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HELENP EE Evolution and Natural Selection > EE Lecture 4: Natural Selection > Flashcards

EE Lecture 4: Natural Selection Flashcards

1
Q

define adaptation

A

a characteristic that enhances survival or reproduction relative to alternative characters - often derived relative to the ancestral state and is the result of natural selection

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2
Q

what is a characteristic that enhances survival or reproduction relative to alternative characters called

A

an adaptation

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3
Q

what is fitness measured in

A

reproductive success

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4
Q

what is fitness a property of

A

genotypes, phenotypes or popns NOT individuals

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5
Q

what is fitness NOT a property of

A

fitness is not a property of individuals

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6
Q

define fitness

A

the average number of offspring that survive to reproductive age

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7
Q

what is the word eqtn for fitness

A

fitness = average fecundity x average survivorship

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8
Q

what does fitness describe

A

the growth rate of the popm

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9
Q

what is fecundity

A

actual reproductive rate of an org/popn

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10
Q

what is fecundity measured by

A

the number of gametes produced by an org

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11
Q

what two things are determined for fitness measurements

A
  1. fecundity

2. average survivorship

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12
Q

what does selection act on

A

phenotypes

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13
Q

what is selection caused by

A

environment

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14
Q

what does selection involve

A

non random survival and reproduction of phenotypes

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15
Q

what is the greatest fitness an org can reach? (in number)

A

1

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16
Q

give relative fitness of all possible alleles

A

WAA, Waa, WAa

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17
Q

how do you work out expected genotype frequencies for after selection

A

do genotype frequencies before selection then multiply by the relative fitness
eg. AA = p^2(WAA)

18
Q

what symbol is used to determine the relative fitness

A

W

19
Q

what does W mean

A

relative fitness

20
Q

what does wbar (W with bar on top) mean

A

popn average fitness

21
Q

draw eqtn linking relationship between allele and genotype frequencies after selection

A

p^2(WAA) + 2pq(WAa) + q^2(Waa) = w bar

22
Q

how do you work out pā€™ (new allele freq) after selection

A

pā€™ = [p^2(WAA) + pq(WAa)]/w bar

23
Q

which phenotype does selection favour

A

dominant phenotype

24
Q

which phenotype does stabilizing selection favour

A

intermediate

25
Q

discuss selection for vivax malaria resistance

A

Plasmodium vivax requires DARC protein on RBC to enter and infect cells - duffy null mutation results in loss of DARC expression - duffy null phenotype resistant to vivax malaria

26
Q

what protein does Plasmodium vivax require on RBC to enter and infect cell

A

DARC protein

27
Q

what does a duffy-null mutation result in the loss of

A

duffy null mutation results in the loss of DARC expression

28
Q

what is the result of the Duffy-null phenotype

A

vivax malaria resistance conferred from duffy-null phenotype

29
Q

what does MHC stand for

A

major histocompatability complex

30
Q

what is the MHC

A

set of cell surface molecules encoded by a large gene family which controls part of the immune system in vertebrates
it is the most polymorphic region known

31
Q

what is the most polymprphic region of genome known as

A

the MHC complex

32
Q

what is the MHC complex primarily involved in

A

immune system

33
Q

what is primarily involved in transplant rejection

A

the major histocompatability complex

34
Q

what is major function of MHC

A

bind to peptide fragments derived from pathogens

35
Q

what is balancing selection

A

multiple alleles are actively maintained in the gene pool f a pop at frequencies above that of gene muation
usually selects for heterozygotes

36
Q

what is purifying selection

A

negative selection

removal of deleterious mutations and can result in stabilising selection through the purging of deleterios variatoin

37
Q

what is stabilising selection

A

favours individuals with an intermediate phenotype

38
Q

what is disruptive selection

A

favours individuals at both extremes

39
Q

what is directional selection

A

favours individuals at one phenotypic extreme

40
Q

which selection maintains diversity

A

balancing selection

41
Q

when does selection change gene frequencies the fastest (wrt. alleles)

A

when alleles are at intermediate frequencies

HELENP EE Evolution and Natural Selection (14 decks)

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