Natural Selection

Question 1

One cause of genetic drift is ___, in which a small group of individuals leaves its home population and establishes a new, isolated settlement.

Answer 1

the founder effect

Question 2

Select all of the following that can lead to evolution in a population.

Answer 2

• mutation
• migration
• selection

Question 3

A ____ is a change in an organism’s DNA sequence and is the raw material for evolution, because genes affect the phenotypes and evolution acts on phenotypes.

Answer 3

mutation

Question 4

Reproductive success of an organism can also be referred to as

Answer 4

fitness

Question 5

When a population size drops rapidly over a short period, causing a loss of many alleles that were present in the larger ancestral population, this is referred to as the ____ effect.

Answer 5

bottleneck

Question 6

A change in allele frequencies hat occurs by chance and that tends to eliminate alleles in a population rather than increase diversity is called

Answer 6

genetic drift

Question 7

A mutation can affect evolution in a species only if

Answer 7

subsequent generations inherit it

Question 8

Rank the following from highest fitness at the top to lowest fitness at the bottom. (Assume that the numbers represent the entire lifetime of the mayfly mother.)

Answer 8

1. A mayfly that lays 400 eggs and mothers 3 offspring that survive to reproductive age
2. A mayfly that lays 800 eggs and mothers 2 offspring that survive to reproductive age
3. A mayfly that lays 900 eggs and mothers 1 offspring that survive to reproductive age
4. A mayfly that lays 1,000 eggs and mothers 0 offspring that survive to reproductive age

Question 9

Select all the examples of nonrandom mating.

Answer 9

• mating only within a specific group
• choosing mates based on certain characteristics
• mate choice based on social position

Question 10

When the intermediate phenotype of a trait is being selected for and the extreme phenotypes are being selected against, the population is probably undergoing

Answer 10

stabilizing selection

Question 11

A difference in the appearance between males and females of a species is called

Answer 11

sexual dimorphism

Question 12

Fitness depends on which of the following?

Answer 12

• number of successful reproductive efforts in lifetime
• proportion of offspring that survive to reproduce
• ability to survive long enough to successfully reproduce

Question 13

Natural selection requires

Answer 13

genetic diversity

Question 14

Select all the key properties of evolutionary adaptations

Answer 14

• they are heritable

- they can confer reproductive success

Question 15

When two phenotypic extremes of a trait are being selectively favored, then a natural population is undergoing ____ selection.

Answer 15

disruptive

Question 16

The ability of an organism to camouflage with its environment is an example of a(n)

Answer 16

adaptation

Question 17

Selection for dark-winged moths in a population of moths with pigmentation that varies from light to dark is an example of ___ selection.

Answer 17

directional

Question 18

Sexual selection is a special form of natural selection in which individuals vary in ability to

Answer 18

obtain mates

Question 19

Rank the following turtles from lowest fitness at the top to highest fitness at the bottom.

Answer 19

1. A turtle that dies at 100 years and fathers 0 surviving offspring
2. A turtle that dies at 75 years and fathers 10 surviving offspring
3. A turtle that dies at 50 years and fathers 20 surviving offspring
4. A turtle that dies at 20 years and fathers 30 surviving offspring

Question 20

Select all of the following that are examples of sexual selection.

Answer 20

• male to male combat during the mating season
• female birds choosing mates with the best nest-building skills
• males displaying showy plumage to females to get more opportunities to mate

Question 21

Select all of the following that are examples of the bottleneck effect.

Answer 21

• North American bison

- greater prairie chickens

Question 22

What is an example of the founder effect?

Answer 22

A few birds colonizing an isolated island

Question 23

What causes the movement of alleles between populations?

Answer 23

Migration

Question 24

Directional, disruptive, and stabilizing are all types of ____, in which certain phenotypes are favored over others.

Answer 24

natural selection

Question 25

Select all of the effects of migration.

Answer 25

- introduce new alleles into a population | - decreased regional differences in genetic diversity

Question 26

A chance change in a population's allele frequencies, such as after a drastic reduction in population size, is the root of what force of evolution?

Answer 26

genetic drift

Question 27

If a predator is more likely to prey upon fish that are brightest in color, then natural selection in this environment will favor

Answer 27

drabber fish

Question 28

Select the true statement about mutation and natural selection.

Answer 28

Natural selection acts on existing mutation.

Question 29

What is a mechanism by which harmful alleles can be maintained in a population even though homozygous recessive individuals have greatly reduced fitness?

Answer 29

heterozygotes have greater fitness

Question 30

Select all of the following that can limit the actions of natural selection.

Answer 30

- an organism's evolutionary history - traits that affect survival but not reproduction - disasters such as floods and volcanoes that eliminate allele combinations

Question 31

Select all the reasons why males usually show the greatest effects of sexual selection.

Answer 31

- Females have high investment in reproduction | - Males mush compete for access to females

Question 32

What genotype for the "sickle cell gene" causes mild symptoms of sickle cell disease but confers resistance to malaria?

Answer 32

heterozygous

Question 33

The goal of natural selection is to produce perfect organisms.

Answer 33

False

Question 34

Genetic drift has a greater effect on

Answer 34

small populations

Question 35

The diagram illustrates change in a bacteria population due to the presence of an antibiotic over many generations. This is an example of

Answer 35

natural selection

Question 36

If the environment changes, a trait that was adaptive may become nonadaptive or costly, demonstrating that

Answer 36

evolution continuously shapes populations

Question 37

A population of snails is separated when an eight-lane highway is built. After 50 years, the two separate populations can no longer interbreed. This describes the process of

Answer 37

new species forming

Question 38

The model that proposes that speciation occurs in brief bursts interrupted by long periods of little change is ____ equilibrium.

Answer 38

punctuated

Question 39

Select all of the following that are prevented by postzygotic reproductive barriers.

Answer 39

- production of fertile offspring | - survival of offspring to maturity

Question 40

Match the postzygotic reproductive barrier on the left with its example on the right.

Answer 40

- Hybrid inviability - Hybrid eucalyptus seeds do not germinate; seedlings die very early. - Hybrid infertility - The offspring of a lion-tiger mating (liger) is infertile. - Hybrid breakdown - Offspring of hybrid mosquitoes have abnormal genitalia.

Question 41

If a zygote cannot form between two organisms, then a type of ____ reproductive barrier is present.

Answer 41

prezygotic

Question 42

Organisms have changed over time; new species have appeared while other species have gone extinct. This is a description of ____.

Answer 42

macroevolution

Question 43

The ____ model of speciation proposes that evolution proceeds in small, incremental changes over many generations.

Answer 43

gradualism

Question 44

According to the biological species concept, a species is a population

Answer 44

whose members can interbreed and produce fertile offspring.

Question 45

What type of reproductive isolating barrier occurs after the formation of a zygote and reduces the fitness of a hybrid?

Answer 45

postzygotic

Question 46

Select all the examples of organisms from the fossil record that offer evidence of punctuated equilibrium.

Answer 46

- mammals - bryozoans - mollusks

Question 47

Match the type of prezygotic reproductive barrier on the left with its example on the right.

Answer 47

- Habitat isolation - Herbivores ladybird beetles feed on different types of plants. - Temporal isolation - Field crickets mature at different times. - Behavioral isolation - Frog mating calls differ.

Question 48

The formation of a new species is called

Answer 48

speciation

Question 49

Select all of the reasons why the biological species concept is not a perfect definition of a species.

Answer 49

- It doesn't apply to asexually reproducing organisms - It only accounts for absolute reproductive isolation - It is impossible to apply to extinct organisms known only from fossils

Question 50

Select the two models of speciation.

Answer 50

- gradualism | - punctuated equilibrium

Question 51

Match the name of the type of prezygotic reproductive barrier on the left with its description or an example on the right.

Answer 51

- Habitat isolation - populations live in different places - Behavioral isolation - a variation in a courtship ritual - Mechanical isolation - reproductive structures that do no fit together - Gametic isolation - sperm that does not fertilize the egg - Temporal isolation - active at different times of day

Question 52

Select all the postzygotic reproductive barriers.

Answer 52

- hybrid infertility - hybrid inviability - hybrid breakdown

Question 53

Over many hundreds of years, the definition of ____ has changed several times as scientists have refined ideas.

Answer 53

a species

Question 54

The figure labeled A represents ____, and the figure labeled B represents ____.

Answer 54

gradualism; punctuated equilibrium

Question 55

The speciation and extinction of the dinosaurs are examples of ____, and the increased frequency of a particular genotype that specifies a color patter in fish is an example of ____.

Answer 55

macroevolution; microevolution

Question 56

When two populations no longer share the same gene pool, then ____ has occurred.

Answer 56

speciation

Question 57

The accumulation of small changes in a population by microevolution can eventually lead to large-scale

Answer 57

macroevolution

Question 58

Mechanisms of ____ prevent successful reproduction and include prezygotic barriers and postzygotic barriers.

Answer 58

reproductive isolation

Question 59

Carolus Linnaeus classified species based upon ____ but not upon ____.

Answer 59

body structure; evolutionary relationships

Question 60

Select all the criteria biologists can use to define species.

Answer 60

- reproductive isolation | - DNA sequence analysis

Question 61

Select three ways that genetic divergence can occur between two separated populations.

Answer 61

- natural selection - genetic drift - mutation

Question 62

Select the most accurate statement about gradualism and the fossil record.

Answer 62

For organisms such as diatoms that existed in large, connected populations, the fossil record shows a slow pace of gradual changes.

Question 63

When might speciation occur rapidly? Select all that apply.

Answer 63

- After a key adaptation arises | - After a major environmental change wipes out many species

Question 64

What type of organisms appear to have evolved by gradualism, as suggested by the fossil record?

Answer 64

microscopic protists