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Genetics > Lesson 11 Population Genetics > Flashcards

Lesson 11 Population Genetics Flashcards

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Biology 101 flashcards
1
Q

Gene pool

A

Total of all genes within a particular population

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2
Q

Population

A

A group of individuals of the same species that are capable of interbreeding with one another. Dynamic units that change size, location and genetic composition.

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3
Q

polymorphism

A

Many traits display variation within a population, either phenotypically or genetically.

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4
Q

polymorphic gene

A

Exists as two or more alleles in a population

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5
Q

monomorphic gene

A

Exists predominantly as a single allele in a population. Found in 99 percent or more cases.

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6
Q

allele frequency

A

No. Of copies of allele in population/
Total no. Of all alleles for that gene in population

Relative percentage of an allele of a given green

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7
Q

Genotype frequency

A

No. Of individuals with a particular genotype in a population/
Total number of individuals in a population

Relative percentage of a given genotype

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8
Q

Use of hardy-Weinberg equation

A

Used to calculate genotype frequencies based on allele frequencies

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9
Q

Hardy Weinberg equation

A

p^2 + 2pq + q^2 = 1
p^2 = genotype frequency of AA
2pq = genotype frequency of Aa
q^2 = genotype frequency of aa

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10
Q

What conditions must be met for Hardy Weinberg equation to work?

A

Large population, random mating, no migration, no natural selection, and no mutations

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11
Q

assortative mating

A

When two individuals are more likely to mate due to similar phenotypic characteristics

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12
Q

disassortative mating

A

When unlike phenotypes mate

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13
Q

inbreeding

A

When two genetically related individuals mate with each other

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14
Q

outbreeding

A

Mating between unrelated individuals

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15
Q

coefficient of inbreeding (F)

A 
F = Sum (1/2)^n (1 + Fa)
n = number of individuals in the inbreeding path
Fa = inbreeding coefficient of the common ancestor
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16
Q

Inbreeding: common ancestor

A

Someone who is an ancestor to both fo an individual’s parents

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17
Q

Size of inbreeding path

A

The shortest no. Of steps through the pedigree that includes both parents and the common ancestor. Calculated by adding together all of the individuals in the path except for the individual of interest.

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18
Q

Measuring effects of inbreeding at population level

A

Frequency of AA= p^2 + Fpq
Frequency of Aa = 2pq (1-F)
Frequency of aa = q^2 + Fpq

19
Q

What is effect of inbreeding

A

Lower the relative number of heterozygotes

20
Q

Two types of evolutionary forces

A
  1. Neutral forces

2. Adaptive forces

21
Q

Neutral forces

A

Alter allele frequencies in a random manner. Without regard to survival of the individual.

22
Q

Adaptive forces

A

“select” for the survival of individuals who possess alleles that make them well adapted to their environment

23
Q

What do new mutations provide a population?

A

Genetic variability

24
Q

Mutation rate

A

Likelihood that a gene will be altered by a new mutation; expressed as the number of new mutations Ina given gene per generation
10^5 to 10^6 per generation

25
Q

Random genetic drift

A

Random changes in allele frequencies due to sampling error

26
Q

What does rate at which allele becomes fixed depend on?

A

Population size

27
Q

Probability of fixation

A

1/2N (assuming an equal no. Of males and females contributing to the next generation)

28
Q

Probability of elimination

A

1 - 1/2N

29
Q

time it will take for fixation to occur

A

Mean t = 4N

Mean t = average no. Of generations to achieve fixation. N equals the no. Of individuals in a population.

30
Q

How is random genetic drift directional?

A

It leads to allele fixation or elimination

31
Q

When are allele frequencies altered?

A

When migration occurs between two populations

32
Q

conglomerate

A

Population after migration has occurred

33
Q

change in allele frequency in conglomerate population

A

deltaPc = m(Pd - PR)
DeltaPc is change in allele frequency
Pd is allele frequency in donor population
PR is allele frequency in original recipient population

m = no. Of donor individuals in cong. population/
Total no. Of individuals in cong. population

34
Q

Natural selection

A

Conditions found in nature select for the survival of individuals who have characteristics that make them well adapted to their environment t

35
Q

Darwinian fitness (W)

A

Relative likelihood that a phenotype will survive and contribute to the gene pool of the next generation compared to another phenotype

36
Q

Selection coefficient

A

Measure of the degree to which a genotype is selected against

s = 1 - W

37
Q

What does process of natural selection result in

A

An increase in the mean fitness of the population

38
Q

Balanced polymorphism

A

A polymorphism that exists because an equilibrium has been achieved between the genotype and the environment

39
Q

Why might balanced polymorphism occur?

A

Heterozygote selective advantage or a species may occupy a region that contains heterogeneous environments

40
Q

How is higher fitness of heterozygote balanced in balanced polymorphism?

A

Allele frequency of A = Saa / SAA + Saa

Allele frequency of a = SAA/SAA + Saa

41
Q

Experiment 25A: natural selection in moths

hypothesis

A

The coloration of b. betularia affects the probability that birds will see and eat them. This natural selection leads to the survival of those moths with coloration more closely matching that on which they rest, whether that be in polluted or unpolluted woods.

42
Q

Experiment 25A: natural selection in moths

Starting materials

A

Samples of b. betularia, broth carbonaria and ty0pical, were collected from the wild. In some cases, they were bred in a lab, to be released later into the wild.

43
Q

Experiment 25A: natural selection in moths

protocol

A
  1. mark the underside of carbonaria and typical moths with cellulose paint
  2. Release equal numbers of marked carbonaria and typical moths in either polluted woods near an industrial area of Birmingham or in an unpolluted woods in Dorset, England
  3. On several consecutive days, recapture moths that have been marked. This can be done by attract ting them to a mercury vapor light. Record the number of recaptured moths.
  4. Also, sit in a blind and observe the moths on a tree trunk. Record the numbers and types of sitting moths that are eaten by birds.
44
Q

Experiment 25A: natural selection in moths

Interpreting the data

A

carbonaria were more likely to be eaten in unpolluted woods by birds.
Typical were more likely to be eaten in polluted woods
Birds act as selective agents and the the melanic forms of betularia are Ata. Cryptic advantage in an industrial area.

Genetics (12 decks)

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