Deck 16: How Populations Evolve

Question 1

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

Answer 1

D

Question 2

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

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

Answer 3

E

Question 4

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.

Question 5

Evolution can be defined as

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

Question 6

Inbreeding is defined as

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

Question 7

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

Question 8

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

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

Question 9

In the context of evolution, equilibrium means

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

Question 10

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

Question 11

A population is defined as

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

Question 12

Which of the following can evolve?

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

Question 13

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

Question 14

The allele frequency of a population is the

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

Question 15

In an equilibrium population

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

Question 16

The gene pool for a particular population is made up of

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

Question 17

The interaction of genes and environment produces a specific

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

Question 18

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 "blue feather allele" in this population?

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

Question 19

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.

Question 20

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

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

Question 21

Having greater evolutionary fitness means

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

Question 22

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

Question 23

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

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

Question 24

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) neither beneficial nor detrimental to the cell.
D) always detrimental to the cell.
E) beneficial to the cell in the presence of any antibiotic.

Question 25

Gene flow

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

Question 26

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

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

Question 27

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

Question 28

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

Question 29

Evolution by genetic drift is most obvious in

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

Question 30

Genetic drift results in a change in allele frequencies because

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

Question 31

Mutations

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

Question 32

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

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

Question 33

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

Question 34

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) genetic drift.
D) sexual selection.
E) natural selection.

Question 35

Which of the following mutations would increase evolutionary fitness?

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

Question 36

Which of the following can be measured to estimate an organism's evolutionary fitness?

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

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

Question 38

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

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

Question 39

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

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

Question 40

Mutations are important because they

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

Question 41

Natural selection selects for or against certain

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

Question 42

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

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

Question 43

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

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

Question 44

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 45

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

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

Question 46

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 47

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

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

Question 48

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

Question 49

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 50

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

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

Question 51

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

Question 52

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

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

Question 53

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) fitness.
C) random mutation.
D) sexual selection.
E) random evolution.

Question 54

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

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

Question 55

Evolution by natural selection is

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

Question 56

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

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

Question 57

The elaborate courtship displays common among animals are the result of

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

Question 58

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

Question 59

The male peacock's beautiful tail is really a trade- off between

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

Question 60

Which trait is the best example of an adaptation?

A) A mutation resulting in weak branches in a species of tree that lives in windy regions
B) A mutation resulting in a heat- resistant enzyme in a bacterium living in a hot spring
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 shorter neck in a giraffe that lives in an area with many rival males and tall trees

Question 61

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

Question 62

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

Question 63

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 64

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

Question 65

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 66

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

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

Question 67

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 68

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

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

Question 69

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

Question 70

Multidrug- resistant bacteria

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

Question 71

Natural selection causes genetic changes in populations.

Question 72

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

Question 73

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 74

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

Question 75

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

Question 76

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 77

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

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

Question 78

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 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 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