Lecture 3 Flashcards

1
Q

Why do we model genotypic effects from allelic values?

A

Because individuals pass on alleles not genotypes

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2
Q

What are the average allele effects?

A

The average deviation of individuals who received the allele from one parent and the other allele randomly from the population.

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3
Q

What are breeding values?

A

Summation of the average allele effects, they are additive. They depend on a and d, because alpha=a+(q-p)d.

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4
Q

What is the equation for genotypic variance?

A

Genotypic variance = additive genetic variance + dominance variance

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5
Q

Explain the concept of genetic drift.

A

Under random mating, no mutations and no migration:

  • in large populations allele frequencies remain constant over generations
  • in small populations allele frequencies change by chance aka random drift
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6
Q

What two things does random drift cause?

A

Increase in homozygosity

Reduction in genetic variance

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7
Q

In small populations, what is related to genetic drift?

A

Inbreeding

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8
Q

What does the inbreeding coefficient tell us?

A

The probability that two alleles in a locus are identical by descent (allele came from the same ancestor)

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9
Q

What is does it mean to be identical by descent? (In reference to new inbreeding and genetic drift)

A

The probability of two gametes taken from the population carry identical alleles from the same ancestor.

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10
Q

What is the definition association with old inbreeding in reference to genetic drift?

A

Probability of two gametes taken randomly from the population from different ancestors carry identical by descent alleles.

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11
Q

What are the 4 conditions and 2 characteristics of two unlinked loci? What do these conditions mean in terms of possible gametes?

A

In large populations under random mating, no selection, no mutations and no migration.
The two loci are in: HW equilibrium within locus and joint gametic phase equilibrium.
Means that the probability of possible gametes are given by the product of allele frequencies, because alleles are independent.

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12
Q

How do two unlinked loci behave in disequilibrium?

A

D is halved by one generation of random mating

r=0.50

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13
Q

How do two linked loci behave in disequilibrium?

A

When r=0.5 they behave like unlinked loci where one generation of random mating halves D.
When r<0.5 it will take longer to reach equilibrium by random mating

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