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HELENP EE Evolution and Natural Selection > EE Lecture 5: Phenotype and Genotype > Flashcards

EE Lecture 5: Phenotype and Genotype Flashcards

1
Q

what is a haplotype

A

an association of different alleles on a chromosome - likely to be inherited together

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2
Q

what is a haplogroup

A

closely related haplotypes (non identical sequences)

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3
Q

what is a closely related set of non identical sequences called

A

a haplogroup

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4
Q

what is an assoiation of different alleles on a chromosome likely to be inherited together called

A

haplotype

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5
Q

how can you confirm a haplogroup

A

by doing a single nucleotide polymorphism SNP test

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6
Q

what are the most commonly studied haplogroups in humans

A

Y-DNA

mtDNA

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7
Q

how do Y-DNA and mtDNA change

A

NOT RECOMBINATION

only change by a chance mutation at each generation with no intermixture between parents’ genetic material

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8
Q

what is linkage equilibrium a property of

A

haplotypes not genotypes

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9
Q

what is linkage equilibrium

A

when 2 genes/traits/loci are inherited completely independently in each generation

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10
Q

what is the term for when 2 genes/traits/loci are inherited completely independently in each gen

A

linkage eqbm

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11
Q

what is the term for populations where combos of alleles/genotypes can be found in expected proportions

A

they are in linkage eqbm

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12
Q

at what level of linkage diseqbm does linkage eqbm occur

A

linkage eqbm occurs when linkage diseqbm = 0

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13
Q

what is linkage diseqbm (wrt. polymorphism)

A

it is the correlation ebtween polymorphisms

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14
Q

what is linkage diseqbm influenced by

A 
genetic linkage
selection
rate of recombination
rate of mutation
genetic drift
non random mating
popn structure eg. pop bottleneck
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15
Q

what is the mutation drift eqbm

A

rate of mutation is balanced by rate of genetic flow

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16
Q

what is the amount of genetic variation a function of

A

Ne and mu

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17
Q

what does the mutation drift eqbm suggest about alleles

A

theyre uncorrelated due to recombination

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18
Q

what is the null hypothesis used when testing for selection

A

that alleles are uncorrelated due to recombination

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19
Q

what does selective sweep allow for

A

rapid adaptation

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20
Q

what is selective sweep

A

the reduction or elimination of variation among the nucleotides in neighbouring DNA of a mutation, as a result of recent and strong positive natural selection

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21
Q

when can selective sweep occur

A

can occur when a new mtation occurs that increases the fitness of the carrier

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22
Q

what is selective sweep measured through

A

linkage disequilibrium eg. whether a given haplotype is overpresentted in a pop

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23
Q

what does strong linkage diseqbm indicate

A

recent selective sweep (due to recombination)

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24
Q

what does natural selection cause

A

loss of genetic diversity around the selected site
incresed LD around the selected site
an excess of the most common allele
deficiencyu of intermediate frequency alleles
LD decays with time since selection began

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25
Q

how does natural selection affect LD (linkage diseqbm)

A

increased LD around the selected site

LD decays with time since selection began

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26
Q

broadly describe what trait development is a result of

A

trait development = enviro and genotype = phenotype

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27
Q

how many years ago did selection begin

A

5000 yrs ago

28
Q

how is trait variation apportioned

A

Vp=Ve+Vg

29
Q

what does Vp = ?

A

VP=Ve +Vg

30
Q

what does Vp stand for

A

phenotypic variation in the pop

31
Q

what does Ve stand for

A

environmental variance

32
Q

what does Vg stand for

A

genetic variation

33
Q

what is apportionment for quantitative traits

A

Va=Vg

Va=additive genetic variance, depends on magnitude of effects of alleles and allele frequency

34
Q

what is symbol for additive genetic variance

A

Va

35
Q

what does additive genetic variance depend on

A

magnitude of effect of alleles and allele frequency

36
Q

what is Va for a single locus with 2 allele

A

Va = 2pqa^2

37
Q

what does 2pqa^2 equal

A

Va for a single lous with two alleles

38
Q

what is Va for multiple loci

A

Va=2∑piqiai^2

39
Q

what is a

A

the additive effect of an allele

40
Q

what does 2∑piqiai^2 equal

A

Va for multiple loci

41
Q

when inheritance is purely additive, where does the heterozygote lie

A

at mid point between homozygotes

42
Q

what does the phenotypic variation between each genotype represent

A

environmental variance Ve

43
Q

define heritability in terms of variation

A

the proportion of variation that is explained by genetics

44
Q

what is the proportion of variation that is explained by genetics

A

heritability

45
Q

how can heritability be estimated

A

as the correlation etween the mean of the parents and offspring

46
Q

what is the result of low correlation between the mean of the parents and offspring on heritability

A

low correlation = low heritability

47
Q

give equation for heritability

A

h^2 = Va/Vp

48
Q

what does Va/Vp equal

A

h^2 (heritability)

49
Q

what does R stand for

A

response to selection

50
Q

what is Response to selection

A

difference in means between parents and offspring

51
Q

what is S -what does it stand for

A

selection differential

difference in means between pops and the selected parents

52
Q

what is the difference in means between parents and offspring called

A

response to selection R

53
Q

what is the difference in means between pops and the selected parents

A

selection differential S

54
Q

with axis of midparent on X and offspring mean on Y, which axis does S correlate to

A

difference in X axis = S

55
Q

with axis of midparent on X and offspring mean on Y, which axis does R correlate to

A

difference in Y axis = R

56
Q

when correlation between parental and F1 phenotypes is high, what does this suggest about heritability

A

heritability is high

57
Q

what size is R when heritability is lower

A

R is small

58
Q

when heritability is high and the selection differential is high, what value is R

A

R is large

59
Q

give an example of human niche construction and covergent evoln

A

the evoln of lactase persistance in humans

60
Q

what is niche construction

A

the process by which orgs construct important components of their local enviro in ways that introduce novcl selection pressures

61
Q

discuss the evoln of lactase persistance

A

humans usually stop producing lactase after adolescence
most adults are lactose intolerant
there have been 5 lactase persistance mutations around the world
LP trait frequency is found in c.35% of adults but variance in continents

62
Q

when do humans usually stop producing lactase

A

after adolescence

63
Q

how many lactase persistance mutations have there been

A

5
c.Europe = 7500YA
3 in sub saharan Africa 7000YA
at least one in Middle East and N.Africa 8-10kYA

64
Q

when and were the lactase persistance mutations around the world

A

c. Europe 7500YA
3 in sub Saharan Africa 7000YA
one in Middle East and North Africa 8-10KYA

65
Q

what is % LP trait frequency

A

35%

66
Q

what are the advantages of being LP lactose persistant

A

milk good source protein/fat

strong selective pressures could have just been episodic eg. drought

HELENP EE Evolution and Natural Selection (14 decks)

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