and understand the limitations of your estimates.
Use the following steps to determine if the population may be evolving.
Determine the total number of alleles in the population.
Determine the frequency of each allele in the population.
Use the equation for Hardy-Weinberg equilibrium to determine the expected frequency of each
genotype. (See Hint 2.)
Based on the expected frequency of each genotype, calculate the expected number of
individuals with each genotype.
Compare the expected number of individuals with each genotype to the actual number of
individuals with each genotype.
If the expected number of individuals with each genotype differs from the actual number of
individuals with each genotype, then the population may be evolving.
E. Calculate the expected frequencies of offspring of particular genotypes or
phenotypes expected in the next generation if the population is in Hardy–Weinberg
equilibrium given allele or genotype frequencies in the current generation
F. Be able to apply the Hardy–Weinberg equation to estimate the frequencies of
carriers in a population, assuming alleles of the gene in question is in Hardy–Weinberg
Equilibrium
G. Understand in what sense the Hardy-Weinberg equation represents the prediction
of the null hypothesis of biological evolution.
Null hypothesis: specified what should be observed if the hypothesis being tested is
not correct; status quo
HW principle functions as null hypothesis because: biologists often want to test a
hypothesis that nonrandom mating is occuring/evolutionary processes is affecting
particular trait in population
H. Determine whether or not a population is in Hardy-Weinberg equilibrium using the Chi-
Square statistic to compare expected and observed genotype frequencies of a
population, and explain the biological implications of either rejecting or failing to reject
the null hypothesis based on your results.
