Unit 7, Topic 4

Question 1

A change in a gene or chromosome.

Answer 1

Mutation

Question 2

A group of individuals that belong to the same species and live in the same area

Answer 2

population

Question 3

Combined genetic information of all the members of a particular population

Answer 3

gene pool

Question 4

refers to an allele for which all members of a population are homozygous

Answer 4

fixed

Question 5

A change in the gene pool of a population due to chance

Answer 5

genetic drift

Question 6

Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population.

Answer 6

bottleneck effect

Question 7

Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population.

Answer 7

founder effect

Question 8

movement of alleles from one population to another

Answer 8

gene flow

ie: migration

Question 9

Form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve

Answer 9

directional selection

Question 10

Natural selection that favors intermediate variants by acting against extreme phenotypes

Answer 10

stabilizing selection

ie: the peppered moth

Question 11

favors individuals at both extremes of the phenotypic range

Answer 11

disruptive selection

Question 12

when individuals select mates based on heritable traits

Answer 12

sexual selection

Question 13

What factors contribute to phenotypic variation in a population?

Answer 13

Mutations, genetic drift, migration/gene flow, natural selection

Question 14

What does the phrase “non-selective pressures” mean?

Answer 14

Natural disasters (floods, famine, fires, hurricanes) and human activity like hunting

This is directly linked to the bottleneck effect.

Question 15

Why is genetic variation important to survival?

Answer 15

It allows natural selection to increase or decrease frequency of alleles already in the population; enables some individuals to adapt to the environment while maintaining the survival of the population.

Question 16

Research the bottleneck effect on cheetahs.
a. What has happened to their population?
b. How has this affected their genetic diversity?
c. If a new disease were to be introduced into the
cheetah population, what effect could it have? Why?
Be specific.

Answer 16

In this bottleneck the cheetahs of North America and Europe went extinct, leaving extant only the species’ Asian and African populations b. As large mammals died out across the world, the number of surviving cheetahs dwindled, which caused extreme inbreeding. c. The cheetah species is more likely to become extinct because alleles would begin to die out allowing few to survive.

Question 17

True or false: mutations can lead to new alleles.

Answer 17

true

Question 18

How is sexual selection similar to directional selection?

Answer 18

The response to sexual selection will depend on genetic variation in trait expression, more precisely on how much genetic variation there is in the direction of selection. The less the genetic variation aligns with the direction of sexual selection, the higher the genetic constraints for trait evolution