EE Lecture 4: Natural Selection

Question 1

define adaptation

Answer 1

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

Question 2

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

Answer 2

an adaptation

Question 3

what is fitness measured in

Answer 3

reproductive success

Question 4

what is fitness a property of

Answer 4

genotypes, phenotypes or popns NOT individuals

Question 5

what is fitness NOT a property of

Answer 5

fitness is not a property of individuals

Question 6

define fitness

Answer 6

the average number of offspring that survive to reproductive age

Question 7

what is the word eqtn for fitness

Answer 7

fitness = average fecundity x average survivorship

Question 8

what does fitness describe

Answer 8

the growth rate of the popm

Question 9

what is fecundity

Answer 9

actual reproductive rate of an org/popn

Question 10

what is fecundity measured by

Answer 10

the number of gametes produced by an org

Question 11

what two things are determined for fitness measurements

Answer 11

1. fecundity

2. average survivorship

Question 12

what does selection act on

Answer 12

phenotypes

Question 13

what is selection caused by

Answer 13

environment

Question 14

what does selection involve

Answer 14

non random survival and reproduction of phenotypes

Question 15

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

Answer 15

1

Question 16

give relative fitness of all possible alleles

Answer 16

WAA, Waa, WAa

Question 17

how do you work out expected genotype frequencies for after selection

Answer 17

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

Question 18

what symbol is used to determine the relative fitness

Answer 18

W

Question 19

what does W mean

Answer 19

relative fitness

Question 20

what does wbar (W with bar on top) mean

Answer 20

popn average fitness

Question 21

draw eqtn linking relationship between allele and genotype frequencies after selection

Answer 21

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

Question 22

how do you work out p’ (new allele freq) after selection

Answer 22

p’ = [p^2(WAA) + pq(WAa)]/w bar

Question 23

which phenotype does selection favour

Answer 23

dominant phenotype

Question 24

which phenotype does stabilizing selection favour

Answer 24

intermediate

Question 25

discuss selection for vivax malaria resistance

Answer 25

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

Question 26

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

Answer 26

DARC protein

Question 27

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

Answer 27

duffy null mutation results in the loss of DARC expression

Question 28

what is the result of the Duffy-null phenotype

Answer 28

vivax malaria resistance conferred from duffy-null phenotype

Question 29

what does MHC stand for

Answer 29

major histocompatability complex

Question 30

what is the MHC

Answer 30

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

Question 31

what is the most polymprphic region of genome known as

Answer 31

the MHC complex

Question 32

what is the MHC complex primarily involved in

Answer 32

immune system

Question 33

what is primarily involved in transplant rejection

Answer 33

the major histocompatability complex

Question 34

what is major function of MHC

Answer 34

bind to peptide fragments derived from pathogens

Question 35

what is balancing selection

Answer 35

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

Question 36

what is purifying selection

Answer 36

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

Question 37

what is stabilising selection

Answer 37

favours individuals with an intermediate phenotype

Question 38

what is disruptive selection

Answer 38

favours individuals at both extremes

Question 39

what is directional selection

Answer 39

favours individuals at one phenotypic extreme

Question 40

which selection maintains diversity

Answer 40

balancing selection

Question 41

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

Answer 41

when alleles are at intermediate frequencies