Deck 16: How Populations Evolve

Question 1

In an equilibrium population

A) allele frequencies do not change.
B) natural selection occurs.
C) population size cannot change.
D) mutation rates do not change.
E) rates of gene flow are constant.

Answer 1

A

Question 2

A population carries two alleles for a trait in which T is dominant and t is recessive. In the Hardy-Weinberg equation, p2 represents the

A) proportion of homozygous dominant individuals.
B) decrease in heterozygous individuals.
C) proportion of homozygous recessive individuals.
D) increase in homozygous individuals.
E) proportion of heterozygous individuals.

Answer 2

A

Question 3

A population carries two alleles for a trait in which T is dominant and t is recessive. In the Hardy-Weinberg equation, q2 represents the

A) proportion of homozygous dominant individuals.
B) decrease in heterozygous individuals.
C) proportion of homozygous recessive individuals.
D) increase in homozygous individuals.
E) proportion of heterozygous individuals.

Answer 3

C

Question 4

The interaction of genes and environment produces a specific

A) gene pool.
B) population.
C) allele.
D) phenotype.
E) genotype.

Question 5

In a very small population of birds, assume 5 out of 20 alleles are the type that codes for blue feathers. What is the allele frequency of the ʺblue feather alleleʺ in this population?

A) 0.25
B) 0.50
C) 0.20
D) 0.40
E) 5

Question 6

Imagine that one of the original four mice that escape from a research lab is blind due to a genetic defect. If the escaped mouse breeds and most of the mice born in subsequent generations are blind from birth, this is most likely a case of

A) the founder effect.
B) artificial selection.
C) selective mutation.
D) natural selection.
E) an equilibrium population.

Question 7

Within a large population, if no mutations occur, no migration occurs, all matings are random, and each individual has an equal chance of reproducing, which of the following will probably happen?

A) A change in allele frequency will lead to rapid evolution.
B) Extinction will result.
C) Natural selection will occur at the normal rate for that species.
D) A bottleneck will occur.
E) No evolution will occur.

Question 8

A population is defined as

A) all individuals of all species located throughout the world.
B) all individuals of the same species located in a given geographic region.
C) those individuals of the same species that have an identical genetic makeup.
D) all individuals of the same species located throughout the world.
E) all individuals of all species located in a given country.

Question 9

Populations of organisms are constantly evolving, which means that they are always

A) at equilibrium.
B) getting bigger.
C) changing.
D) becoming more like humans.
E) improving.

Question 10

A young male baboon leaves the troop that he was born in and joins a small neighboring troop of small baboons. He quickly rises to become a dominant male. From an evolutionary point of view, what important process has occurred?

A) Gene flow
B) Nonrandom mating
C) Natural selection
D) Genetic drift
E) The bottleneck effect

Question 11

A population carries two alleles for a trait in which T is dominant and t is recessive. In the Hardy-Weinberg equation, 2pq represents the

A) proportion of homozygous dominant individuals.
B) decrease in heterozygous individuals.
C) proportion of homozygous recessive individuals.
D) increase in homozygous individuals.
E) proportion of heterozygous individuals.

Question 12

Inbreeding is defined as

A) sexual reproduction among closely related individuals.
B) sexual reproduction in a large population.
C) reproduction among unrelated individuals.
D) sexual population among unrelated individuals.
E) reproduction within a geographically isolated population.

Question 13

Which of the following can evolve?

A) Individuals
B) Populations
C) Communities
D) Genes

Question 14

In the context of evolution, equilibrium means

A) no individuals move into or out of the population.
B) equal numbers of males and females.
C) equal numbers of all alleles.
D) no change in allele frequency.
E) no change in population size.

Question 15

Which of the following can cause evolutionary change in a small population?

A) Lack of gene flow
B) All recessive alleles
C) Lack of mutations
D) Genetic drift
E) Homozygous individuals

Question 16

Which of the following is most likely to experience genetic drift?

A) A plant species that has spread to many different habitats all around the world
B) A population of common rodents that includes millions of individuals
C) A population of endangered birds that includes only five individuals
D) A species of insect that occurs all across North America
E) A population of bears that is growing by thousands of individuals each year

Question 17

The allele frequency of a population is the

A) number of all alleles in that population.
B) sum of all genes in that population.
C) relative proportion of a given allele in that population.
D) number of different types of alleles in that population.

Question 18

Evolution can be defined as

A) an individual changing into another species.
B) a change in the phenotype of an individual over his or her lifetime.
C) one species diverging into two species.
D) a change in the genetic makeup of an organism over time.
E) a change in the genetic makeup of a population over time.

Question 19

According to the Hardy-Weinberg principle, if 75% of the alleles in the gene pool are A1 and 25% are A2, what is the proportion of individuals with genotype A1A2 in this population?

A) 0.375
B) 0.5625
C) 0.0625
D) 0.025
E) 0.1875

Question 20

The gene pool for a particular population is made up of

A) all the alleles for a certain trait in a given individual.
B) all the genes for a certain trait that occur in the population.
C) all the genes that occur in the population.
D) the sum of all the homozygous individuals in the population.
E) the sum of all the heterozygous individuals in the population.

Question 21

Mutations

A) limit the potential for evolution.
B) arise due to environmental pressures.
C) can be helpful, neutral, or harmful to individuals.
D) are caused by natural selection.

Question 22

Gene flow

A) prevents migration of individuals into other populations.
B) negates the influence of evolution on a population.
C) limits evolutionary fitness.
D) can spread certain alleles throughout a species.
E) isolates populations from one another.

Question 23

Genetic drift results in a change in allele frequencies because

A) the population has not yet stabilized.
B) gene flow within the population allows alleles to flow between populations.
C) the population size is so small that chance occurrences can alter allele frequencies.
D) the population is so large that natural selection has little noticeable effect.

Question 24

Imagine a population of monkeys in South America whose habitat has been reduced to the point where only 20 individuals survive. This is an example of

A) a population bottleneck.
B) the founder effect.
C) natural selection.
D) sexual selection.
E) genetic drift.

Question 25

Which of the following can be measured to estimate an organismʹs evolutionary fitness?

A) The number of eggs it produces over its lifetime
B) The number of gametes it produces over its lifetime
C) The number of offspring it produces over its lifetime
D) The number of offspring it produces over its lifetime that survive to breed
E) The size of its offspring

Question 26

Male fish that display a bright blue color attract more mates as well as more predators. Maintaining that blue gene in the population is an example of

A) coevolution.
B) sexual selection.
C) the founder effect.
D) genetic drift.
E) a population bottleneck.

Question 27

Zoos often loan animals to other zoos for breeding purposes. From an evolutionary standpoint, what is the benefit?

A) It creates a bottleneck effect.
B) New animals increase zoo revenues.
C) It increases the rate of random mutations.
D) It increases the genetic diversity of the zooʹs population.
E) It increases the effects of natural selection on the population.

Question 28

Which of the following mutations would increase evolutionary fitness?

A) One that increases the frequency of successful reproduction
B) One that increases the life span of the organism
C) One that removes other alleles from the population
D) One that attracts more potential mates without increasing the frequency of reproduction
E) One that increases the birth weight of offspring while decreasing the number of offspring

Question 29

In general, each species of fruit fly in the Hawaiian archipelago is restricted to a single island. One hypothesis to explain this pattern is that new species formed after a small number of flies colonized each new island. This mechanism of speciation is called

A) artificial selection.
B) genetic equilibrium.
C) sexual selection.
D) the founder effect.
E) assortative mating.

Question 30

Evolution by genetic drift is most obvious in

A) small populations.
B) invertebrate species.
C) large populations.
D) aquatic organisms.
E) migratory species.

Question 31

Habitat loss, natural catastrophes, and/or excessive harvesting of a species often result in

A) artificial selection.
B) population bottlenecks.
C) increased fitness of individuals.
D) increased gene flow.
E) increased mutation rates.

Question 32

Having greater evolutionary fitness means

A) being better able to survive.
B) being larger or faster.
C) being able to produce more sperm or eggs.
D) having more offspring.
E) being stronger.

Question 33

The extreme loss of genetic diversity that has occurred in cheetah populations due to overhunting is the result of

A) a population bottleneck.
B) natural selection.
C) the founder effect.
D) genetic drift.
E) coevolution.

Question 34

Mutations are important because they

A) provide variation that can result in evolutionary change.
B) usually provide an individual with increased reproductive rates.
C) are always beneficial to the individuals affected by them.
D) occur in response to environmental demands.

Question 35

The 30,000 elephant seals alive today are genetically very similar due to

A) artificial selection.
B) random mutation.
C) the bottleneck effect.
D) natural selection.
E) the founder effect.

Question 36

Which of the following is an example of assortative mating?

A) A female sparrow chooses a mate because he attracts her by singing a different speciesʹ song.
B) A dominant male elephant mates with most females in a group, excluding other males from mating with the females.
C) A female lizard chooses to mate with the first male she encounters.
D) A female sheep chooses a mate because he has previously mated with many females.
E) A female mouse chooses a mate because he is the same color that she is.

Question 37

The Pennsylvania Amish have a very high frequency of an unusual allele that results in short arms and legs and extra fingers. This high frequency is thought to be the result of

A) the founder effect.
B) the addition of new members to an already established population.
C) nonrandom mutations.
D) coevolution.
E) a population bottleneck.

Question 38

A bacterial allele that provides resistance to the antibiotic streptomycin is

A) always beneficial to the bacterial cell.
B) beneficial to the cell in the presence of streptomycin.
C) beneficial to the cell in the presence of any antibiotic.
D) always detrimental to the cell.
E) neither beneficial nor detrimental to the cell.

Question 39

Shrews have been documented to travel across frozen lakes and establish populations on previously uninhabited islands. The low level of genetic diversity in the new populations is the result of

A) a population bottleneck.
B) assortative mating.
C) genetic drift.
D) coevolution.
E) the founder effect.

Question 40

The process by which allele frequencies are altered in a small population due to chance is called

A) random evolution.
B) fitness.
C) random mutation.
D) genetic drift.
E) assortative evolution.

Question 41

The type of selection most likely to act on a well-adapted population in a relatively constant environment is

A) directional.
B) disruptive.
C) stabilizing.
D) nonrandom.
E) artificial.

Question 42

A flock of birds with various beak sizes migrates to a new island where their traditional food is not available. However, there are plants that produce a variety of large nuts, which can be eaten by birds with the largest beaks, and plants that produce a variety of small, soft seeds, which can be eaten by birds with the smallest beaks. Over time, this population divides into two species with large and small beaks. This is an example of

A) directional selection.
B) stabilizing selection.
C) disruptive selection.
D) sexual selection.
E) genetic drift.

Question 43

Natural selection selects for or against certain

A) populations.
B) gene pools.
C) alleles.
D) phenotypes.
E) genotypes.

Question 44

A new predator is introduced to an area that can feed on any millipedes shorter than 200 millimeters. No millipedes that live in that area are longer than 15 millimeters. What will happen?

A) Disruptive selection will favor 15-millimeter-long millipedes.
B) Directional selection will favor predators that consume the smallest millipedes.
C) Millipedes will necessarily evolve to avoid the predator.
D) The millipedes will necessarily mutate to be longer.
E) All millipedes will be potential prey.

Question 45

The elaborate courtship displays common among animals are the result of

A) random mating.
B) sexual selection.
C) disruptive selection.
D) spontaneous mutations.
E) stabilizing selection.

Question 46

In a certain species of salmon, some adult males are extremely large whereas other adult males are very small, compared to the females. There are no intermediate-sized adult males in the population. This is probably the result of

A) disruptive selection.
B) artificial selection.
C) directional selection.
D) stabilizing selection.

Question 47

If the tallest and shortest individuals of a population of humans do not survive and reproduce as well as the individuals of ʺaverageʺ height, which type of selection would most likely result?

A) Directional selection
B) Artificial selection
C) Disruptive selection
D) Stabilizing selection

Question 48

When a species lives in a constant environment for a long time, the ʺaverage typeʺ of individual may have the best chance of surviving and producing the most offspring. What type of selection is occurring?

A) Sexual
B) Stabilizing
C) Artificial
D) Disruptive
E) Directional

Question 49

Which trait is the best example of an adaptation?

A) A mutation resulting in a heat-resistant enzyme in a bacterium living in a hot spring
B) A shorter neck in a giraffe that lives in an area with many rival males and tall trees
C) A longer tongue in an insect-eating mammal that feeds on insects that live in shallow burrows
D) A new mutation that confers Tay-Sachs disease in humans
E) A mutation resulting in weak branches in a species of tree that lives in windy regions

Question 50

Female finches, which do not sing, often choose to mate with males that sing a specific, elaborate song. This is an example of

A) inbreeding.
B) fitness.
C) sexual selection.
D) coevolution.
E) assortative mating.

Question 51

The male peacockʹs beautiful tail is really a trade-off between

A) sexual selection and natural selection.
B) disruptive selection and natural selection.
C) artificial selection and natural selection.
D) natural selection and genetic drift.

Question 52

In some butterfly populations, there are equal frequencies of alleles that code for black and yellow coloration. This is an example of

A) balanced polymorphism.
B) nonrandom mutations.
C) directional selection.
D) stabilizing selection.
E) sexual selection.

Question 53

Evolution by natural selection is

A) constantly occurring at the same rate in all organisms.
B) a rare event that has never been observed by scientists.
C) a process that has occurred only in the past.
D) currently occurring but only in scientific laboratories.
E) a process that occurs as a result of differences in fitness.

Question 54

In one butterfly species, the colors of individuals range from white to black, with many shades of gray in between. If the butterflies in a mountain population become more and more similar in color over several generations (e.g., if most butterflies are the same shade of gray), what kind of evolutionary force is likely acting on the population?

A) Artificial selection
B) Directional selection
C) Disruptive selection
D) Stabilizing selection

Question 55

The change in one population driven by a change in an associated population is called

A) fitness.
B) assortative evolution.
C) coevolution.
D) genetic drift.
E) random mutation.

Question 56

Members of one gender influence allele frequencies in a population by choosing mates according to some conspicuous feature in the other gender in the process called

A) genetic drift.
B) random evolution.
C) random mutation.
D) fitness.
E) sexual selection.

Question 57

A population of hummingbirds with a variety of beak sizes finds a new food source in a plant that has a long trumpet flower with nectar at the bottom of the trumpet. Over time, these hummingbirds develop longer beaks. This is an example of

A) directional selection.
B) stabilizing selection.
C) disruptive selection.
D) sexual selection.
E) genetic drift.

Question 58

Suppose a new mutation that improves metabolic efficiency is lost from a small population of mammals living in a region of seasonal food scarcity after a hurricane eliminates half the mammal population. This is an example of

A) directional selection.
B) stabilizing selection.
C) disruptive selection.
D) sexual selection.
E) genetic drift.

Question 59

If two or more phenotypes in a population are both favored by selection, what is happening?

A) Stabilizing selection
B) Sexual selection
C) Balanced polymorphism
D) Gene flow
E) Directional selection

Question 60

As predator and prey species acquire new adaptations to help them survive the constant ʺarms raceʺ between them, what evolutionary phenomenon is occurring?

A) Coevolution
B) Sexual selection
C) Artificial selection
D) Competition
E) Genetic drift

Question 61

Bright coloration in birds makes them stand out to predators. In female birds that sit on the nest, bright coloration is rare. This is likely the result of

A) artificial mutations.
B) gene flow.
C) natural selection.
D) coevolution.
E) stabilizing selection.

Question 62

Multidrug-resistant bacteria

A) have always been common in the natural environment.
B) have been eradicated worldwide.
C) are becoming less widespread.
D) are not serious threats to human health.
E) are becoming more widespread.

Question 63

The net migration of alleles into or out of a population from neighboring populations is called

A) gene flow.
B) genetic drift.
C) sexual selection.
D) stabilizing selection.
E) coevolution.

Question 64

The use of antibiotics caused the mutation that produced methicillin-resistant Staphylococcus aureus
(MRSA).

Question 65

In a population, the most common phenotype represents the dominant allele.

Question 66

When natural selection tends to split a population into two phenotypic groups, it is called

A) coevolution.
B) genetic drift.
C) stabilizing selection.
D) gene flow.
E) balanced polymorphism.

Question 67

The nonliving components of an environment, such as weather and water availability, are

A) biotic components.
B) abiotic components.
C) phenotypes.
D) genotypes.
E) alleles.

Question 68

Gene flow results when new individuals migrate into an area and join the breeding population there.

Question 69

The bright coloration of male birds is often the result of

A) gene flow.
B) genetic drift.
C) sexual selection.
D) stabilizing selection.
E) coevolution.

Question 70

Organisms that have the greatest reproductive success are considered the most evolutionarily fit.

Question 71

Imagine that a mutation for red eye color becomes very common in a population of flies because female flies in this population prefer to mate with red -eyed males. This is an example of

A) directional selection.
B) stabilizing selection.
C) disruptive selection.
D) sexual selection.
E) genetic drift.

Question 72

Which of the following can affect a small, endangered population so severely that it goes extinct?

A) Artificially adding new genes
B) Matings with a closely related species
C) Sexual selection
D) Increased mating opportunities
E) Lost alleles and/or low genetic diversity

Question 73

Natural selection causes genetic changes in populations.

Question 74

When one species evolves a new phenotypic feature and another species evolves new adaptations in response, it is called

A) gene flow.
B) genetic drift.
C) sexual selection.
D) stabilizing selection.
E) coevolution.

Question 75

Genetic drift is more common in large populations than in small populations.

Question 76

When different species closely interact for an extended period of time and develop new adaptations in response to each other, it is called

A) gene flow.
B) genetic drift.
C) sexual selection.
D) stabilizing selection.
E) coevolution.

Question 77

In a single family, the parents have brown eyes but all five of their children have green eyes. This is an example of evolution.

Question 78

Which of the following occurs due to chance events that change the allele frequencies in small populations?

A) Gene flow
B) Genetic drift
C) Sexual selection
D) Stabilizing selection
E) Coevolution

Question 79

Suppose a population of mostly sand-colored crabs migrates from a sand beach to a pebble beach and evolves a darker, speckled coloration that closely resembles the pebble beach. This is an example of

A) directional selection.
B) stabilizing selection.
C) disruptive selection.
D) sexual selection.
E) genetic drift.

Question 80

Which of the following phenomena favors individuals with average phenotypes over those with extreme phenotypes?

A) Gene flow
B) Genetic drift
C) Sexual selection
D) Stabilizing selection
E) Coevolution