Lecture 11 Flashcards

1
Q

in DNA fingerprinting, why do you need to look at a lot of loci to prove someone is guilty?

A

with only a few loci, it is possible that many people will have the same combination of alleles at the diff loci

with more loci, it is easier to find a match to just 1 person bc less likely that more than 1 person will have same combo

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2
Q

is inbreeding random? what does this mean about frequencies?

A

inbreeding is NON-RANDOM –> HW frequencies don’t apply

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3
Q

what phenomenon occurs in inbreeding?

A

alleles are IDENTICAL BY DESCENT

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4
Q

what does it mean for alleles to be identical by descent?

A

2 alleles at a locus that are copies of an allele found in an ancestor

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5
Q

what is the inbreeding coefficient, F?

A

overall probability that the 2 alleles inherited by an individual will be IBD

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6
Q

how do the numbers of homozygotes and heterozygotes change when there’s inbreeding vs random mating?

A

inbreeding makes MORE homozygotes and FEWER heterozygotes

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7
Q

do genotype or allele frequencies change in inbreeding (vs random breeding)?

A

only GENOTYPE frequencies change

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8
Q

what is inbreeding depression?

A

inbred individuals have reduced viability/survival

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9
Q

why does inbreeding depression occur?

A

deleterious conditions often require 2 copies of the mutation to reduce survival and inbreeding causes increased homozygosity

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10
Q

what are the 4 factors that influence allele frequencies? are they independent of each other?

A
  1. mutation
  2. migration
  3. genetic drift
  4. natural selection
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11
Q

is mutation a major force in influencing allele frequencies?

A

no, mutation rate is very low

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12
Q

what is the rate of mutations per base pair per generation?

A

10^-9 mutations/bp/generation

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13
Q

what is migration?

A

new alleles are introduced from a diff population

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14
Q

2 types of migration

A
  1. unidirectional
  2. bidirectional
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15
Q

describe unidirectional migration

A

similar to mutations, new alleles are introduced every generation

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16
Q

describe bidirectional migration

A

species becomes HOMOGENIZED and prevents populations in a species from diverging

17
Q

what type of populations does genetic drift occur in?

A

small populations only!

18
Q

what occurs in genetic drift?

A

slowly an allele is lost as small population is maintained

19
Q

how does genetic drift affect genetic diversity?

A

genetic diversity is lost with genetic drift

20
Q

if genetic drift and migration were occurring simultaneously, how would the population diverge compared to just genetic drift alone?

A

both genetic drift and migration –> migration would slow down the loss of alleles and population would diverge less quickly

genetic drift –> alleles would be lost and population would diverge quickly