Module 4 - Microevolution

Question 1

What are the two fundamental ideas in biology, and how are they explained?

Answer 1

Sameness & difference - sameness is explained by geneaology, while differences are explained by adaptation.

Question 2

What are Darwin’s 5 theories?

Answer 2

1. Perpetual change
2. Common decent
3. Multiplication of species
4. Gradualism
5. Natural selection

Question 3

What do the Hardy-Weinberg equations for genotypes and alleles represent?

Answer 3

Explains why the hereditary process does not change allele frequencies, or why the world is (or should be) stable.

Question 4

What are the assumptions made for the Hardy-Weinberg equations are applied?

Answer 4

• no mutation
• no immigration or emigration
• infinite population
• mating occurs at random
• no natural selection

if these are true then allele & genotype frequencies do not change across a generation, and the population is stable. If they are not, the opposite is true and populations will be unstable and evolving.

Question 5

What are four processes that upset Hardy-Weinberg equilibrium?

Answer 5

• random genetic drift
• nonrandom mating
• migration
• natural selection

Question 6

2pq is a measure of what?

Answer 6

Frequency of heterozygotes, or Aa.

Question 7

To find proportion of polymorphic genes, mean allele number or average heterozygosity, which equations can be used?

Answer 7

P = polyT/sample size
A = alleleT/sample size
Ho = heteroT/sample size

Question 8

What are the four major forces affecting genetic diversity?

Answer 8

1. Natural selection
2. Mutation
3. Gene flow
4. Genetic drift

Question 9

What is the neutrality hypothesis?

Answer 9

States that many mutations are not affected by natural selection and are maintained in the genome by genetic drift and migration alone.
k = u (for neutral sequences, rate of mutation u should equal rate of evolution k)

Question 10

What is the Bottleneck effect?

Answer 10

When a population descends from a small number of individuals that may have survived a particular generation. Effective population size Ne is reduced, this can lead to a loss of genetic diversity (the “bottleneck”).

Question 11

What are the components of the Extinction Vortex?

Answer 11

> small, fragmented & isolated populations (due to habitat loss, pollution, over exploitation, exotic species)
inbreeding, loss of genetic diversity
reduced adaptability for survival & reproduction
reduced effective population Ne

Question 12

There are ten small population effects. What are these?

Answer 12

1. Inbreeding depression - reduces fecundity and survival
2. Loss of genetic diversity - affects adaptability
3. Population fragmentation - reduced gene flow & its changing pathways within a structured population
4. Genetic drift - loss of genetic diversity.
5. Genetic load (purging) - accumulation and loss of mutations
6. Genetic adaptation to captivity - maintaining diversity within captivity
7. Resolving taxonomic uncertainties
8. Defining management units
9. Important characteristics
10. Forensic identification