Variation & Evolution

Question 1

What are the three conditions needed for Natural Selection:

Answer 1

1) Variation in traits

2) Heritability

3) Survivorship/Competition

Question 2

What is discrete Variation?

Answer 2

limited number of types (such as blood types)

Question 3

What is continuous Variation?

Answer 3

Having a multitude of variants (e.g., colour bands in the snail)

Question 4

What does fitness refer to?

Answer 4

the number of offspring an individual produces that survive to reproduce themselves

Question 5

Natural selection will not take place if…?

Answer 5

There is no variation

E.g., No humans have gills, so we cannot select for
them, regardless of how beneficial they might be

If the gene is not heritable

E.g., Working out and getting a strong heart might
make you live longer and have more children but
selection can not act upon it if is not a genetic trait

If there is no difference in survivorship or
reproductive ability between variants

E.g., Having attached or free earlobes doesn’t really
matter

Question 6

What are the Characteristics of Natural Selection

Answer 6

Dependent on the variation present in the population

Short-sighted – acts only present selection pressures

Question 7

What are some sources of variation?

Answer 7

Gene flow: immigration

recombination

ultimately, from mutation

Question 8

What are exampled of things that can cause mutations?

Answer 8

Radiation

certain chemicals
(e.g. carcinogens)

Question 9

What are the three kinds of natural selection?

Answer 9

Directional selection

Stabilizing selection

Disruptive selection

Question 10

What is random drift?

Answer 10

Chance events can still make these traits show change over time