Question 1

The article mentions that Historically, there had been gene flow between Texas cougars and Florida panthers. This means that:

Accepted Answer

the Texas cougar and the Florida panther have interbred with each other in the past.

Question 2

Which statement about inbreeding is correct? See Section 23.2 and article on Florida panthers.

Accepted Answer

Inbreeding changes allele frequencies in a population.

Question 3

Which of the following was NOT a consequence of breeding Texas panthers with the Florida panthers?

Accepted Answer

hybrid panthers had kinked tails

Question 4

Which type of selection tends to increase genetic variation?

Accepted Answer

Disruptive selection eliminates phenotypes near the average and favors the extreme phenotypes, resulting in increased genetic variation in a population.

Question 5

In a bell-shaped curve, the x-axis (horizontal direction) of the graph represents which of the following?In a bell-shaped curve, the x-axis (horizontal direction) of the graph represents which of the following?

Accepted Answer

The value of a particular characteristic; characteristics of an organism can include such traits as size and color.

Question 6

True or false? Heterozygote advantage refers to the tendency for heterozygous individuals to have better fitness than homozygous individuals. This higher fitness results in less genetic variation in the population.

Accepted Answer

False. Heterozygote advantage results in more genetic variation in the population.

Question 7

Long necks make it easier for giraffes to reach leaves high on trees, while also making them better fighters in neck wrestling contests. In both cases, which kind of selection appears to have made giraffes the long-necked creatures they are today?

Accepted Answer

Directional selection

Question 8

Women often have complications during labor while giving birth to very large babies, whereas very small babies tend to be underdeveloped. Which kind of selection is most likely at work regarding the birth weight of babies?

Accepted Answer

Stabilizing selection

Question 9

Black-bellied seedcrackers have either small beaks (better for eating soft seeds) or large beaks (better for hard seeds). There are no seeds of intermediate hardness; therefore, which kind of selection acts on beak size in seedcrackers?

Accepted Answer

Disruptive selection

Question 10

Small Aristelliger lizards have difficulty defending territories, but large lizards are more likely to be preyed upon by owls. Which kind of selection acts on the adult body size of these lizards?

Accepted Answer

Stabilizing selection

Question 11

What term is defined as the change in allele frequencies that occurs when a new population is established? See Section 23.4

Accepted Answer

Founder effect is a change in allele frequencies because the founder group is a small subset of the population, and thus is not likely to be completely representative of the entire population.

Question 12

Which statement about genetic drift is correct? See Section 23.4

Accepted Answer

The direction of evolutionary change due to genetic drift is random. Genetic drift is not driven by a directional effect but occurs as a magnification of chance effects due to small population size.

Question 13

How might genetic drift be important in a small population. See Section 23.4

Accepted Answer

It decreases genetic diversity via the loss of alleles due to inbreeding depression. Genetic drift is of large concern with populations of a small size because you are more likely to have mating between close relatives.

Question 14

How might gene flow be important in managing an endangered population? See Section 23.

Accepted Answer

It increases genetic diversity by introducing alleles from one population into another.

Question 15

Which evolutionary mechanism increases genetic variation in a population? See Section 23.6

Accepted Answer

Mutation

Question 16

Natural Selection

Accepted Answer

- a result of differential success in reproduction-cannot cause a harmful allele to become more common-consistently causes a population to become better adapted to its environment

Question 17

Genetic Drift

Accepted Answer

-responsible for the bottleneck effect-responsible for the founder effect-causes allele frequencies to fluctuate

Question 18

Gene Flow

Accepted Answer

-a result of the movement of fertile individuals or their gametes-can introduce new alleles into a population's gene pool

Question 19

During an extreme heat wave, plants with white flowers survive better

Accepted Answer

Natural Selection, frequency of white allele increases

Question 20

A person uproots the five closest plants, which all happen to be white flowers.

Accepted Answer

Genetic Drift, frequency of purple allele increases

Question 21

A storm kills many plants at random

Accepted Answer

Genetic Drift, allele frequencies change but no predictably

Question 22

Plants with purple flowers attract more insects, which pollinate the plants

Accepted Answer

Natural Selection, frequency of purple allele increase

Question 23

Workers from a nearby greenhouse accidentally introduce white flower seeds into this population's habitat

Accepted Answer

Gene Flow, frequency of white allele increases

Question 24

The Hardy-Weinberg principle played an important role in the synthesis of _ genetics and _ evolution

Accepted Answer

Mendelian ; Darwinian

Question 25

The _ hypothesis can serve as a _ hypothesis in evolutionary studies because it predicts what genotype and allele frequencies are expected if mating is random with respect to the gene in question and if none of the four evolutionary processes is operating on that gene.

Accepted Answer

Hardy-Weinberg; null

Question 26

Nonrandom mating changes only _ frequencies not _ frequencies, so is not an evolutionary process itself

Accepted Answer

genotype; allele

Question 27

Inbreeding- mating among relatives (or in some species, self-fertilization), is a form of _ mating. It leads to an increase in _ and a decrease in _ .

Accepted Answer

nonrandom; homozygosity; heterozygosity

Question 28

Inbreeding can accelerate _ and can cause inbreeding _.

Accepted Answer

Natural Selection; depression

Question 29

_ is the only evolutionary process that produces an adaption.

Accepted Answer

Natural Selection

Question 30

_ favors phenotypes at one end of a distribution, causing the average phenotype to change. It tends to decrease the diversity of alleles in populations.

Accepted Answer

Directional

Question 31

_ eliminates phenotypes with extreme characteristics. It decreases the diversity of alleles in populations.

Accepted Answer

Stabilizing selection

Question 32

_ favors extreme phenotypes and thus maintains genetic variation in populations. Disruptive selection sometimes leads to the _ of new species.

Accepted Answer

Disruptive selection; formation

Question 33

_ occurs when no single phenotype is favored; there is a balance among alleles in terms of fitness and frequency. [It] preserves _.

Accepted Answer

Balancing selection; genetic variation

Question 34

_ is a type of natural selection that leads to the evolution of trait that enable individuals to attract mates. Its usually has a stronger effect on _ than on _.

Accepted Answer

Sexual Selection; males; females

Question 35

The most common form of _ occurs when females choose to mate with males who exhibit good alleles or ability to provide resources to females.

Accepted Answer

Intersexual selection

Question 36

The most common form of _ occurs when males compete with each other to gain access to female mates.

Accepted Answer

Intrasexual selection

Question 37

Genetic Drift causes random changes in _ frequencies.

Accepted Answer

allele

Question 38

Genetic drift is particularly important in small populations, and it tends to _ overall genetic diversity.

Accepted Answer

reduce

Question 39

_ can result from random fusion of gametes at fertilization, founder events, and population bottlenecks.

Accepted Answer

Genetic Drift

Question 40

Gene Flow tends to _ allele frequencies among populations.

Accepted Answer

equalize

Question 41

Gene flow can introduce alleles from one population to _ when individuals move among populations.

Accepted Answer

another

Question 42

Mutation is the only evolutionary process that creates _ alleles. They may be beneficial, neutral, or deleterious.

Accepted Answer

new

Question 43

Sometimes a loss-of-function allele can be _.

Accepted Answer

adaptive

Question 44

Mutation occurs by _, not because an organism wants or needs a new allele.

Accepted Answer

chance

Question 45

Mutation occurs too infrequently to be a major cause of change in allele frequency _ , but it is important when _ with natural selection, genetic drift, and gene flow.

Accepted Answer

alone;combined

Question 46

Increases the frequency of certain alleles-the ones that contribute to reproductive success in a particular enviornment

Accepted Answer

Natural Selection

Question 47

Whoever founds a new generation determines the new allele frequencies

Accepted Answer

Founder effect

Question 48

A lot of the population dies randomly and the survivor's allele frequencies determine the proceeding generation's

Accepted Answer

Genetic Bottleneck

Question 49

Alleles (NOT ORGANISMS) moving between populations

Accepted Answer

Gene Flow

Question 50

A random fluctuation in Gene Frequency

Accepted Answer

Genetic Drift

Question 51

Often favors certain alleles and leads to a decrease in overall genetic variation in a population

Accepted Answer

Natural Selection

Question 52

Tends to decrease genetic Diversity over time, as alleles are randomly lost or fixed in a population

Accepted Answer

Genetic Drift

Question 53

Increases genetic diversity in a recipient population if new alleles arrive with immigrating individuals. May decrease if alleles leave with emigrating individuals.

Accepted Answer

Gene Flow

Question 54

Change in single base-pair in DNA

Accepted Answer

point mutation

Question 55

Change in number or composition of chromosomes

Accepted Answer

chromosomal mutation

Question 56

Transfer of genes from one species to another, instead of parent to offspring.

Accepted Answer

Lateral Gene Transfer

Question 57

Neutral Alleles

Accepted Answer

have no affect on fitness (silent mutation)

Question 58

Slowest evolutionary process (in non-bacteria and non-archaea) but strong when combined with others

Accepted Answer

Mutation

Question 59

Why don't deleterious mutations drop fitness?

Accepted Answer

Beneficial mutations cause upward leaps in fitness because natural selection favors individuals with the mutation, rapidly increasing the frequency of the mutation in the population. Deleterious mutations do not cause steep downward drops in average fitness in a population, because few individuals ever pass on the deleterious mutation due to their lower reproductive success (purifying selection tends to eliminate these alleles).

Question 60

Sometimes a loss-of-function mutation can be adaptive

Accepted Answer

Green aphids had deletion of their carotenoid synthesis-genes

Question 61

The ultimate source of genetic variation

Accepted Answer

Mutation

Question 62

If this did not occur, evolution would stop

Accepted Answer

Mutation

Question 63

Certain alleles favored and increase in frequency, while others are disfavored and decrease

Accepted Answer

Natural Selection

Question 64

Random changes in allele frequencies: most important in small populations

Accepted Answer

Genetic drift

BIOL 2130 Chapter 23 Evolutionary Processes

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