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DISEASE E&E Final Exam > 19. Evolution and Ecology I > Flashcards

19. Evolution and Ecology I Flashcards

1
Q

Evolution:

A

-change in heritable characteristics of biological populations over successive generations

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2
Q

Evolutionary theory consists of:

A

-history
-mechanisms

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3
Q

Evolutionary tree of life:

A

-purposed by Darwin
-all organisms are related to each other via common descent
-evidence: put in groups based on shared morphological traits

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4
Q

Humans share common ancestor with:

A

-chimpanzees and other primates
-all mammals and vertebrates

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5
Q

Mechanisms of evolution:

A

-processes responsible for creating new species and diversity of life

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6
Q

Mechanism of evolution include:

A

-mutation
-natural selection
-genetic drift
-genetic exchange between populations

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7
Q

Darwin:

A

-“On the Origin of Species”
-mechanism of natural selection was controversial
>most accepted the idea of common descent and evolution as historical fact
-mechanism of heredity: solved by Gregor Mendel and others

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8
Q

For evolution by natural selection there needs to be:

A

-variation in phenotype

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9
Q

Variation in phenotype:

A

-some individuals are susceptible to infectious disease whereas others are resistant
>genes (ie. Alleles) coding for immunity that confer susceptibility or resistance to infectious disease
-heritable!

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10
Q

Evolution by natural selection example:

A

-fox that preys on mice with dark fu
>dark fur allele will decrease
*evolution is the change in allele frequency over time
*fox is the agent of natural selection

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11
Q

Evolution of mammals:

A

-18 placental orders (morphology and molecular biology)
>4 major clades

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12
Q

Whales:

A

-most closely related to carnivores, odd-toed ungulates, dolphins and bats

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13
Q

Rare genomic changes (RGCs) include:

A

-insertions
-deletions
-changes in gene order
-gene duplication
-etc.

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14
Q

RCGs:

A

-important in phylogenetic analysis of DNA sequence data
-rare
-excellent markers of common descent

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15
Q

Euarchontoglires and RCGs:

A

-primates
-rabbits and hares
-rodents
*share 18AA deletion in a specific gene

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16
Q

Afrotheria and RCGs:

A

-sea cow
-elephant
-hyrax
-aardvark
*share 9-bp deletion in BRCA1 gene

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17
Q

Parasites and natural selection:

A

-parasites can be a strong force of natural selection on their host
-Squirrelpox virus eradicated red squirrels in UK
-MYXV killed 500million rabbits in 2 years in Australia
-Bd reduced abundance of >500 amphibain species

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18
Q

Parasites have strong negative effects on host:

A

-survival
-reproduction

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19
Q

Selection for increased host resistance: experiment with fruit flies

A

-host: fruit fly
-parasite: parasitoid wasp
-wasps lay eggs inside fruit fly larvae
>hatches=kills larva
*fruit larva mount an encapsulation response that kills wasp egg
>only 5% have this response

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20
Q

Selection experiment: fruit flies

A

-selected fruit flies for a stronger encapsulation response over 8 generations
>exposed them to high densities of parasitoid wasps (natural selection)
*only survivors were allowed to mate and produce next generation
*protective immune response from 5% to 60%

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21
Q

Control line (no selection) fruit flies:

A

-did NOT evolve parasitoid resistance

22
Q

House finches and mycoplasmosis:

A

-house finches: native to western NA
>introduced to eastern NA and disease spread over 2 years
>western NA finches are disease-free

23
Q

Clinical signs and transmission of mycoplasmosis:

A

-ocular and nasal discharge
-crusts can damage cornea and lead to blindness
>death from starvation and predation
*direct transmission
*high virulence

24
Q

High virulence of M. gallispeticum:

A

-leads to strong selection for disease resistance in the eastern NA house finches

25
Q

Disease (myocoplasmosis) emergence associated with:

A

-60% decline in house finch population
*endemic in 20% house finch population

26
Q

Arizona (western NA) and Alabama (eastern NA) finches:

A

-eastern: 12 years of co-existence with disease
*abundance was higher in naïve western (Arizona) finches compared to Alabama
>compared gene expression of them both

27
Q

Gene comparison between Arizona and Alabama finches:

A

-infection changed expression of 52 genes
*16 associated with immunity
>compared expression of 16 genes in evolved and unevolved finch populations

28
Q

16 gene comparison of evolved and unevolved finch populations:

A

-infection reduces expression of immune genes in unevolved (Arizona) finches compared to evolved (Alabama) finches
*M. gallisepticum suppresses immunity!

29
Q

Eastern finches:

A

-have evolved resistance to the immune suppression

30
Q

Survival of finches:

A

-took M. gallispeticum from 5 different years
-adapted (Alabama) birds had higher survival compared to ancestral birds (for 3 of the last years)
*evolved resistance that enhanced their survival following infection over the years

31
Q

Evolution of resistance to mycoplasmosis in house finches:

A

*high virulence: strong selection for resistance to pathogen in eastern house finches
-eastern had lower abundance and enhanced expression of immune genes=higher survival
*evolved resistance in 12 years (evolution by natural selection is fast!)

32
Q

Malaria:

A

-mosquito-borne disease
-transmitted by females
-live in RBCs of vertebrate hosts
>feed on hemoglobin
-parasites burst out and invade new RBCs

33
Q

Malaria mortality:

A

-been around for 100,000 years
-300-700 million people infected each year
-kills 1 to 2 million people each year
-has exerted selection on human populations for a long time (ex. sickle cell trait)

34
Q

Sickle cell trait:

A

-caused by mutant version of human gene for hemoglobin
>HbS
-carriers are susceptible to malaria
-protects carrier against pathological effects of malaria

35
Q

RBCs carrying HbS:

A

-become ‘sickle-shaped’ in oxygen poor conditions

36
Q

Children with heterozygous HbA and HbS:

A

-incidence of malaria was reduced by 75%
-incidence of cerebral malaria was reduced by 86%
-incidence of sever malarial anemia was reduced by 90%
*sickle cell trait protects children against all types of malaria

37
Q

Malaria parasite density in blood:

A

-lower in children with AS compared to AA
-sickle cell trait controls malaria parasite density in blood
*lower parasite levels in AS reduce the severity of disease

38
Q

Distribution of sickle cell trait:

A

-congruent with distribution of malaria
-geographic association provides evidences that the trait has evolved to protect humans
*first example of human adaptation by natural selection

39
Q

Strong cost of malaria resistance:

A

-those with HbS have other problems
>pain
>RBCs can’t fit between blood vessels and ‘hits’ sides of vessels

40
Q

Artificial selection for productivity in farm animals: broilers

A

-increased weight
-broader breasts
-less feathers
-increased docility
-increased feed-to-meat ratio
*today: 2lbs of feed to 1lb of meat

41
Q

Growth-immunity trade-off in broilers:

A

-many studies found that faster growth decreases resistance/immune function

42
Q

Selection for milk yield in dairy cows:

A

-5000 (1960) to 11,000kg (2020)
-has also increased because of improvements in nutrition and management (not solely artificial selection)
>new technologies

43
Q

Mastitis in dairy cows:

A

-most common disease in dairy cattle in US and worldwide
>$1.7-2 billion lost each year
-inflammation of udder
-swelling, heat, redness, hardness or pain

44
Q

Increased milk yield selection and increased mastitis:

A

-increased mastitis in cows selected for high milk production and protein yield
-decreased mastitis in lines selected for low clinical mastitis
-no effect on mastitis on selection for low milk production
*selection for higher milk production makes cows more susceptible to clinical mastitis

45
Q

Artificial selection and inbreeding: causes

A

-intensive selective breeding for limited number of traits
-elimination of external environment
-adoption of same breeds worldwide
-globalization of breeding programs

46
Q

Population genetic diversity in dairy:

A

-important for long-term success of industry
-low genetic diversity=cannot respond to new pathogens or environmental pressures

47
Q

Artificial selection for productivity in farm animals:

A

-reduced disease resistance
>reduced genetic diversity
*high densities of animals as well

48
Q

Pathogens do very well in host populations with:

A

-high density
-poor immunity
-low genetic variation

49
Q

Intensive farming is highly dependent on:

A

-antibiotics
-vaccines
*overuse can cause other problems

50
Q

SUMMARY:

A

-parasites exert selection on hosts
-selection for productivity can compromise disease resistance (trade-off)
>broiler chickens and dairy cows
*evolution by natural and artificial selection can be very fast

DISEASE E&E Final Exam (11 decks)

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