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BIO220 > BIO220 Lecture 13 > Flashcards

BIO220 Lecture 13 Flashcards

Human-agricultural coevolution

1
Q

define: coevolution

A

reciprocal evolutionary responses in a pair of species, caused by selection imposed by each other

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2
Q

define: sexual coevolution

A

reciprocal evolutionary responses in the 2 sexes, caused by selection imposed by each other
- e.g. mate selection

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3
Q

human agricultural coevolution

A

reciprocal evolutionary responses in humans & their agricultural species, caused by selection imposed by each other

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4
Q

human agricultural coevolution is driven by…

A

culture

  • agriculture
  • husbandry
  • passed down from generation to generation through culture
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5
Q

in humans, __ can drive coevolutionary change

A

culture

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6
Q

evolution by natural selection is a ___ and ___ process

A

genetic & ecological

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7
Q

Why is evolution by natural selection a genetic & evolutionary process?

A
  • ecology provides selection

- genetics provide the material that is transmitted across generations

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8
Q

for humans, ecology includes…

A
  • culture

- organisms that we interact with

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9
Q

what is used to digest milk

A

lactase enzyme

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10
Q

what reaction does lactase catalyze?

A

lactose -> glucose + galactose

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11
Q

wild type for lactose digestion

A

lactose intolerant

- except people of N. Europe origin

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12
Q

Opposite of lactose intolerant

A

lactase persistence

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13
Q

which cultures that was studied showed lactase presistence?

A
  • N. Europeans (dairy farming)

- African cultures (mobile dairy farming)

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14
Q

Define: genetic drift

A

variation in the relative frequency of different genotypes in a small population

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15
Q

Why are small populations subject to genetic drift?

A

random sampling of genes

- such a small population size, so maybe only 1 individual has a trait, and they die

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16
Q

chance vs. determinism: genetic drift

A

chance

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17
Q

chance vs. determinism: natural selection

A

determinism

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18
Q

how do we tell if something is deterministic or due to chance?

A

if independent events have the same results over and over again, it’s probably deterministic

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19
Q

define: convergent evolution

A

independent evolution of the same trait in different groups (populations, species)

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20
Q

___ evolution provides evidence for natural selection

A

convergent

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21
Q

Does convergent evolution act on the same / different genes?

A

Open question, can be both

- lactase example was same gene

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22
Q

___ humans were unable to digest lactose as adults

A

Neolithic

23
Q

When did lactase persistence appear?

A

after the appearance of dairy agriculture

24
Q

In African cultures, mutations in lactase is associated with…

A

lactase persistence into adulthood

25
Q

example of convergent evolution

A

lactase persistence into adulthood

26
Q

How do we examine imprints that coevolution has left on human genomes?

A

apply principles of population genetics

27
Q

population genetics

A

compare patterns of genomic variation that is seen in current group vs. completely neutral model

28
Q

non-synonymous mutations

A

mutations that change AA

29
Q

synonymous mutations

A

mutations that do not change AA

30
Q

we would expect ___ genetic variability in the regions of the genome that experience more selection

A

less

31
Q

we would expect there to be ___ differentiation between populations at sites that experience more selection

A

more

32
Q

effect of neutral mutations on synonymous vs. non-synonymous mutations

A
  • protein function is not changed
  • same rate of synonymous and non-synonymous mutations
  • dN/dS = 1
33
Q

effect of deleterious mutations on synonymous vs. non-synonymous mutations

A
  • more mutations = lower fitness
  • synonymous mutations favoured
  • dN/dS < 1
34
Q

effect of beneficial mutations on synonymous vs. non-synonymous mutations

A
  • more mutations = higher fitness
  • non-synonymous mutations favoured
  • dN/dS > 1
35
Q

Approx ___ sites in a gene sequence are replacement sites

A

3/4

36
Q

how to predict DNA difference b/t species?

A
  1. Align gene sequence
  2. Evaluate dN/dS ratio

*3/4 are assumed to be synonymous mutations (estimate) - this makes calculations fair

37
Q

define: genetic hitchhiking

A

as beneficial mutations spread, they drag their nearby mutations along

38
Q

consequence of genetic hitchhiking

A

genetic variation in areas of beneficial mutation goes down

39
Q

what determines the region size that is affected by genetic hitchhiking?

A

rate of recombination

40
Q

what does recombination do to genetic hitchhiking?

A
  • breaks things up

- lots of recombination = small area where genetic diversity is low

41
Q

lactose persistence has higher / lower variability than lactose intolerance? Why?

A

lower; selected on by natural selection

42
Q

what has the evolution of lactose persistence done to cows?

A

select for milk production -> reduced genetic variation in the milk producing genes

43
Q

starch digestion

A

polysaccharides -[amylase]-> maltose -[maltase]-> glucose

44
Q

which gene encodes amylase enzyme? How many copies of it do we have?

A

AMY1

Many copies in the genome (2-12)

45
Q

More copies of AMY1 means…

A

more amylase can be made

46
Q

humans vary in the ___ of the AMY1 gene

A

number of copies

47
Q

in the AMY1 study, why can we eliminate environmental variability?

A

because we are looking at gene copy numberf

48
Q

In the amylase study: what is imposing selection on what?

A

Cultural behaviour (how much starch in diet) impose selection on humans (copies of AMY1 gene)

49
Q

Siberian Yakut have low / high starch diets

A

low

50
Q

AMY1 number should be the most different between which groups?

A

populations that eat low starch vs. populations that eat high starch

51
Q

diarrheal disease cause __% of deaths in children

A

15

52
Q

we use __ to scan the genome for regions responsible for co-adaption. What do we look for?

A

population genetic principles.
look for regions in the DNA where there is large similarity between populations. This is where natural selection forces have acted.

53
Q

What do we use genetic principles to do?

A

look for regions responsible for co-adaption in the genome.

BIO220 (24 decks)

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