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From Organisms to Ecosystems - Lectures > Lecture 17. The Principles of Population Genetics > Flashcards

Lecture 17. The Principles of Population Genetics Flashcards

1
Q

What does genetic variation diploid populations arise from ?

A

Mutation and sexual reproduction

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2
Q

What does mutation allow ?

A

New variants

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3
Q

What does sexual reproduction allow ?

A

Variations to be continuously recombined in unique formations

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4
Q

What are a pair of homologous chromosomes defined by ?

A

Their ability to pair up during meiosis

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5
Q

What is a locus ?

A

A fixed position on a chromosome

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6
Q

What are alleles ?

A

Alternate versions of the DNA sequences that occur at the same locus on homologous chromosomes

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7
Q

What are the most commonly observed types of mutation ?

A

Single nucleotide variant

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8
Q

What is the genotype ?

A

The genetic material possessed by an individual at a given locus

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9
Q

What is the gene pool ?

A

The sum of all alleles in the breeding members of a population at any given time

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10
Q

In a diploid population of N individuals how many N alleles is there at an autosomal locus ?

A

2N alleles

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11
Q

What do we describe the gene pool in terms of ?

A

Allele and genotype frequencies

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12
Q

What is the formula for allele frequency F(A) ?

A

Allele count/Total number of alleles

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13
Q

What is the formula for a biallelic variant ?

A

F(A) + F(a) = p + q = 1

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14
Q

What is a single nucleotide polymorphism ?

A

A relatively common single nucleotide variant

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15
Q

What is a minor allele ?

A

Low frequency in the population

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16
Q

What is the major allele ?

A

Higher frequency in population

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17
Q

What is the genotypic frequency formula F(AA) ?

A

Genotype count/Total number of individuals

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18
Q

What is the genotypic frequency for a biallelic variant ?

A

F(AA) + F(Aa) + F(aa) = 1

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19
Q

What is a core concept if we have observed the genotype frequencies of a population ?

A

We can calculate the allele frequencies

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20
Q

What is a core concept about knowing the allele frequencies of a population ?

A

We can predict the expected genotype frequencies

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21
Q

When is a population in hardy weinberg equilibrium ?

A

If its observed genotype and allele frequencies do not change through the generations. They remain constant

22
Q

What does it take to bring genotypes to equilibrium proportions ?

A

One generation if random mating

23
Q

What does hardy weinberg equilibrium require ?

A
  1. Random combination of alleles at each generation - random mating
  2. No change in allele frequencies between generations - no evolution
24
Q

What are some violations to random mating ?

A
  1. Geography ie setting a limit
  2. Phenotype
  3. Interbreeding
25
Q

What is the principle of random mating ?

A

All other individuals in the population must be equally likely to be chosen as a mate

26
Q

What is a characteristic of the Wahlund effect ?

A

Lack of heterozygotes

27
Q

What is the wahlund effect

A

Non random mating

28
Q

What does non-random mating not change ?

A

Allele frequencies

29
Q

Is a population in hardy weinberg equilibrium evolving ?

A

No

30
Q

If there is still random mating in the observed genotype what will their frequencies do ?

A

They will match those expected within any single generation

31
Q

What are the violations in the hardy weinberg equilibrium that lead to evolution ?

A
  1. Mutation
  2. Genetic drift
  3. Gene flow/migration
  4. Selection
32
Q

What does mutation do ?

A

Changes the allele frequency by creating a new variant

33
Q

How will a mutation change the minor allele frequency at an invariant locus ?

A

Change it from 0 to 1/2N

34
Q

What is genetic drift also known as ?

A

Sampling error

35
Q

What is genetic drift ?

A

Alleles are sampled at random from the gene pool to contribute to the next generation

36
Q

In genetic drift, when is error smaller ?

A

The larger the sample size

37
Q

Where is random drift stronger ?

A

In smaller populations

38
Q

Where is random drift weaker ?

A

In larger populations

39
Q

What are some extreme examples of genetic drift ?

A
  1. Population bottleneck

2. Founder effect

40
Q

What is population bottleneck ?

A

Reduction in overall population size due (chance)

41
Q

What is the founder effect ?

A

Isolation of a small fraction of the population from the larger group

42
Q

What is gene flow ?

A

The movement of genetic material from one population to another

43
Q

What does isolation lead to ?

A

Divergence in allele frequencies

44
Q

What is genetic differentiation ?

A

Accumulation of allele frequency differences due to restricted gene flow

45
Q

What allows for gene flow ?

A

A reduction in the barriers to mating

46
Q

What is admixture ?

A

Gene flow between two or more genetically distinguishable populations

47
Q

What can be considered if gene flow is high enough ?

A

The two populations can be considered a single random mating population

48
Q

What happens if gene flow is low enough ?

A

Subpopulations can be detected through allele frequencies differences called population structure

49
Q

Where are clines observed ?

A

When gene flow occurs more frequently between neighboring groups

50
Q

Why are populations always evolving ?

A
  1. Mutation is inevitable
  2. Population sizes are finite
  3. The earth is dynamic - continuous isolation and flow
51
Q

What is selection ?

A

A non-random change in allele frequencies due to interactions between phenotype and environment

From Organisms to Ecosystems - Lectures (37 decks)

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