Lecture 10: Mechanisms of Evolution

Question 1

What is Darwinian fitness?

Answer 1

Darwinian fitness is defined as the contribution that an individual makes to the gene pool of the next generation in comparaison to the contributions from other individuals. In other words, fitness is measured only in terms of the number of healthy offspring produced.

Question 2

What is the primary driving force of evolutionary change?

Answer 2

Natural selection

Question 3

What are the three mechanisms of evolution?

Answer 3

1. Genetic Drift
2. Gene Flow
3. Sexual Selection

Question 4

What is genetic drift?

Answer 4

Genetic drift is a change in a gene pool due to chance.

Question 5

What is the bottleneck effect?

Answer 5

A change in the gene pool due to a disaster such as an earthquake or flood that kills off most of a population size is called the bottleneck effect

Question 6

What is the founder effect?

Answer 6

When a few individuals from a population make it to a new and isolated habitat after a disaster, who will unlikely share a gene pool with the large population it came from is known as the founder effect.

Question 7

What is gene flow?

Answer 7

Individuals may migrate into or emigrate out of a population, which is called gene flow. It tends to make separate populations more genetically similar as they exchange genes.

Question 8

What is sexual selection?

Answer 8

Sexual selection is a form of natural selection whereby certain individuals are more likely to attract mates and, therefore, have more offspring.

Question 9

Which of the following are mechanisms of evolution? Select all that apply.
A) mutation
B) genetic drift
C) gene flow
D) selection (natural or sexual)

Answer 9

All of the above

Question 10

Consider this population of mice (all beige). Given the requirements for selection to occur, do you think that natural selection can occur in this population?
A) Yes!
B) No!

Answer 10

B) No!

Question 11

We learned about inheritance. When we say that a trait is heritable, what does this mean?
A) it is acquired during an individual’s lifetime because of their environment and is passed on to offspring from any cell of the body
B) it is encoded in DNA and passed on to offspring through germ cells
C) it is learned throughout an organism’s lifetime and taught to offspring by parents

Answer 11

B)

Question 12

If there is no antibiotic in our bacteria example, would selection still happen?
A) Yes!
B) No!

Answer 12

B) No!

Question 13

Consider our population of mice (5 GG mice, 4 CC mice, and 1 TT mouse). Which mechanism of evolution could have resulted in the TT mouse with the dark brown coat colour? Assume there are no other populations of mice in this example.
A) Mutation
B) Natural Selection
C) Gene Flow
D) Genetic Drift

Answer 13

B) Natural Selection

Question 14

There is another way that a dark brown mouse with a different version of the coat colour gene could show up in our population. Which of the explanations below best describes how this might happen?
A) natural selection creates a dark brown mouse
B) a dark brown mouse from a nearby population migrates into this population
C) sexual reproduction creates a new version of the coat colour gene

Answer 14

B)

Question 15

Your classmate is confused about the difference between gene flow (migration) and a founder effect (genetic drift). Briefly explain how you would clarify the difference between these two processes to your classmate.

Answer 15

Gene flow describes the migration or emigration of individuals in a population, making populations more genetically similar. A founder effect within genetic drift describes the establishment of a small population from a large population due to a drastic reduction in numbers