Population Genetics HW principle

Question 1

What can we use from genotype or allele frequencies?

Answer 1

We cannot calculate genotype frequencies based on allelic frequencies = for example, may have no heterozygotes….

BUT
You can always calculate allelic frequencies from genotype frequencies….

F(a) = F(aa) + 1/2 Aa
F(A) = F(AA) + 1/2 Aa

Question 2

What is the point of HW principle?

Answer 2

HW enables calculation of GENOTYPE frequencies using allelic frequencies, BUT only if certain conditions are met…
(Usually you can’t calculate genotype frequencies based on allelic frequencies).

Question 3

What are the conditions to satisfy HW principle?

Answer 3

There is no selection for alleles.

Random mating = panmixia

Large (infinite) population size.

No overlap in generations.

Mutation and migration are absent.
allelic frequencies are the same between male and female.
Sufficiently large population.

Question 4

What is genetic drift?

What is allele frequencies?
Genotype frequencies?

Answer 4

When populations are small enough, sampling results in different allele frequencies from one generation to the next (by chance).

Proportion of any specific allele in a population, estimated from genotype frequencies.

Proportio of individuals in a population with a specific genotype.

Question 5

What is a subpopulation?

Local population?

Answer 5

Breeding group within a population among which migration is restricted.

Within the subpopulation, most people find their maters

Question 6

What is a population?

Answer 6

a group of organisms of the same species in same geographical area.

Question 7

What is the importance of HW theory?

Answer 7

In the absence of evolutionary forces, and if only random mating is acting, allele frequencies will remain unchanged and genotypic frequencies are constant between generations…

It is useful as a null hypothesis = can see how a population deviates from HW frequencies to infer the forces of evolution acting on it.

Question 8

What is HW equation?

Answer 8

P+Q = 1
so when gametes meet containing either A or a alleles, the diploid zygotes will have genotype frequencies of:

P^2 + 2PQ + Q^2

Question 9

What is heterozygote superiority?

Answer 9

When viability and fertility (fitness) of heterozygote is greater than both homozygotes.

= Neither allele can be eliminated by selection (as heterozygotes favourable)…

In the case of Sickle cell anaemia, heterozygotes are fitter since more resistant to malaria and healthy.