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BIOL 302 - Evolution > midterm > Flashcards

midterm Flashcards

1
Q

Define evolution

A

origin of entities possessing different states of one or more characteristics - and changes in the proportion of those entities over time

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2
Q

Define biological evolution

A

change over timein the proportion of individual organisms within a population differing genetically in one or more traits

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3
Q

Darwin defined evolution as…

A

descent with modification

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4
Q

What was Platos view on the natural world?

A

Platonic idealism - there is an ideal form that is imperfectly represented by earthly representations
- ideal forms can be perceived only through contemplation

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5
Q

What was Aristotles view on the natural world?

A

Essentialism - all members of a class of objects share certain properties that distinguish them from other classes
- species are immutable
- classified species using scala naturae

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6
Q

What was George Cuviers contribution?

A
  • described extinction
    Catastrophism - species are created by catastrophic extinction events
    Father of palaeontology
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7
Q

What was James Huttons contribution?

A
  • Uniformitarianism - natural processes that operated in the past are still ongoing in the present
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8
Q

What was Charles Lyells contribution

A
  • influence on Darwin
  • popularized Huttons uniformitariansm hypothesis
  • change can happen on larger timescales
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9
Q

What was Lamarcks contribution?

A
  • inheritance of acquired characteristics
  • thought evolution had a goal
  • traits acquired by use vs disuse
  • transformism
    Early influence on Darwin
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10
Q

What were the two main theories in the Origin of Species?

A
  • descent with modification and natural selection
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11
Q

What are the five inter related theories of evolution?

A
  • Evolution as such
    -Common descent
  • Gradualism vs saltations
  • Population variation vs. platonic idealism
  • Natural selection - mechanism
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12
Q

Why was Darwin wrong about his mode of inheritcance via blending?

A

would ultimately reduce variation

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13
Q

What are the two main schools of thought on variation of traits?

A
  • Mendelians - large differences - discrete traits - color
  • Biometricians - small differences - quantitative traits - height - believed in natural selection
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14
Q

What did Fisher contribute?

A
  • natural selection could work with mendelian inheritance
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15
Q

What is the modern synthesis?

A

Neo Darwinism
- mendelian inheritance and natural selection

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16
Q

Two types of phenotypic variation

A

discrete (one loci) and continuous (multiple loci)

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17
Q

Evolution within species and over shorter time scales is known as?

A
  • microevolution
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18
Q

Evolution across species and over longer time scales is known as?

A

macroevolution

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19
Q

What is the primary ingredient for evolutionary change?

A

intraspecific variation

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20
Q

Three non genetic forms of inheritance?

A
  • cultural
  • maternal effects
  • epigenetics
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21
Q

What is cultural inheritance?

A
  • cross generational similarity in non-genetic behavioral traits, based on processes such as non-random imitation
  • tool use in non humans
  • song learning in birds (language?)
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22
Q

What are maternal effects? (/ parental effects)

A
  • non genetic effect of a mother on the phenotype of her offspring due to factors such as cytoplasmic inheritance, transmission of symbionts from mother to offspring or provisioning.
  • hormonally mediated
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23
Q

What is epigenetic inheritance?

A
  • inherited changes in gene expression or phenotype that are not based on changes in DNA sequence
  • due to DNA methylation
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24
Q

What is an example of evolutionary trade offs?

A
  • offspring
  • generally either many small simple offspring or few larger offspring
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25
Q

Three approaches to determine ratios of inheritance -

A
  • experimental crosses
  • correlations among individuals of known relatedness
  • common garden experiment - controlled environment
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26
Q

What is a transition mutation?

A

when a purine is swapped for the other purine or a pyrimidine with a pyrimidine

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27
Q

What is a transversion mutation?

A

when a purine is switched for a pyrimidine

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28
Q

Define pleiotropy

A

a single mutation affecting multiple traits

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29
Q

____ is the source of all genetic variation

A

mutations

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30
Q

Mutations can only be inherited ___

A

if the trait itself is heritable, and when the change occurs beyond the germ line

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31
Q

Are mutations random or directed? Which experiment shows this?

A

Mutations are random - the Lederberg experiment demonstrates this- pencillin resistance was already present in certain groups of bacteria before being exposed to it

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32
Q

A _____ mutation has no effect on amino acid sequence, A _____ mutation results in amino acid substitution

A

synonymous, non-synonymous

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33
Q

Most mutations are ____ but the average effect is _____

A

neutral, deleterious

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34
Q

Are mutations random or do they arise in response to environmental challenges?

A

completely random, stochastic, not deterministic

35
Q

What is a back mutation?

A

reversion to a wild type allele

36
Q

Provide four possible ways to estimate mutation rates

A
  • screen offspring of genetically characterized parents over multiple generations
  • score mutations after several generations (must account for selection)
  • indirect comparison of number of fixed mutations across species (u = D/2t)
  • Direct comparison of DNA sequences
37
Q

Roughly, what is the average mutation rate per gamete per generation?

A

10^-6, 10^-5 mutations per gamete per generation

38
Q

The average new human contains roughly how many mutations?

A

~70 new mutations, 2.2 deleterious mutations, .02 beneficial mutations?

39
Q

The larger the _____ the higher the ____ _____

A

The larger the genome, the higher the mutation rate

(does not apply to viruses)

40
Q

Can mutation rates be subject to selection?

A

Yes, mutations in proofreading genes can make them better or worse, affecting general rates of mutations

41
Q

Define genotype frequency

A

proportion of individuals in a population that carry a specific genotype at one or more loci

42
Q

Define allele frequency

A

Proportion of gene copies in a population that are a given allele ( = probability of selecting this allele when a gene s taken randomly from the population

43
Q

Change in allele frequencies = ?

A

evoultion

44
Q

The average phenotypic effect of mutations is ____

A

deleterious (as an evolutionary consequence)

45
Q

Define population genetics

A

study of frequency of alleles in a population and the causes of variation in these frequencies

46
Q

What is the Hardy Weinberg principle?

A

In a population of randomly mating individuals allele frequencies are conserved and in equilibrium unless external forces act on them

47
Q

Define incomplete dominance?

A

Heterozygote is a blend of the dominant and recessive phenotypes

48
Q

Allele frequencies are _____ by genotype frequencies

A

are NOT influenced

49
Q

How many generations does it take to return to HWEQ?

A

1 generation (under simple traits that are not sex linked)

50
Q

What is the maximum frequency of heterozygotes in a population?

A

0.5

51
Q

Two implications of HWEQ

A
  • HWEQ is established after one generation of random mating
  • Following establishment of HWEQ, genotype and allele frequencies remain unchanged from generation to generation
52
Q

What are the assumptions necessary for HWEQ? (5)

A
  • Random mating
  • Population is infinite
  • Population is closed
  • No mutation
  • No selection
53
Q

Define genetic drift

A

Random changes in the allele frequencies in a population due to sampling error

54
Q

Is the effect of genetic drift stronger in smaller or larger populations?

A

smaller

55
Q

What is the average time to fixation of a newly arisen mutaton?

A

4N generations

56
Q

The probability that a population will become monomorphic for one allele is equal to ________________

A

the initial frequency of that allele

57
Q

Heterozygosity ___ as the frequency of one allele approaches 1?

A

declines - H = 2p(1-p) (((1-1 =0) so no 2pq

58
Q

6 influences on effective population size

A
  • variation in number of progeny
  • sex ratio
  • natural selection
  • cross generational inbreeding
  • fluctuations in population size (especially during founder effects)
  • type of mating system
59
Q

Define effective population size

A

number of individuals in an ideal population in which all adults produce equal number of gametes that produces the rate of genetic drift seen in the real population
- harem dominated mammals - some male gametes are not represented

60
Q

What is the relevant conclusion of the neutral theory of molecular evolution

A

Rates of neutral mutations in non coding alleles is the most common type of mutation - most mutations are synonymous
- says that on mutations that dont affect the phenotype - genetic drift is responsible for the changes
- looks at genes instead of phenotypes
- similar to genetic drift

61
Q

What is the inbreeding coefficient?

A

F - the probability that a random pair of gene copies, inherited by offspring from two parent is identical by descent

62
Q

What does inbreeding result in in terms of frequency of genotypes?

A

Inbreeding results in heterozygote deficiency

63
Q

What two factors make inbreeding have negative effects on the phenotype?

A
  • exposure of deleterious recessive alleles
  • loss of heterozygote advantage
64
Q

Define selection (again)

A

Differential fitness - survival / reproductive success - of classes of entities (individuals) that differ in one or more characteristics

65
Q

Evolution by natural selection occurs if (3)

A
  • individuals in a population of entities (organisms) display phenotypic variation
  • fitness differences correlate with phenotypic differences (selection)
  • correlation between parent + offspring (heritability)
66
Q

Can you have evolution without natural selection?

A

yes - genetic drift - what the neutral theory talks about, genetic drift alone will likely affect non phenotypically relevant genes- can act on things that impact the phenotype

67
Q

Define fitness

A

the success of an entity in producing representatives in subsequent generations ( a combination of survival and reproductive success )

68
Q

3 components to fitness?

A
  • probability of survival to reproductive age (and across multiple reproductive periods)
  • average number of offspring produced via female function
  • average number of offspring produced via male function
69
Q

Four different levels of selection?

A
  • Individual selection - non random differences among different phenotypes (or genotypes) within a population in their contribution to subsequent generations
  • Genic selection - single gene is the unit of selection, such that outcome is determined by fitness values assigned to different alleles
  • Group selection - differential rate of origination or extinction of whole populations (or species) on the basis of differences among them in one or more characteristics
  • Species selection - species with different characteristics increase by speciation or decrease by extinction in number at different rates
70
Q

Generally, what is the strongest level of selection?

A

individual over group selection

71
Q
A
72
Q

What did Carolus Linnaeus create?

A

Established the framework for modern taxonomy in systema naturae

73
Q

Who were Darwin’s three main influences?

A

Lamarck Lyell and Malthus

74
Q

What was Thomas Malthus doing?

A

Theories on eugenics ( he liked it)
Influence on darwin
Argued that selection pressure is competition for resources like food

75
Q

Who was Alfred Russel Wallace

A

Similar studies to Darwin - did not come from money like Darwin did
Wrote to Darwin in 1858 nd presented with him in the same year
Influenced by transmutation of species (Lamarck)

76
Q

When was The Origin of Species published?

A

November 1859

77
Q

Three conditions for evolution by natural selection

A

Phenotypic variation, heritability and effect on fitness

78
Q

What is this formula? pt=1/2N?

A

frequency of a newly arisen allele

79
Q

What is the formula = u0 x 2Ne?

A

number of new mutations that arise in a diploid organism where Ne is the neutral mutation rate

80
Q

What is the formula = 1/(2Ne)

A

probability that a mutation will be fixed by genetic drift

81
Q

Whst is the formula = (2Neu0) x (1/(2Ne)) = u0

A

number of neutral mutations that arise and will someday be fixed

82
Q

What is the alternate formula of frequency of heterozygotes that is used to calculate F?

A

F = 1- (H/H0)
- the actual frequency of heterozygotes over the frequency if the population was in HWEQ

83
Q

How do you do an indirect comparison of mutation rates?

A

U=D/2t where D is number of diff alleles and T is time since divergence

BIOL 302 - Evolution (6 decks)

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