Lecture 53. Pop Genetics & Looking Ahead to Year 2

Question 1

What is a population?

Answer 1

A group of individuals of the same species that are able to interbreed

Question 2

What are sub-populations?

Answer 2

Where some species occupy a wide geographic range

Question 3

What is the purpose of population genetics?

Answer 3

To see genetic structure of a population (the number of alleles and frequency of each within a population (gene pool))
To see geographic patterns in distribution of allelic variation within and amongst sub-populations
To see temporal changes in genetic structure of a population

Question 4

What are the applications of population genetics?

Answer 4

Species conservation and utilisation of biodiversity
Essential for Genome-Wide Association Mapping (GWAM)

Question 5

What is the Hardy-Weinberg principle?

Answer 5

Method for investigating the movement of alleles in populations

Question 6

What is the Hardy-Weinberg principle essential for?

Answer 6

Understanding mechanisms of evolutionary change (e.g speciation)

Question 7

Using the Hardy-Weinberg principle, what are the starting parameters you must assume?

Answer 7

Infinitely large population
Random mating amongst individuals
No new mutations, migration or natural selection

Question 8

In the Hardy-Weinberg principle, what represent the frequency of the dominant allele?

Answer 8

p

Question 9

In the Hardy-Weinberg principle, what represent the frequency of the recessive allele?

Answer 9

q = (1-p)

Question 10

What is the total of genotype frequencies in the Hardy-Weinberg principle?

Answer 10

p² + 2pq + q² = 1

Question 11

What are the five things that can cause a change in genetic structure?

Answer 11

Mutation
Migration
Natural selection
Genetic drift
Non-random mating

Question 12

What are the three types of new alleles that mutations create?

Answer 12

Lethal, neutral and beneficial

Question 13

What is the ultimate source of all genetic variation?

Answer 13

Mutations

Question 14

How does migration cause a change in genetic structure?

Answer 14

New individuals move into a population, which introduces new alleles “gene flow”

Question 15

What is natural selection?

Answer 15

Differences in survival or reproduction which leased to adaptation
Differences in “fitness”

Question 16

What are the four types of natural selection?

Answer 16

Directional selection
Stabilising selection
Disruptive selection
Balancing selection

Question 17

What does directional selection favour?

Answer 17

Individuals at one extreme of a phenotypic distribution, which have greater reproductive success in a particular environment

Question 18

What does stabilising selection favour?

Answer 18

Survival of individuals with intermediate phenotypes
Extreme phenotypes are selected against

Question 19

What is an example of a stabilising selection factor?

Answer 19

Bird clutch size
Too many eggs and offspring die due to lack of care and food
Too few eggs does not contribute enough to next generation

Question 20

What does disruptive selection favour?

Answer 20

The survival of two or more different genotypes that each produce different phenotypes

Question 21

Where is disruptive selection likely to occur?

Answer 21

Populations that occupy diverse environments

Question 22

When does balancing selection occur?

Answer 22

When two or more alleles are kept in balance, and therefore are maintained in a population over many generations

Question 23

What symbol represents a heterozygote advantage?

Answer 23

Hˢ allele

Question 24

What is an example of balancing selection?

Answer 24

Sickle cell allele or malaria in Africa

Question 25

What is genetic drift?

Answer 25

Random loss of alleles from a population due to chance event(s)

Question 26

What populations are more stable, large or small?

Answer 26

Large

Question 27

What does genetic drift result in?

Answer 27

Loss of genetic variation

Question 28

What are genetic bottlenecks?

Answer 28

A sudden decrease in population size caused by adverse environmental factors

Question 29

What are founder effects?

Answer 29

Dispersal and migration that establish new populations with low genetic diversity

Question 30

What is assortative mating?

Answer 30

Individuals with similar phenotypes are more likely to mate
Increases the frequency of homozygotes

Question 31

What is disassortative mating?

Answer 31

Dissimilar phenotypes mate preferentially
Favors heterozygosity