Mutations, Genetic Drift and Molecular Evolution

Question 1

What are the results of migration?

Answer 1

movement of individuals causing gene flow. reduces genetic variation. can be maladaptive

Question 2

what are the results of mutation?

Answer 2

increases genetic variation. very rare but is the source of new alleles.

Question 3

what are the results of genetic drift?

Answer 3

large effect in small population. allele frequencies can go up or down by chance

Question 4

what is a bottleneck?

Answer 4

sharp reduction in population size, extreme form of genetic drift

Question 5

what is the founder effect?

Answer 5

when a few individuals start a new population - can lose genetic variation

Question 6

what is non-random mating?

Answer 6

individuals choose a partner can increase/decrease certain phenotypes

Question 7

what are the results of inbreeding?

Answer 7

increases frequency of homozygotes, this can lead to deleterious recessive mutation and inbreeding depression

Question 8

what are the 3 fates of a mutation?

Answer 8

fixation, maintained, eliminated

Question 9

how are species genetically isolated?

Answer 9

mutations can arise and get fixed in different species

Question 10

what is genetic divergence?

Answer 10

how long a species has been genetically isolated

Question 11

what is the molecular clock?

Answer 11

correlation of time and genetic divergence

Question 12

how can the rate of the molecular clock vary?

Answer 12

attributed to intensity of selection. rates can vary from gene to gene

Question 13

what is genetic drift?

Answer 13

change of allele frequencies by chance

Question 14

what can be the result of genetic drift in small populations?

Answer 14

can prevent natural selection

Question 15

what is Ne?

Answer 15

effective population size

Question 16

what is effective population size?

Answer 16

size of an idealized population with the same genetic properties as observed in the real population

Question 17

what are the properties of an idealized population?

Answer 17

• equal reproducing sex ratio
• low variance in family size
• constant population size over generations

Question 18

why might the effective population size be smaller than the census?

Answer 18

number of males and females reproducing may differ eg a small of males could be reproducing as compared to females

Question 19

why would there still be an unequal contribution of genetics?

Answer 19

even with a 1:1 sex ratio some individuals will have more offspring than others

Question 20

when is genetic drift stronger?

Answer 20

• bottleneck is severe

- bottleneck is protracted

Question 21

why is genetic variation important?

Answer 21

fuel for evolution

Question 22

what are some types of mutation?

Answer 22

single base pair changes. substitution. point mutation. insertions/deletions - indels. gene duplication. slippage. chromosomal mutations

Question 23

what are SNPs?

Answer 23

when a single nucleotide base changes to a different base

Question 24

what is the role of a triplet?

Answer 24

codes for amino acids

Question 25

what a synonymous mutations?

Answer 25

change in DNA but no change of amino acid. silent.

Question 26

what are non-synonymous mutations?

Answer 26

causes a change in the amino acid coded for

Question 27

how is an SNP represented in an alignment?

Answer 27

where there is a different letter

Question 28

how is an indel mutation represented in an alignment?

Answer 28

by lines

Question 29

how is a slippage mutation represented in an alignment?

Answer 29

a simple repeating pattern is change

Question 30

what is a slippage mutation?

Answer 30

in a repetition pattern the polymerase can slip resulting in addition or subtraction`

Question 31

what are the outcomes of gene duplication?

Answer 31

• retain original function
• become pseudogenes (inactive)
• mutate (gain new function)

Question 32

what are the different types of chromosomal mutations?

Answer 32

paracentric inversion. reciprocal translocation. fusion. fission.

Question 33

what do fusion and fission mutations change?

Answer 33

the chromosomal number

Question 34

what are the different types of polyploidy?

Answer 34

autopolyploidy and allopolyploidy

Question 35

where does molecular evolution occur?

Answer 35

at the DNA

Question 36

what is positive selection?

Answer 36

new mutation = advantageous. increases in frequency. substitutes old form

Question 37

what is negative selection?

Answer 37

disadvantageous mutation is eradicated

Question 38

what is a neutral mutation?

Answer 38

determined by genetic drift. frequency of mutation rises and falls.

Question 39

what is the neutral theory?

Answer 39

• majority of mutations have no effect on fitness

- genetic drift not natural selection drives molecular evolution

Question 40

what are the predictions from neutral theory?

Answer 40

• molecular clock

- rate of substituion

Question 41

what is the molecular clock?

Answer 41

• genes evolve at a constant rate.

- genetic divergence proportional to divergence time

Question 42

what are the different hypothesis

Answer 42

1. generation time hypothesis
2. metabolic rate hypothesis
3. DNA repair efficiency hypothesis

Question 43

what is rate of substitution in neutral theory?

Answer 43

less constrained –> evolve more quickly. more constrained –> more deleterious.