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Genetics > CHAPTER 20 > Flashcards

CHAPTER 20 Flashcards

1
Q

Compare mendelian genetics and population genetics

A
  • Generations and relationship among individual: M - known, P - generally unknown
  • Number of analyzed alleles: M - usually two, P - Highly variable
  • Forces influencing individuals/populations: M - known and controlled, P- unknown and inferred
  • Mode of reproduction: M - Known, P - from known to unknown depending on organism
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2
Q

Def: Population

A

a group of interbreeding organisms

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3
Q

Def: Gene pool

A

The collection of genes and alleles found in the members of a population

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4
Q

Def: Population genetics

A

The study of allele frequencies and genotype frequencies within and between population

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5
Q

Def: Evolution

A

Changes of allele frequency and genotype frequency over time

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6
Q

Hardy-Weinberg equilibrium

A

Populations with observed genotype frequencies at individual loci not different from expected based on random mating

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7
Q

HWE equation

A

p^2 + 2pq + q^2 = 1

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8
Q

Assumptions of Hardy-Weinberg equilibrium

A
  1. Population size is infinite
  2. Random mating occurs in the population, allowing genotype frequencies to be predicted by allele frequencies
  3. Natural selection does not operate
  4. Migration does not introduce new alleles
  5. Mutation does not introduce new alleles
  6. Genetic drift does not occur
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9
Q

Predictions of HWE

A
  1. Allele frequencies remain stable over time
  2. Allele distribution into genotypes is predictable
  3. Stable equilibrium frequencies of alleles and genotypes are maintained
  4. Evolutionary and nonrandom mating effects are predictable
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10
Q

Calculating expected genotype and allele frequencies in HWE for more than two alleles

A

ALLELE FREQUENCIES
p + q + r = 1

GENOTYPE FREQUENCIES
p^2 + 2pq +2pr + q^2 + 2qr + r^2 = 1

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11
Q

How to determine autosomal allele frequencies from genotype frequencies in populations

A
  1. The gene-counting method: co-dominant alleles
  2. The square root method
    - Dominant-recessive alleles, assumes HW equilibrium
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12
Q

Major forces that change allele frequencies in a population over time

A

SOURCES OF GENETIC VARIABILITY
- Mutation
- Mode of reproduction
- Gene flow
Lead to population-environmental interactions
- Natural Section
- Genetic drift
ALL LEAD TO EVOLUTION

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13
Q

Directional artificial selection favoring the AdhF allele in experimental Drosophila population

A
  • In high frequency AdhF in high ethanol environment
  • Relatively stable frequencies in zero-ethanol environment
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14
Q

Balanced polymorphism

A

Alleles reach stable equilibrium frequencies that are maintained in a steady state balancing the selective pressures favoring the maintenance of a mutant allele when it occurs in a heterozygote but acting against it when it occurs in a homozygous genotype

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15
Q

Allele frequencies in balanced polymorphsims

A
  • t: fitness disadvantage of cc vs Cc
  • s: fitness disadvantage of CC vs Cc
  • pe (allele frequency C) = t/(s+t)
  • qe (allele frequency c) = s/(s+t)
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16
Q

Forward Mutation rate

A

u
The rate of creating new alleles

17
Q

Reverse mutation rate

A

v
rate of mutation to original allele

18
Q

Results of gene flow

A
  • Introduce novel alleles
  • Increase frequency pf existing alleles
  • Remove/reduce existing alleles
  • Create admixed population
19
Q

Genetic drift

A

chance fluctuations of allele frequencies due to sampling bias

20
Q

Inbreeding

A

Mating between related individuals - increases homozygous genotypes

21
Q

Biological species concept

A

a group of organisms capable of interbreeding with each other but isolated from other species

22
Q

Allopatric speciation

A

populations diverge due to physical barrier and thus new species develop in separate geographic locations

23
Q

Sympatric speciation

A

populations share a territory but are isolated by genetic, behavioral, seasonal, or ecosystem-based mechanisms that prevent gene flow

24
Q

Hybrid speciation

A

formation of new species due to hybridization between existing species

25
Q

Prezygotic mechanism of reproductive isolation

A
  • Behavioral
  • Gametic
  • Geographical
  • Habitat
  • Mechanical
  • Temporal
26
Q

Postzygotic mechanisms of reproductive isolation

A
  • hybrid breakdown: deceased fitness of F1 progeny
  • Hybrid inviability: fails to survive gestation
  • Hybrid sterility
27
Q

Mutation-selection balance

A
  • equilibrium frequence of recessive allele qE = sqrt(u/s)
    u = mutation rate
    s = selection co-efficient against mutant allele
28
Q

Fonder effect

A

The reduced genetic diversity when a population is descended from a small number of colonizing ancestors

29
Q

Genetic bottleneck

A

event limits generation size or genetic variation, large genetic drift effect

Genetics (18 decks)

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