Population genetics

Question 1

Define Dobzhansky’s definition of population geneticsE

Answer 1

Evolution is a change in the frequency of an allele within a gene pool

Question 2

What does population genetics do?

Answer 2

Examines phenomena such as adaptation, speciation, population subdivision, population structure

Changes in the relaitve abundance of traits in a population can be tied to changes in the relative abundance of the alleles that influence them

Question 3

What is a population?

Answer 3

A group of interbreeding individuals

Question 4

Define genotype and gene frequency

Answer 4

Genotype frequency = proportion of individuals with a given genotype

Allele frequency = proportion of alleles of a given type at a locus

Question 5

Describe mendelian genetics in populations

Answer 5

Population genetics theory states that allele frequencies in a population will remain constant unless acted upon by Non-mendelian processes

Question 6

Punnett square

Question 7

Describe the Hardy-Weinberg equilibrium

Answer 7

For a two-allele locus
P + q = 1
In offspring, the frequencies of alleles remain constant so
p2 + 2pq + q2 = 1

Question 8

What are the assumptions of the Hardy-weinberg equilibrium?

Answer 8

1. Organisms are diploid and sexual with mendelian segregation and discrete generations
2. Allele frequencies are the same in each sex
3. Mating occurs at random
4. Population is large, so no genetic drift
5. No gene flow
6. No mutation
7. No selection

Question 9

How does drift alter allele frequencies?

Answer 9

Random stochastic changes (often associated with small population sizes)

Question 10

Selection

Answer 10

Zygotes with specific allele to not survive

Question 11

Mutation/gene flow

Answer 11

Mutation or migration introduce a beneficial allele

Question 12

What did population genetics lead to?

Answer 12

Neo-darwinian evolution (the modern synthesis) - understanding the mechanisms of inheritence combined with the concept of natural selection.

Question 13

What are the applications of population genetics?

Answer 13

The study of naturally occuring genetic differences beween organisms - genetic variation/allele frequencies
Genetic variation is important because it is the raw material of evolution

Question 14

Name some genetic markers

Answer 14

Blood group, sequencing, mtDNA, RAPDs, SNPs, MHC, AFLPs, microsatellites, allozymes, nuclear DNA

Question 15

What are microsatellites?

Answer 15

From a family of highly variable DNA sequences, variable number tandem repeats
Specifically short blocks of bases repeated over and over again.

Have a high mutation rate. Often variable in size (highly polymorphic). Often assumed to be selectively neutral, so reflect demography and not selection.

Highly abundant and dispersed throughout the nuclear genome

Co-dominant

Question 16

Give a population genetics study

Answer 16

European flounder microsatellite analysed at 9 microsatellite markers (12 populations)

Genetic distance calculated based on differences in allele frequency. Population structure.

Heat shock protein also analysed.