LeCTURE 38 pOPUlation Genetics

What is a Mendelian Population? How does a geneticist define evolution?

A Mendelian Population is a group of interbreeding, sexually reproducing individuals with a common set of genes (gene pool)

Evolution is defined as a change in allele frequencies in a population’s gene pool across generations

What 4 forces shape the gene pool? Which adds and which removes genetic variation from the gene
pool?

1. Mutation - adds to gene pool

2. Genetic Drift - removes from the gene pool

3. Migration - adds to the gene pool

4. Selection - adds AND removes to the gene pool

What does inbreeding do to the gene pool?

Inbreeding is going to INCREASE HOMOZYGOSITY decreasing genetic variation

INCREASES FREQUENCY OF NEGATIVE ALLELES

What is the difference between a deterministic and stochastic model?

Deterministic model makes EXACT PREDICTIONS

Stochastic model DOES NOT GIVE EXACT PREDICTIONS, allows for RANDOM ACTION

What do p and q stand for?

p = f(A) = the frequency of the dominant allele A

q = f(a) = the frequency of the recessive allele a

Know the Hardy-Weinberg Equilibrium equation (yes the actual equation)!

p² + 2pq + q² = 1

p² = f (AA) homozygous dominant
2pq = f (Aa) heterozygous
q² = f (aa) homozygous recessive

How do drift and selection differ?

Drift is the random changes in allele frequencies due to chance

Selection are NON RANDOM changes driven by fitness differences

How does migration affect drift and selection?

Migration adds genetic variation to the gene pool mitigating the effects of drift and adding more genes for selection to work with.