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3s1: Evolution of health and disease > Week 3 > Flashcards

Week 3 Flashcards

1
Q

What are examples of rapid changes in the human environment causing mismathces with genetics?

A

Diet
Lifestyle
Infectious diseases
Climate change

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2
Q

What is the relationshup between daily energy expenditure?

A

Its decreasing
Early homo sapiens - 2,880 kCal
Kung hunter gatherer tribe - 2,178 M or 1,770 F
Sedentary modern humans - 2,000 M or 1,679 F
With odern humans losing 300 Kcal for activity compared to 1,284 with early homo sapiens

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3
Q

What is the differences in diets between ancestral hunter gathers and modern humans?

A

Modern eating more caloric dense diets
More carbs in modern humans
More fibre in early humans
More micornutrients in ancestral humans
Substatially more cereal grains in modern humans

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4
Q

Why are diet mismatches important for human health?

A

Metabolic syndromes (obesity and diabetes)
Ageing
Cancer

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5
Q

What is the relationship between humans and cancer?

A

Predisposition to cancer in humans byproduct of natural selection

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6
Q

Why is there higher rates of cancer in humans?

A

Lack of adaptation to:
Recent changes in environments (sanitised)
Recent changes in risk factors (diet, exercise)

Side effects of:
Selection for specific features of reproductive processes and life histories
Non seasonal oestrus

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7
Q

What is the hygiene hypothesises?

A

Lack of adaptation to modern ‘cleaner’ environments (‘hygiene hypothesis’)
In our evolutionary history, frequent exposure to infection at early age which primes immune system

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8
Q

What diseases could be explained by the hygiene hypothesis?

A

Allergies
Autoimmune diseases (type 1 diabetes)
Childhood leukaemia

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9
Q

What evidence is there for the hygiene hypothesis?

A

Allergies, Autoimmune diseases,Childhood leukaemia associated with highly active immune and cytokine alleles

Disease may be a side effect (‘overshoot’) - positive selection of those alleles in context of high prevalence of infection in recent human history

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10
Q

How has human reproduction impacted cancer rates in modern humans?

A

Selection for specific features of reproductive processes and life histories

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11
Q

What unique human attributes have led to increased cancer rates?

A

Non-seasonal oestrus
Cyclical mammary gland priming

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12
Q

What are the advantages of non seasonal oestrus?

A

Increase reproductive capacity (once we could protect ourselves from the environment)

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13
Q

What environment was non seasonal oestrus selected?

A

Pregnancies early, spaced and repeated
Protracted breastfeeding
Hunter gatherer-type diet

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14
Q

What in the modern environment may have caused problems for cancer and women cancer?

A

Women in modern / affluent societies
Don’t have same reproductive, breast feeding, diets or exercise patterns

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15
Q

What problems does the modern society mean for womens cancer rates?

A

Elevated exposure to oestrogens
Persistent, cyclical stress to mammary / ovarian stem cells
Exacerbated by diet / exercise habits
Fuels cell proliferation

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16
Q

What can happen if an envrionment/lifestyle changes?

A

Adapt through phenotypic plasticity and genetic adaptation e.g lactose tolerance
Migrate
Die

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17
Q

How has climate change impacted mortality?

A

Increased mortality arising from extreme weather
Thermal stress - heat waves, increased respiratory disease - high ozone
‘Event’ associated disease – e.g. cholera

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18
Q

How has climate change impacted disease vectors?

A

Change in distribution of disease vectors
Emerging diseases

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19
Q

How has climate change impacted food?

A

Increased variability in food and water supplies
Increased malnutrition

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20
Q

What could be the adverse and beneficial effects of temperature extremes?

A

Adverse - more daily deaths and disease events due to hot days
Beneficial - Reduced winter deaths and disease in some temperate countries

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21
Q

What could be the adverse and beneficial effects of regional crop yields?

A

Adverse - Reductions in many low-latitude and low rainfall regions
Beneficial effects - Increases in currently too cold regions

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22
Q

What could be the adverse and beneficial effects of climate change impacting water-borne diseases?

A

Adverse - Cholera risk might be amplified by coastal water warming and local flooding
Beneficial effect - Less risk where heavy rainfall diminished

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23
Q

What could be the adverse and beneficial effects of aero-allergen production?

A

Adverse - Increased allergic disorders (hay fever and asthama) due to longer pollen season
Beneficial - Reduced exposure to aero-allergens in some regions due to lesser production or shorter season of pollen circulation

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24
Q

How will climate change impact Aegis aegyptii in Australia?

A

Global warming increase territorial range of mosquito increasing the number of people effected by diseases spread by it ie Dengue fever

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25
Q

How is human health impacted by extreme heat events?

A

In 10 days in 2007, Athens experienced extreme heat events >45˚C.
Physiological responses to heat stress
Effectiveness of responses is limited
Increase in deaths and admissions for heatstroke during heatwaves

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26
Q

What is the predicted model for heat related deaths in the future?

A

Increase in the number of ehat related deaths in 2050 compared to 2005
Decrease in cold related deaths but not as many as lost due to heat

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27
Q

What are genetic adaptations to climate change?

A

Sweat responses
Volume /surface area
Evolution in stress response genes
Evolution in heat stress genes?

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28
Q

What is the problem with adaptations to climate change?

A

Likely too slow to counter rapid environmental change

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29
Q

How will migration increased in response to climate change?

A

IPCC reports - sea level rise
Spread of uninhabitable areas
Displacements predicted by climate change

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30
Q

What is the limits of migration for climate change?

A

There is only a limit to how many and where they can move to
For some animals there is many areas they can migrate too or cant move quick enough

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31
Q

What is an overview of Jared Diamond’s Collapse?

A

Describes how civilisations ended due to increased per head human impact on environment (overpopulation, deforestation and overhunting) mixing with climate change

32
Q

What is an example of climate change + human environmental impact causing civilisation collapse?

A

Easter island population: Settles around 1000 years ago
Population was around 3,000 at peak and within a hundred years was around a couple hundred

33
Q

What is ageing?

A

Ageing (or senescence) is a reduction in vital rates (age-specific survival and fertility)

34
Q

What is ageing physiologically?

A

Ageing (or senescence) is a physiological deterioration of an organism resulting in a decline in probability of survival and reproductive performance with advancing age

35
Q

What is the historical belief of ageing?

A

Historically, scientists thought that ageing affects humans and livestock but does not affect wild animals in natural environments

36
Q

What was the belief of Medawar on ageing in wild animals?

A

Whether animals can, or cannot, reveal an innate deterioration is almost literally a domestic problem; the fact is that under the exactions of natural life they do not do so. They simply do not live that long.

37
Q

Do all organisms age?

A

Ageing ubiquitous in nature and most animals do age

38
Q

What is the exmaple of wolves ageing?

A

Wolves hunt elk
Old wolves have lower killings and sucesses than in their prime compared to young inexperinced wolves

39
Q

What is senescence shown across wild animals?

A

Reviewing studies of wild animals, we find evidence for senescence in 175 species across 340 studies

40
Q

What are long lived organisms that age slower than expect?

A

Ocean Quahog (clam) 507 years
Three-toed box turtle 65 years
Rockfish 100-200 years

41
Q

Are Hydras truely immortal?

A

Ergo, Hydra may be seen as a pool of three stem cell lineages rather than an organism

42
Q

Why are Hydra believed to be immortal?

A

Hydrashows no signs of senescence in laboratory conditions

43
Q

Why is hydra immortality questioned?

A

Nevertheless, within-cell repair is imperfect and cannot solely protect against damage accumulation
Cellular damage drift leads to accumulation of damaged cell lineages, hence senescence

44
Q

What is the mechanism for hydra immortality?

A

High prevalence and continued division ofHydra׳s three stem cell lineages act against damage drift
Asymmetrical damage transmission during cell division – like bacteria
Germline is not segregated from the soma

45
Q

Is jellyfish Turritopsis ssp. immortal?

A

When starved, heat-shocked or injured, goes back to the previous developmental stage, a polyp, which then produces a new adult form (a medusa)
This cycle can be repeated several times

46
Q

What is the overview of the ageing of Trogoderna glabrum?

A

Small pest beetle Trogoderna glabrum
Larvae can partially reverse development in the absence of food
This cycle can be repeated several times

47
Q

Why arent Trogoderna glabrum?

A

However, after several cycles the ability to regrow diminishes and repeatedly reversed beetles show physiological deterioration
Time to regrowth increased from 9 days to 28 days in the fourth cycle
In other words, they do not escape ageing

48
Q

What is the mortality between Turtles, baboon and bogs?

A

Baboons and dogs have a lower natural hazard at early years but increase at a quickier rate than turtles

49
Q

What are the ultimate theories of ageing?

A

Weismann’s group selection theory
Medewar’s mutation accumulation
Williams antagonistic pleiotropy

50
Q

What are the proximate theories of ageing?

A

Hayflick’s limit
Rate of living and mitochondrial theory of ageing
Reactiove Oxygen Species damage
Telomeres
Disposable soma
Developmental theory of ageing

51
Q

What is an overview of telemere shortening theory of ageing?

A

Telomeres are protective caps on end of DNA
Telomerase is active in germline cells but is tightly repressed in normal somatic cells
Lack of telomerase causes cells to lose telomeres with cell division and senescence or cell death
Telomerase is reactivated is most cancers

52
Q

What is an overview of Weismann group selection theory?

A

When regulating duration of life, the advantage of the species and not the individual is alone of any importance.
Weismann suggested that long life after reproduction is unnecessary

53
Q

What are the problems ith Weismann’s arguement?

A

Naive group-selectionism - Gene-level selection > group level selection

Circular reasoning - Soma is perishable and vulnerable so nature made no effort to endow this part of individual with a life of unlimited length

54
Q

What did Weismann change his theory to for ageing?

A

Weismann abandoned his ‘group selection’ stance and
focused on the segregation between the germline and the soma – his main and long-standing contribution to our understanding of ageing

55
Q

What is the germ line and soma relationship?

A

Immortal cell lineage of germ plasm can develop into mortal cell lineage during embryo or adult life

56
Q

What is the overview of evolutionary ageing declines with age?

A

Haldane, 1941 – Huntington’s disease, caused by a dominant allele with high penetrance
rather common – too common?
Age of onset – 35.5 years

57
Q

What are the possible pathways for natural selection with age?

A

Mutation accumulation (MA) Medawar 1952
Antagonistic pleiotropy (AP) Williams 1957

58
Q

What is the definition of mutation accumulation?

A

Accumulation of alleles with late-acting deleterious effects due to weakening of selection late in life

59
Q

What is the definition of antagonistic pleiotropy?

A

Trade-off between early and late life fitness

59
Q

What is shadow selection?

A

Selection cannot “see” deleterious mutations whose effects are confined to late ages

59
Q

What is a within species comparison of death rates impacting senescence?

A

Compared two populations of wild North American opposums that lived on the main land and on the island – 1989 - 2009
Mainland – many predators
Island – no predators
Isolation – 4000-5000 years
Opposums on island live longer, age slower and have smaller litters

59
Q

How does flying impact ageing?

A

Flight is protection against predation that will lead to evolution of longer intrinsic lifespans and slower ageing

60
Q

How does death rates impact senescence?

A

“Low adult death rates should be associated with low rates of senescence, and high adult death rates with high rates of senescence.” - Williams 1957

61
Q

What is the difference between bird and mammal ageing?

A

Birds live longer than terrestrial mammals accounting for body mass
Bats live as long or longer than birds

62
Q

How did they prove that birds live longer than mammals?

A

de Magalhães, Costa compared mass of mammal and birds compared natural log of maximum longevity
Birds were shown to have live longer compared to similar sizes mammals

63
Q

What is the relationship between body size and lifespan?

A

The general trend is that the bigger the body mass the longer the lifespan

64
Q

What is the relationship between terrestrial and arboreal mammals?

A

Arboreal mammals live longer than terrestrial mammals due to trees having fewer predators and more escape oppotunities

65
Q

What is an experimental evolution of lifespan in Drosophila?

A

High mortality group had a higher mortality rate due to age
Low mortality group had a lower mortality rate due to age

66
Q

What are the two types of mutation accumulation?

A

Mutation accumulation - neutral in early life but failure rate increases over time
Positive pleiotropy - Negative throughout life but the failure rate increase with age

67
Q

What is an exmaple of postive pleiotropic mutation accumulation?

A

20 random mutations in Drosophila - Brengdahl 2020
16 reduce fitness overall
14 reduce fitness more in late-life
13 reduce fitness in early-life but more so in late-life

68
Q

How did they test for antagonistic pleiotropy?

A

50 generations of selection - Drosophila Melangaster
“base” lines and old lines

69
Q

What is the results for the antagonistic pleiotropy for drosophlia melanogaster?

A

For both male and female flies form the old lines lived longer but at the cost of reduced fecundity (prodiced fewer eggs)

70
Q

What is the overview of age-1 Caenorhabditis elegans?

A

Age-1 (+)(N2 Bristol) - All dead by day 25 but on day 2 produced 120 eggs a day
Age-1 (hx546)(TJ1052) - All dead by day 40 but on day 2 produced 90 eggs a day

71
Q

What is the relationship between anatagonistic pleiotropy and mutation accumulation?

A

They are not mutually exclusive!!
Perhaps more direct evidence for AP

Other key arguments for predominant role of AP are:
phenotypic plasticity
major effect genes

72
Q

What are the two theories for antagonistic pleitropy?

A

Resource allocation and Early life inertia

73
Q

What is an overview of resource allocation?

A

Disposable soma”; Reduced risk of early-life mortality
Insufficient resources –> Insufficient repair

74
Q

What is an overview of early-life intertia?

A

Developmental/programmatic theories of ageing; Hyperfunction
Insufficient selection –> Insufficient regulation

3s1: Evolution of health and disease (10 decks)

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