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Summer Course II > Evolutionary Medicine > Flashcards

Evolutionary Medicine Flashcards

1
Q

What are the six reasons for vulnerability that arise due to the characteristics of natural selection? (6)

A
  1. Mismatch with modern environment
  2. Pathogens co-evolving with host
  3. Every trait is a trade-off
  4. Contrains on selection
  5. Selection maximizes reproduction (not health)
  6. Defences such as pain and fever are useful
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2
Q

What does the ‘reason for vulnerability’ “mismatch with modern environment” refer to?

A

Our bodies did not evolve to cope with novel environments. Selection and evolution to adapt to these new environments is slow.

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3
Q

What kind of diseases can often be explained by the fact that evolution is at a mismatch with the modern environment?

A

Chronic diseases

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4
Q

Pathogens frequently evolve [faster/slower] than their hosts

A

Faster
This allows pathogens to continuously stay infective to their host species

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5
Q

What allows pathogens to evolve faster than their hosts?

A

Pathogens frequently have a shorter reproductive cycle, allowing them to evolve faster

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6
Q

What is the evolutionary definition of ‘fitness’?

A

Reproductive success

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7
Q

What is the evolutionary defintion of reproductive success?

A

Number of offspring + whether they are fertile

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8
Q

What is a proximate explanation?

A

Mechanistic explanation: how does a trait work?

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9
Q

What is an ultimate explanation?

A

Evolutionary explanation -> how was a certain trait selected for = how does a trait increase fitness?

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10
Q

Why are diseases that occur at older are not/barely selected against?

A

They don’t impact the reproductive success of a species -> genes have already been passed on at that point

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11
Q

What is the primary force shaping the evolution of a species?

A

It’s environment

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12
Q

How many generations does it take for a new trait to establish?

A

~50-100 generations

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13
Q

Why can disease-causing genes sometimes persist?

A

Apparently they offer the species some sort of advantage when it comes to fitness, and therefore persist in the poulation

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14
Q

What are so-called neutral traits?

A

Variations that are not correlated with reproductive success

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15
Q

Which four major ways does the body have to deal with pathogens?

A
  1. Avoidance
  2. Resistance
  3. Immune tolerance
  4. Disease tolerance
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16
Q

What is immune avoidance? Name two examples.

A

Mechanisms preventing host exposure to microbes

  1. Anatomic barriers
  2. Particular behaviours
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17
Q

What is immune resistance?

A

General immune strategy, aimed at reducing or eliminating pathogens

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18
Q

What is immune tolerance?

A

Lack of response to an antigen

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19
Q

What is disease tolerance?

A

Balance between limitation of health/fitness due to the cost of infection vs. the worth of fighting off the disease

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20
Q

In which circumstances is disease tolerance favourable over immunity against a disease?

A

When fighting off the disease costs more energy and resources than the disease persisting

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21
Q

What is ‘adaptation’?

A

A trait that increases the ability of an individual to survive or reproduce, compared to individuals without a trait. Also: the process that produces that state.

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22
Q

What is ‘antagonistic pleitropy’?

A

One gene has positive effects on fitness through its impact on one trait, but negative effects on fitness through its impact on another trait.

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23
Q

What is ‘coevolution’?

A

Evolutionary changes in one thing (genes, sexes, species) induce evolutionary changes in another, and vice versa.

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24
Q

What is ‘Darwinian fitness’? (2)

A
  1. The extent to which an individual contributes genes to future generations
  2. An individual’s score on a measure of performance correlating with genetic contribution to future generations
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25
Q

What is ‘evolution’?

A

Changes in allele frequencies over time, and the phenotypic changes that result from that

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26
Q

What is ‘genetic drift’?

A

Random chance in allele frequencies due to chance factors

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27
Q

What is the ‘grandmother mypothesis of menopause’?

A

Menopause is a life history adaptation assocation with the contribution grandmother make to feeding their grandchildren

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28
Q

What is ‘kin selection’?

A

(Older) relatives promote the reproductive success of (younger) relatives

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29
Q

What is ‘natural selection’?

A

A non-zero correlation of trait variation with variation in reproductive success.

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30
Q

What is ‘neutral evolution’?

A

The change and occsasional fixation of alleles caused by the drift of alleles, that is not correlated wtih reproductive success.

31
Q

What is ‘path dependence’?

A

A certain body design has evolved along a gradual cumulative path, and there is no way back.

32
Q

What is ‘reproductive success’?

A

The number of viable, fertile offspring produced per lifetime.

33
Q

What is ‘sexual selection’?

A

The component of natural selection that is associated with success in mating

34
Q

What is the ‘theory of evolution by natural selection’?

A

The hypothesis that descent with mmodification is caused in large part by the action of natural selection

35
Q

What is the definition of ‘pathogenic bacteria’?

A

Bacteria that are capable of inflicting damage to their host

36
Q

The majority of prokaryotes that humans interact with [is/is not] pathogenic

A

Not pathogenic

37
Q

Which three classes of bacterial pathogens can be identified?

A
  1. Accidental pathogens
  2. Obligate pathogens
  3. Opportunistic pathogens
38
Q

What are accidental pathogens?

A

Bacteria that exist in the environment and occasionally infect humans. Infection of humans do not promote the spread of the pathogen to a new host.

39
Q

Where can accidental pathogens be found?

A

They exist in the environment as free-living bacteria or in assocation with other organisms

40
Q

Accidental pathogens are [less/more] heterogeneous than obligate pathogens

A

More heterogeneous

41
Q

What are examples of accidental pathogens? (3)

A
  1. Legionella pneumophila
  2. Bacillus anthracis
  3. Clostridium tetani
42
Q

What are obligate pathogens?

A

Those bacteria that must cause disease in order to be transmitted form one host to another, and that can solely grow an divide in association with their host

43
Q

Obligate pathogens [are/aren’t] capable of surviving in the environment

A

Obligate pathogens cannot survive in the environment

44
Q

What makes obligate pathogens dependent on their host?

A

They are highly dependent on their host, and obtain essential nutrients form their host

45
Q

What makes obligate pathogens dependent on their host for nutrients? Why is this trait an evolutionary advantage for these bacteria?

A

Lack several enzymes involved in energy metabolism

These enzymes are not encoded by the genome, resulting in a smaller genome that allows for quicker replication

46
Q

What are examples of obligate pathogens? (7)

A
  1. Mycobacterium tuberculosis
  2. Mycobacterium leprae
  3. Chlamydia trachomatis
  4. Rickettsia ricketsii
  5. Treponema pallidum
  6. Streptococcus pyogenes
  7. Yersinia pestis
47
Q

What are opportunistic pathogens?

A

Bacteria that can cause infections to humans when the immune system is not functioning property

48
Q

Opportunistic pathogens [can/can’t] be transmitted to the next host without causing disease

A

They can be transmitted without causing disease

49
Q

Where can opportunistic pathogens frequently be found?

A

Colonizing their host, but not causing infection

50
Q

What are examples of opportunistic pathogens? (3)

A
  1. Clostridium difficile
  2. Pseudomonas aeruginosa
  3. Staphylococcus aureus
51
Q

What are the steps of a prototypic bacterial infection? (5)

A
  1. Exposure
  2. Adherence
  3. Growth
  4. Invasion
  5. Toxicity & spread
52
Q

What are the three main ways in which humans come into contact with bacterial pathogen?

A
  1. Human-to-human
  2. Animal-to-human
  3. Environment-to-human
53
Q

What are the three ways in which humans get exposed to bacterial pathogens from animals?

A
  1. Direct contact with animals/droppings
  2. Consumption of contaminated animal products
  3. Vector mediated zoonoses
54
Q

What are the two ways in which bacteria can adhere to ECM?

A
  1. Specific
  2. Non-specific
55
Q

What is a common non-specific adherence mechanism of bacteria? Which two subtypes can be identified?

A

Polysaccharides, in:
1. Diffuse slime
2. Compact capsules

56
Q

What are two specific bacterial adherence mechanisms?

A
  1. Polysaccharides
  2. Proteins
57
Q

What is a common specific bacterial adherence mechanism using polysaccharides?

A

Teichoic acid

58
Q

What are three protein-based specific bacterial adherence-mechanism?

A
  1. Pili/fimbriae
  2. Lectins
  3. Microbial surface components recognizing adhesive matrix molecules (MSCRAMM)
59
Q

What is the main problem for bacteria while trying to grow?

A

Availability of nutrients

60
Q

Which nutrient is hard to access for bacteria that try to grow in humans? Why is this nutrient hard to access?

A

Iron -> sequestered within erythrocytes and bound with high affinity to hemoglobulin

61
Q

What are bacterial mechanisms to obtain iron? (3)

A
  1. Siderophores
  2. Membrane damaging molecules
  3. Enzymes
62
Q

What are siderophores?

A

Iron-chelating compounds

63
Q

What are the selective pressures on bacterial pathogens, causing them to evolve? (5)

A
  1. Defence systems of other micro-organisms
  2. Host defence systems
  3. Disinfection
  4. Vaccination
  5. Antimicrobial therapy
64
Q

Which traits are often encoded by the core genome of bacteria?

A

Genes that allow bacteria to survive and thrive in their respective niches

65
Q

What kind of microbes does the stomach select for?

A

Acid-resistant microbes

66
Q

What kind of microbes does the respiratory tract select for?

A

Aerobic microbes

67
Q

What kind of microbes does the (lower) intestinal tract select for?

A

Anaerobic/facultative aerobic bacteria

68
Q

What kind of microbes does the skin select for?

A

Drying-resistant bacteria

69
Q

Which traits are often encoded by mobile genetic elements of bacteria? (3)

A
  1. Toxins
  2. Capacities to deal with the innate immune system
  3. Capacities to deal with the adaptive immune system
70
Q

What are important bacterial capacities allowing them to deal with the innate immune system? (2)

A
  1. Innate immune evasion
  2. Survive phagocytosis
71
Q

What are important bacterial capacities to deal with the adaptive immune system? (5)

A
  1. Covering up in poorly immunogenic capsules
  2. Hiding in biofilms
  3. Producing proteases
  4. Spontaneous mutation & recombination
  5. Loss/obtaining of certain genes
72
Q

What are the bacterial mobile genetic elements?

A
  1. Plasmids
  2. Bacteriophages
  3. Transposons
  4. Insertion sequences
  5. Genomic islands
73
Q

What are the mechanisms that bacteria use to adapt to antimicrobial therapies? (3)

A
  1. Hiding in biofilms
  2. Spontaneous mutation/recombination
  3. Exhange of genetic materials

Summer Course II (4 decks)

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