Evolution

Question 1

What is the significance of the phrase “descent with modification”?

Answer 1

This was the phrase Darwin used to describe the phenomenon he studied before the term ‘evolution’ was used.

Question 2

Adaptive evolution is caused by…

Answer 2

Natural selection.

Question 3

Explain the progression of arguments that leads to the conclusion of evolution.

Answer 3

1. All species could have a ton of babies, but they don’t. 2. Individuals are all different, and some of their traits are heritable.
2. There is a struggle for resources between individuals of a population that leaves only certain ones alive to reproduce.
3. The ones that survived did because they were more fit to the place, so their babies will be more fit and also survive better.
4. These favourable traits will accumulate over generations.

Question 4

Evolution does not create new traits. What does it do?

Answer 4

It selects pre-existing ones.

Question 5

What is homology in terms of evolution?

Answer 5

Similarity resulting from common ancestry.

Question 6

What is comparative embryology?

Answer 6

A study that reveals homologies not visible in adult organisms. Example: human fetuses have gill slits and post-anal tails.

Question 7

What is convergent evolution?

Answer 7

That’s where two different species happen to evolve analogous features, not because they are related, but because both of their environments called for those features.

Question 8

What are examples of some of the evidence for evolution?

Answer 8

• Fossils showing transitional stages
• Homology between species
• Embryology
• Adaptation of viruses and bacteria over generations

Question 9

What is microevolution, as opposed to macroevolution?

Answer 9

Microevolution is a change in allele frequencies in a population over generations. Macroevolution is the idea that everything evolved from a common ancestor.

Question 10

What is the ‘raw material’ on which evolution acts?

Answer 10

Mutation and sexual reproduction, which produce the variations among individuals.

Question 11

What are discrete characteristics?

Answer 11

Characteristics that vary on an either-or basis.

Question 12

What are quantitative characteristics?

Answer 12

Characteristics that vary along a continuum.

Question 13

What is a gene pool?

Answer 13

All of the alleles for all loci in a population.

Question 14

What is the Hardy-Weinberg principle?

Answer 14

It states that frequencies of alleles and genotypes in a non-evolving population remain constant from generation to generation.

Question 15

To what does the term p^2 refer (in the Hardy-Weinberg equation)?

Answer 15

Homozygous dominant individuals.

Question 16

To what does the term q^2 refer (in the Hardy-Weinberg equation)?

Answer 16

Homozygous recessive individuals.

Question 17

To what does the term 2pq refer (in the Hardy-Weinberg equation)?

Answer 17

Heterozygous individuals.

Question 18

What are the five conditions for non-evolving populations?

Answer 18

• No mutations
• Random mating
• No natural selection
• Large population size
• No gene flow

Question 19

What are the factors in evolutionary change?

Answer 19

Natural selection, genetic drift, and gene flow.

Question 20

True or false: genetic drift occurs randomly, and gene flow occurs through movement of individuals of a population.

Answer 20

True. Drift is unpredictable, but flow is directional.

Question 21

Name the three types of natural selection.

Answer 21

Directional, disruptive, and stabilizing.

Question 22

Why does only natural selection, as opposed to genetic drift and gene flow, produce adaptive change?

Answer 22

Because it is the only one that depends on the survival and reproduction of fittest individuals. The other two are just about tracking where the genes go.