Introduction to Evolution and Population Genetics-Week 14

Question 1

In order for natural selection to occur within a population, certain conditions must be met. One condition is

heterozygosity must be very low.
phenotypic variations that are genetic.
frequent mutations that are inherited.
low rates of immigration.

Answer 1

phenotypic variations that are genetic.

Question 2

In the phalarope, or wade pipes bird, the male is unusual in playing the larger parenting role – he performs all the egg incubation and chick care. What unusual behavior might you predict for the female of the species?

The female is part of a large harem of females, under the domain of a single male.
The females compete to mate with the males, who choose among them.
The female provides sperm to fertilize the male’s eggs.
The females have dull, brown coloring that keeps them well-camouflaged.

Answer 2

The females compete to mate with the males, who choose among them.

Question 3

Darwin proposed that natural selection occurs in an environment by

favoring heritable features that make the organism better suited to survive and reproduce.
producing a constant number of offspring while in that environment.
surviving for a fixed amount of time.
favoring those individuals with the most favorable acquired characteristics.

Answer 3

favoring heritable features that make the organism better suited to survive and reproduce.

Question 4

When the function of an allele is influenced by the alleles of other genes elsewhere in the genome, the interaction is called _________and can affect selection for the allele.

incomplete dominance
epistasis
frequency-dependent selection
pleiotropy

Answer 4

epistasis

Question 5

Some flowering plants cannot self-pollinate which increases their tendency to mate with phenotypically different mates, a process called disassortative mating. What effect would this have on a population, compared to expectations based on the Hardy-Weinberg principle?

A decrease in heterozygotes would be observed.
An increase in heterozygotes would be observed.
No change homozygotes or heterozygotes would be observed.
The population would remain in Hardy-Weinberg equilibrium.

Answer 5

An increase in heterozygotes would be observed.

Question 6

In some instances environmental change causes a situation where one phenotype is favored for a period of time, and then a different phenotype is favored. This oscillating selection causes

extinction of the population.
the maintenance of genetic variation in the population.
high population increase to maintain phenotypic variation.
elimination of rarer genotypes because of uneven selection.

Answer 6

the maintenance of genetic variation in the population.

Question 7

Genotypes are said to be in _________ equilibrium if there is random mating and no other forces tend to alter the proportions of alleles from one generation to the next.

Hardy-Weinberg
Mendelian
frequency-dependent
homeostatic

Answer 7

Hardy-Weinberg

Question 8

Being born with extra fingers on a hand is called polydactyly. This is more common in some populations in North America than others due to _________.

an increase in mutation rate in these populations
random mating with other populations in North America
migration of people with multiple fingers out of the population
a founder effect because their ancestors from Europe carried the alleles

Answer 8

a founder effect because their ancestors from Europe carried the alleles

Question 9

People homozygous for the sickle-cell anemia allele develop a life-threatening disease, while those homozygous for the normal allele are at the highest risk of dying from malaria. Carriers have some resistance to malaria but do not develop sickle cell anemia. This is an example of _________

genetic bottleneck.
heterozygote advantage.
point mutation.
founder effect.

Answer 9

heterozygote advantage.

Question 10

Since females take on the larger parenting role in most species, what tendency do they have?

They fight for territory.
They produce large numbers of gametes.
They are the choosy sex.
They acquire polyandrous groups of male mates.

Answer 10

They are the choosy sex.

Question 11

About 80% of the alleles present in thoroughbred horses can be dated back to 31 known ancestors from the late eighteenth century. As a result, one would expect _________

Hardy-Weinberg equilibrium.
low rates of mutation.
little variation to select upon.
random mating.

Answer 11

little variation to select upon

Question 12

_________ would keep a population in Hardy-Weinberg equilibrium.

Random mating
Genetic drift
Selection
Gene flow

Answer 12

random mating

Question 13

There are more than 30 blood group genes in humans, in addition to the ABO locus, each with multiple alleles. This increases ____ in human populations.

gene flow
homozygosity
founder effects
genetic variability

Answer 13

genetic variability

Question 14

A population of flowers is in Hardy-Weinberg equilibrium with an allele frequency for white flowers (w) of 40%. What percentage of the flowers will have the colored or dominant phenotype?

16%
88%
60%
84%

Answer 14

84%

Question 15

Many male songbirds are brightly colored. However, the color of the birds is determined by a balance of

mutations that reduce bright colors and gene flow in favor of bright colors.
natural selection against bright colors by predation and sexual selection in favor of bright colors.
natural selection against bright colors by predation and mutations that introduce bright colors.
mutations that reduce bright colors and sexual selection in favor of bright colors.

Answer 15

natural selection against bright colors by predation and sexual selection in favor of bright colors.

Question 16

Platys and swordtails are related tropical freshwater fish. In studies, researchers have shown that female platys prefer males with swordtails, even though males of their own species do not have them. This was discovered by attaching artificial swordtails to platy males. What does this suggest about the origin of the swordtail feature?

Female preference for swords may have predated the origin of the feature itself.
Evolution of swords later led to evolution of female preference for swords.
The same gene that causes sword development also causes development of neural circuits for female preference.
Adjacent genes on the same chromosome cause sword development and development of neural circuits for female preference.

Answer 16

Female preference for swords may have predated the origin of the feature itself.

Question 17

The observation that many Native Americans have type O blood is best explained by _________

assortative mating.
gene flow.
founder effect.
frequent mutations.

Answer 17

founder effect

Question 18

In some instances environmental change causes a situation where one phenotype is favored for a period of time, and then a different phenotype is favored. This oscillating selection causes

elimination of rarer genotypes because of uneven selection.
the maintenance of genetic variation in the population.
extinction of the population.
high population increase to maintain phenotypic variation.

Answer 18

the maintenance of genetic variation in the population.

Question 19

Different species of picture-winged fruit flies in the Hawaiian Islands are genetically similar to each other, yet genetically different from their ancestral population in Asia. This is probably an example of _________

founder effect.
directional selection.
disruptive selection.
gene flow.

Answer 19

founder effect

Question 20

An insect population that becomes resistant to a plant’s toxin is an example of _________.

disruptive selection
genetic drift
gene flow
natural selection

Answer 20

natural selection

Question 21

When fisheries managers move fish from one lake to another, this causes gene _________.

blending
mutation
dominance
flow

Answer 21

flow

Question 22

In a forest, trees that grow taller get more sunlight and gain more energy than other nearby trees. This results in _________

artificial selection.
stabilizing selection.
disruptive selection.
directional selection.

Answer 22

directional selection

Question 23

Cheetahs have been through a genetic bottleneck; evidence for this is that

there is very little genetic variability.
they originally came from small areas of Africa.
these cats are members of an endangered species.
little natural selection occurs in this species.

Answer 23

there is little genetic variability

Question 24

A human autosomal recessive trait appears in 1 in 100 births. What percent of people are homozygous dominant for this gene?

18%
90%
1%
81%

Answer 24

81%

Question 25

Female cardinals select male mates in part based on their bright red color. What effect would this have on a cardinal population?

The frequency of red alleles would be greater than those predicted by Hardy-Weinberg equilibrium.
The red allele frequencies would remain unchanged because of equilibrium.
The frequency of red alleles would be less than those predicted by Hardy-Weinberg equilibrium.
The frequency of red alleles would be equal to those predicted by Hardy-Weinberg equilibrium.

Answer 25

The frequency of red alleles would be greater than those predicted by Hardy-Weinberg equilibrium.

Question 26

A population of lizards lives in a rocky area next to a desert. Some lizards are light-colored and blend into the sand. Others are dark and blend into the rocks. What may happen to this population of lizards over time?

They may remain one species as a result of directional selection.
They may remain one species as a result of disruptive selection.
They may remain one species as a result of stabilizing selection.
They may evolve into two separate species as a result of disruptive selection.

Answer 26

They may evolve into two separate species as a result of disruptive selection.

Question 27

Hardy-Weinberg pointed out that the original proportions of the genotypes in a population would remain constant from generation to generation if certain assumptions are met. Which one of the following is NOT a Hardy-Weinberg condition?

No polymorphic loci exist in the population.
No gene flow occurs.
Random mating occurs.
No selection occurs.

Answer 27

No polymorphic loci exist in the population.

Question 28

The organism with the highest fitness is:

An animal that lives 10 years and produces 2 offspring per year.
An animal that lives 100 years and produces 10 offspring total.
An animal that lives 10 years and produces 10 offspring per year.
An animal that lives one year and produces 10 offspring total.

Answer 28

An animal that lives 10 years and produces 10 offspring per year.

Question 29

The preservation of genes that increase the likelihood of survival and reproduction of some individuals within a population is called the process of

increasing evolutionary resistance.
genetic drift.
creation of new species.
natural selection.

Answer 29

natural selection

Question 30

Antigens on red blood cells are hereditary traits that allow blood to be typed in different ways. One system is based on a gene with two alleles, M and N. If the frequency of the M allele in a population is 0.4, then according to the Hardy-Weinberg rule, the expected frequency of the heterozygous MN genotype is _________.

0.16
0.6
0.48
0.24

Answer 30

0.48