BIO220 Lecture 13

Question 1

define: coevolution

Answer 1

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

Question 2

define: sexual coevolution

Answer 2

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

Question 3

human agricultural coevolution

Answer 3

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

Question 4

human agricultural coevolution is driven by…

Answer 4

culture

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

Question 5

in humans, __ can drive coevolutionary change

Answer 5

culture

Question 6

evolution by natural selection is a ___ and ___ process

Answer 6

genetic & ecological

Question 7

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

Answer 7

• ecology provides selection

- genetics provide the material that is transmitted across generations

Question 8

for humans, ecology includes…

Answer 8

• culture

- organisms that we interact with

Question 9

what is used to digest milk

Answer 9

lactase enzyme

Question 10

what reaction does lactase catalyze?

Answer 10

lactose -> glucose + galactose

Question 11

wild type for lactose digestion

Answer 11

lactose intolerant

- except people of N. Europe origin

Question 12

Opposite of lactose intolerant

Answer 12

lactase persistence

Question 13

which cultures that was studied showed lactase presistence?

Answer 13

• N. Europeans (dairy farming)

- African cultures (mobile dairy farming)

Question 14

Define: genetic drift

Answer 14

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

Question 15

Why are small populations subject to genetic drift?

Answer 15

random sampling of genes

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

Question 16

chance vs. determinism: genetic drift

Answer 16

chance

Question 17

chance vs. determinism: natural selection

Answer 17

determinism

Question 18

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

Answer 18

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

Question 19

define: convergent evolution

Answer 19

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

Question 20

___ evolution provides evidence for natural selection

Answer 20

convergent

Question 21

Does convergent evolution act on the same / different genes?

Answer 21

Open question, can be both

- lactase example was same gene

Question 22

___ humans were unable to digest lactose as adults

Answer 22

Neolithic

Question 23

When did lactase persistence appear?

Answer 23

after the appearance of dairy agriculture

Question 24

In African cultures, mutations in lactase is associated with…

Answer 24

lactase persistence into adulthood

Question 25

example of convergent evolution

Answer 25

lactase persistence into adulthood

Question 26

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

Answer 26

apply principles of population genetics

Question 27

population genetics

Answer 27

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

Question 28

non-synonymous mutations

Answer 28

mutations that change AA

Question 29

synonymous mutations

Answer 29

mutations that do not change AA

Question 30

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

Answer 30

less

Question 31

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

Answer 31

more

Question 32

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

Answer 32

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

Question 33

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

Answer 33

- more mutations = lower fitness - synonymous mutations favoured - dN/dS < 1

Question 34

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

Answer 34

- more mutations = higher fitness - non-synonymous mutations favoured - dN/dS > 1

Question 35

Approx ___ sites in a gene sequence are replacement sites

Answer 35

3/4

Question 36

how to predict DNA difference b/t species?

Answer 36

1. Align gene sequence 2. Evaluate dN/dS ratio *3/4 are assumed to be synonymous mutations (estimate) - this makes calculations fair

Question 37

define: genetic hitchhiking

Answer 37

as beneficial mutations spread, they drag their nearby mutations along

Question 38

consequence of genetic hitchhiking

Answer 38

genetic variation in areas of beneficial mutation goes down

Question 39

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

Answer 39

rate of recombination

Question 40

what does recombination do to genetic hitchhiking?

Answer 40

- breaks things up | - lots of recombination = small area where genetic diversity is low

Question 41

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

Answer 41

lower; selected on by natural selection

Question 42

what has the evolution of lactose persistence done to cows?

Answer 42

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

Question 43

starch digestion

Answer 43

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

Question 44

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

Answer 44

AMY1 | Many copies in the genome (2-12)

Question 45

More copies of AMY1 means...

Answer 45

more amylase can be made

Question 46

humans vary in the ___ of the AMY1 gene

Answer 46

number of copies

Question 47

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

Answer 47

because we are looking at gene copy numberf

Question 48

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

Answer 48

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

Question 49

Siberian Yakut have low / high starch diets

Answer 49

low

Question 50

AMY1 number should be the most different between which groups?

Answer 50

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

Question 51

diarrheal disease cause __% of deaths in children

Answer 51

15

Question 52

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

Answer 52

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

Question 53

What do we use genetic principles to do?

Answer 53

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