Lecture 34 Flashcards

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1
Q

What is Hardy Weinberg equilibrium?

A

-genotypes are in the proportions if p= f(A) allele q = f(a) allele
p2+2pq+q2=1
p2= f(AA)
2pq=f(Aa)
q2=f(aa)
-remaining constant across generations
This equilibrium acts as a reference point for all population genetics studies
However constancy of allele frequencies does not necessarily
indicate a Hardy-Weinberg equilibrium
-when you have hardy weinberg equilibrium you can maintain the genotypic proportions from generation to generation

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2
Q

What are the 5 assumptions of the Hardy-Weinberg law?

A
  1. Random mating=equally likely to mate with everyone, no preference allowed
  2. No migration (no gene flow)= no new alleles brought in
  3. No selection acting= once a partner equally likely to have the same no. of offspring, none is more fit than the other
  4. No mutation=no new alleles, or equally in both direction
  5. Infinite population size = large enough to prevent sampling errors and random effects
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3
Q

What does H-W refer to?

A

-genotypic frequencies remaining constant in the proportion and as a consequence constant allele frequencies result

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4
Q

How do you know if population is in H-W equilibrium?

A

.

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5
Q

What are selective agents?

A

-Factors in the environment which discriminate between phenotypes and or genotypes
eg.,
climate pollution predators disease insecticide antibiotics…….
Fitness can change in different environments

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6
Q

What is w and s?

A

w-fitness and s is the selection against

  • one phenotype always has fitness 1 and anotehr has less
  • s = if w=0 then s=1
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7
Q

what happens in a malarial region?

A

-in non malarial region HbA frequency tends towards monomorphism

malarial region = constant allele frequencies= stable or balanced polymorphism = but not HW because there is selection!
conclusion from sickle cell study: selection may alter allele frequencies or keep them constant

so sometimes even when have stable allele frequencies= doesn’t have to be HW equilibrium

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