Population Genetics Of Adaptation I

Question 1

How does speciation come about?

Answer 1

Over time, natural selection results in populations becoming divergently adapted to different environment

Question 2

An example of speciation

Answer 2

Adaptive radiation (Darwin’s finches)

Question 3

What is natural selection?

Answer 3

The mechanism of evolution change in populations

Question 4

What did Mendel demonstrate?

Answer 4

Particulate inheritance

Question 5

What is a gene?

Answer 5

Unit of heritable material

Question 6

What is an allele?

Answer 6

Discrète variant state of a gene

Question 7

What is the Hardy-Weinberg Theorem?

Answer 7

A conceptual model of organisation of genetic variation

Question 8

What are the assumptions of the Hardy-Weinberg theorem?

Answer 8

• infinite population size
• random mating
• no difference in viability

Question 9

What is the multiplication rule?

Answer 9

The probability of two independent events both occurring is the product of the probability of each event occurring

Question 10

What is the addition rule?

Answer 10

The probability of any one of a set of mutually exclusive events occurring is the sum of the probabilities of the individual events

Question 11

Neutral modelling

Answer 11

Looking for what patterns we might expect when nothing interesting is going on

Question 12

What is genetic drift?

Answer 12

Stochastic changes in allele frequency due to chance

Question 13

What fundamental truth does drift rely on?

Answer 13

Populations are not infinite

Question 14

What does drift lead to?

Answer 14

• Stochastic changes in allele frequencies
• loss of genetic variation

Question 15

What is the relationship between drift strength and population size

Answer 15

As population size increases, strength of drift decr were

Question 16

Graphs demonstrating drift relationship to population size

Answer 16

• plotting allele frequency against number of generations
• as n increases, allele frequency maintains a more central position across generations - remains more constant

Question 17

Allele frequency as a measure of

Answer 17

Genetic variation

Question 18

Which allele frequency would indicate the highest genetic variation?

Answer 18

0.5

Question 19

Selection acts on

Answer 19

Phenotypes

Question 20

What does selection acting upon phenotypes result in

Answer 20

Changes in allele frequency

Question 21

W

Answer 21

Fitness

Question 22

Fitness definition (Hardy-Weinberg)

Answer 22

Relative reproductive rate of individual with a given genotype

Question 23

Selection coefficient

Answer 23

• s
• change in fitness associated with allele when homozygous

Question 24

If s>0, the allele is

Answer 24

Beneficial

Question 25

Is s<0, the allele is

Answer 25

Deleterious

Question 26

Dominance

Answer 26

- h - the extent to which the effect of an allele on fitness is masked when heterozygous

Question 27

When h=1

Answer 27

The allele is dominant

Question 28

When h=0

Answer 28

The allele is recessive

Question 29

What does change in allele frequency depend on?

Answer 29

- fitness of each genotype - average population fitness

Question 30

Why does dominance accelerate adaptation?

Answer 30

- rare mutations are almost never homozygous because of larger selective coefficients - dominance is rare

Question 31

Migration rate

Answer 31

- m - probability that allele foot arrives on island by migration

Question 32

P*

Answer 32

Average allele frequency on other islands

Question 33

Give the equation for the island model of structured populations

Answer 33

P2 = P1(1-m)+P*(m)

Question 34

What does migration prevent?

Answer 34

Divergence between populations

Question 35

Migration is essentially the phenotypic level of what genotypic process (my thoughts)

Answer 35

Gene flow

Question 36

If there is gene flow amoung populations,

Answer 36

They will all eventually reach the overall average allele frequency

Question 37

Relationship between gene flow and allele frequency

Answer 37

Plotting allele frequency (p), against number of generations, if gene flow (migration) is present, equilibrium frequency of 0.5 (p with a flat cap) will be reached after 42 generations

Question 38

How do migration, selection, and genetic drift affect genetic diversity?

Answer 38

Migration: increases diversity Selection: deterministic loss of low fitness allele Drift: stochastic loss of diversity by chance

Question 39

Genetic diversity

Answer 39

Provides the ‘fuel’ for adaption by natural selection

Question 40

Selective sweeps happen faster for allleles that are

Answer 40

- Codominant - h = 0.5

Question 41

Migration

Answer 41

Homogenises allele frequencies, while bringing genetic diversity back into populations

Question 42

Gene drift leads to the loss of

Answer 42

Rare alleles