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Evolutionary biology > Exam 2 > Flashcards

Exam 2 Flashcards

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1
Q

Evolution

A

Change in allele frequency in a population over time

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2
Q

Natural selection

A

unequal reproduction among individuals in a population based on phenotype

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3
Q

What are the five Hardy-Weinberg Assumptions?

A

No natural selection
No mutation
No migration
No mate preference
No genetic drift

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4
Q

With the Hardy-Weinburg model there is ______________ in allele frequency in a population over time.

A

NO change

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5
Q

What is the formula for Hardy-Weinburg?

A

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

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6
Q

When population is infinite and no evolutionary mechanisms at play, alleles combine _______________ (and in proportions to their frequencies) to form zygotes of next generation

A

randomly

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7
Q

Random mating is called

A

panmyxia

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8
Q

With pocket mice coloration was affected by the ________ locus

A

Mc1R

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9
Q

The two alleles of the coloration of dark mice were D and d. Dd=_______________ and dd=_______________

A

dark coats; light coats

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10
Q

Mismatch of light mice on dark substrate had survival of _______________

A

60-98%

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11
Q

In pocket mice, selection was against ____________ allele

A

d (light)

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12
Q

What is selection coefficient?

A

Quantification of strength of natural selection

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13
Q

The larger the selection coefficient the ________________ the action of natural selection

A

stronger

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14
Q

What was kuru?

A

a disease of the fore people of Papua New Guinea (epidemic in the late 1950s)

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15
Q

1976 _______________________became co-recipient of the Nobel Prize in Medicine for his “discoveries concerning new mechanisms for the origin and dissemination of infectious diseases.”

A

Carleton Gajdusek

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16
Q

What are the types of selection?

A

frequency independent and frequency dependent

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17
Q

Frequency independent selection is:

A

directional
overdominance (heterozygous advantage)
underdominance

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18
Q

Frequency dependent selection is:

A

positive and negative frequency dependence

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19
Q

Directional selection is where

A

one locus is favored over another

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20
Q

Overdominance:

A

Has a heterozygous advantage
Maintains allelic diversity in populations

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21
Q

Underdominance:

A

Selection against the heterozygote
Leads to fixation to one allele or the other depending on starting frequency

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22
Q

With frequency dependent selection the positive side-

A

More common allele is at fitness advantage
Fixation is inevitable

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23
Q

With frequency dependent selection the negative side-

A

Less common allele is at fitness advantage
Maintains allelic diversity in a population

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24
Q

Mutations are the ultimate source of ______________

A

variation

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25
Q

Mutations are __________ and there is no way for them to _______ future needs of organisms or occur when organisms “need” them

A

random; predict

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26
Q

Most mutations are neutral or at least slightly ____________

A

deleterious

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27
Q

Mutation as a ____________________ is very slow, but it can be significant given enough time

A

force of evolution

28
Q

Favorable mutations can quickly become fixed in a population via ___________________

A

selection

29
Q

Cell size _____________ over generations, large jumps indicate dramatic advantage of new mutations

A

increase

30
Q

many mutations are deleterious, and we expect they well be eliminated by _________________

A

selection

31
Q

if selection pressure is ______, and mutation rate is ______ for deleterious allele, we might find it in population at higher than expected frequencies.

A

low; high

32
Q

If allele is recessive, this _________________________ (mutation selection balance) is expressed

A

equilibrium frequency

33
Q

What is the equation for equilibrium frequency?

A

q=√(μ/s)

μ = mutation rate, s = selection coefficient (small: no effect to large: highly deleterious)

34
Q

Spinal muscular atrophy results from loss-of-function alleles of the ________________

A

telSMN locus

35
Q

Assortative mating: preferential mating between individuals with ____________ phenotypes

A

SIMILAR

36
Q

Disassortative mating: preferential matings between individuals with ______________ phenotypes

A

DIFFERENT

37
Q

Inbreeding is:

A

assortive
alleles are identical by descent
(F statistic)

38
Q

Inbreeding depression causes

A

Reduction in fitness due to matings between genetic relatives

More risk of bringing deleterious recessive mutations together

39
Q

Dissassortive mating involves

A

Mate with different phenotype
Increases heterozygotes

40
Q

MHC preferences in humans involves

A

Large chromosomal region (over 200 genes)
Highly polymorphic
Involved in immune recognition

41
Q

Migration is

A

Movement of alleles between population
Adults
Juveniles
Zygotes (seeds)
Gametes (pollen)

42
Q

Migration homogenzies involves

A

With no opposing force (NS), migration tends to equalize allele frequencies

Example: Red bladder campion

43
Q

What is genetic drift?

A

Only completely random mechanism of evolution

44
Q

What does genetic drift result from?

A

random combination of alleles

45
Q

Without infinite population sizes, ___________ may not combine in their expected mathematical probabilities

A

gametes

46
Q

Genetic drift:

A

Deviations from expected frequencies due to chance effects in small populations

47
Q

Genetic drift results in

A

Alleles fluctuate over time (without NS)
Alleles become fixed/lost
Frequency of heterozygotes decreases
Different populations experience different changes in allele frequency producing divergence

48
Q

What are the two types of genetic drift?

A

Founder effect
Bottleneck

49
Q

___________ populations experience more drift

A

Smaller

50
Q

What is heterozygosity?

A

measure of variation in the population

51
Q

What is OBSERVED heterozygosity?

A

fraction of individuals in a population who are heterozygotic at a particular loci

52
Q

What is EXPECTED heterozygosity?

A

using allele frequencies from population, the fraction of heterozygotes predicted under H-W model

53
Q

Wright-Fisher Model

A

predicts loss of heterozygosity by a factor of 1/2N with N as population size

54
Q

Rate of loss is _____________ proportional to population size

A

inversely

55
Q

What describes an effective population size?

A

Uneven sex ratio
Age structure
Fluctuations in pop size

56
Q

Microsatellites

A

Act as selectively neutral, highly variable alleles

57
Q

Selection strong and population large: ______________________more of a force

A

natural selection

58
Q

Selection week and population small: _________________ is more of a force

A

genetic drift

59
Q

Genetic drift __________ the probability of identity by descent over time

A

increases

60
Q

phenotypic plasticity

A

Genotype different phenotypes in different environments (reaction norm)

61
Q

What are some types of mutations?

A

Point mutations
Indels
Gene duplication
Inversions
Genome duplication

62
Q

What type of mutations affect alleles?

A

point mutations
Indels–insertion deletions

63
Q

What mutation affects genes?

A

gene duplication (polyploidy) (unequal crossing over, retroduplication (pseudogene)

64
Q

What mutation affects chromosomes?

A

Inversions
Genome Duplication

65
Q

What were the two hypotheses of the Luria Delbruck Experiment?

A

1.environment induced–equal distribution of resistance across cultures
2.spontaneous–unequal distribution

66
Q

What did the Luria Delbruck experiment include?

A

Culture E. coli in a tubes with non selective media
Split into separate cultures and then grew on agar plates with a bacteriophage

Evolutionary biology (1 decks)

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