theme 4b- population genetics

Question 1

what is a population?

Answer 1

interbreeding group of individuals that belong to the same species and live within a restricted geographical area

Question 2

what is the null hypothesis for evolution?

Answer 2

there will be no change in allele frequencies over time

Question 3

what were the 5 assumptions of hardy and weinburgs population?

Answer 3

1. no mutations, no new alleles
2. no gene flow from other populations
3. the population is very big
   4.natural selection doesn’t affect the alleles
4. random mating

Question 4

what happens to the allele frequencies if the H+W assumptions are correct?

Answer 4

allele frequencies are constant between generations

Question 5

what is random mating?

Answer 5

gametes unit randomly

Question 6

what is the probability theory?

Answer 6

probability of two independant events occuring together is the product of their individual probabilities (event 1* event 2= probaility)

Question 7

what is the HW equilibrium equation?

Answer 7

p^2+2pq+q^2=1

Question 8

what can you do to return a population to HW equilibrium?

Answer 8

one round of random mating with the other conditions met (no evolution or migration and a big population) will return the population to equilibrium

Question 9

what is hardy weinburg the null hypothesis for?

Answer 9

change in allele frequency

Question 10

why is HWE a powerful test in evolution?

Answer 10

-tells us when evolution is not occuring
-Departure from equilibrium suggests that one or more of the assumptions has been violated
-predicts allele frequency when we don’t have other information

Question 11

how to test if a population is in HWE?

Answer 11

1. Calculate allele frequencies, p and q
2. Use allele frequencies to calculate expected genotype frequencies: p2 , 2pq , q2
3. Calculate expected numbers under HWE
4. Compare observed to expected (Chi-square test)