population genetics

Question 1

study of genetic variation in traits

Answer 1

quantitative genetics

Question 2

foundation of evolutionary genetics

Answer 2

population + quantitative genetics
variation due to evolutionary history (processes shape variation)
to understand we require mathematical models

Question 3

what creates variation at each locus

Answer 3

mutationw

Question 4

what shuffles combination across loci among individuals

Answer 4

recombination

Question 5

what is molecular genetic variation

Answer 5

varying DNA sequences among individuals

Question 6

alleles

Answer 6

alternative DNA sequences ta locus
sequence of DNA inherited as a unit

Question 7

loci

Answer 7

position in the genome of an allele

Question 8

what do population, quantitative and evolutionary genetics all rely on

Answer 8

understanding concept of alleles and allele frequencies

Question 9

SNP

Answer 9

single nucleotide polymorphism
(but sequences can differ in several ways or have complete structural differences)

Question 10

what creates phenotypic differences

Answer 10

sequence differences
allelic variation

Question 11

when all individuals have the same allele, a locus cannot contribute variation

Answer 11

only contributes when there are alternative alleles
depends on specific allelic variants at the locus

Question 12

can you describe effect of gene

Answer 12

no
we can only describe phenotypic differences associated with different versions of the gene

genes with different alleles leading to different phenotypes produce genetically based phenotypic variation

Question 13

how do allele frequencies relate to phenotypic variation

Answer 13

depends on frequencies of alleles

Question 14

frequency of A

Answer 14

number of A alleles/ total number of alleles

Question 15

frequency of a

Answer 15

number of a alleles/ total number of alleles

Question 16

how many alleles in a diploid population of N individuals

Answer 16

2N

Question 17

total number of A alleles in a diploid population

Answer 17

2x the number of AA homozygotes (nAA) + THE NUMBER OF Aa HETEROZYGOTES (nAa)

Question 18

so frequency of F(A)

Answer 18

2x(nAA) + (nAa)/ 2N= p
2x(naa) + (nAa)/ 2N=q

Question 19

why’s change in allele frequency important

Answer 19

tells us about evolutionary change

Question 20

how can population differences be used

Answer 20

to understand migration/ gene flow
different alleles favoured in different environments

Question 21

how do we measure genotype frequency

Answer 21

The proportion of a population with a given genotype.

Question 22

what is a hardy Weinberg model

Answer 22

A simple model where diploid individuals are constructed by randomly and independently sampling two alleles from an infinitely large pool of gametes.

Question 23

assumptions of hardy Weinberg model

Answer 23

• Population infinitely large
  
  • Random mating- all individuals have an equal chance of mating with each other
  • No migration in or out of the population
  • No selection*
    No mutation*

Question 24

population very large means

Answer 24

no sampling error
allele frequencies constant

Question 25

random mating means

Answer 25

all individuals equally as likely to mate with eachother no inbreeding, no outbreeding sampling of two alleles is independent

Question 26

no migration means

Answer 26

closed pop. alleles not influenced by variation from other populations entering

Question 27

no selection

Answer 27

genotypes have no effect on fitness all genotypes have same average survival and fecundity

Question 28

no mutations

Answer 28

no new alleles enter no current alleles removed

Question 29

why is HW idealised

Answer 29

assumptions always violated but pop is always close to HWE offers a null model, so we can ask why it is different, what rules were violated

Question 30

prediction of HWE

Answer 30

allele frequency do not change as long as pop. meets assumptions genetic frequencies are product of alleles frequencies and will return to these frequencies after a single generation of random mating

Question 31

what are alleles when they are rare

Answer 31

almost always heterozygotes mutations effect in heterozygote governs its initial fate (strongly impacts evolutionary processes)

Question 32

non random mating

Answer 32

some allele combinations will occur at higher frequencies than expected or at lower frequencies

Question 33

assortative mating

Answer 33

phenotype biased mating means frequencies of certain genotypes will be altered

Question 34

positive assortative mating

Answer 34

individuals with similar traits more likely to mate with eachother

Question 35

inbred

Answer 35

two alleles can be copies of the same allele in one of their ancestors, two alleles are IBD (from common ancestor)

Question 36

inbreeding

Answer 36

matings tend to be between relatives relatives more likely to share allele beyond expected random chance increased levels of homozygosity

Question 37

inbreeding coefficient f

Answer 37

probability that two alleles are IBD proportional reduction in heterozygosity compared to what is expected in HWE

Question 38

inbreeding depression

Answer 38

when inbreeding reduces viability or fecundity homozygotes have lower fitness (caused by deleterious recessive mutations) which are hidden in heterozygotes and cannot be removed

Question 39

genetic load

Answer 39

harboured deleterious recessive alleles across genome reflects mutation selection balance