Deck 10: Natural Selection: Empirical Studies in the Wild

Question 1

Analysis of allelic diversity in maize demonstrated that by 4400 years ago, maize had lost much of its genetic diversity. This loss of diversity can be explained by

A) a genetic bottleneck.
B) strong artificial selection.
C) genetic drift.
D) a and b
E) a, b, and c

Answer 1

D

Question 2

The Eda gene, which regulates growth of lateral armor plates in stickleback fishes,

A) codes for more armored plates in the recessive allele than the wild type.
B) is hard to study because the recessive condition affects surrounding tissue.
C) has variants responsible for much of the variation in the number of lateral plates each stickleback grows.
D) is easy to study because the recessive condition affects surrounding tissue.

Answer 2

C

Question 3

The difference in beak size between offspring of finches that survived the drought on Daphne Major and the population average before the drought is

A) the response to selection (R).
B) the selection differential (S).
C) heritability (H²).
D) the mutation rate (μ).

Answer 3

A

Question 4

If a population of gallflies occurred in an area where birds were present but parasitoid wasps were absent, which type of selection is most likely to affect gall size?

A) stabilizing
B) negative frequency-dependent
C) directional
D) disruptive

Question 5

After studying medium ground finch families from year to year, the Grants determined that beak size (length and depth) was highly heritable. This is primarily due to

A) the environment.
B) additive alleles.
C) epistatic alleles.
D) dominant alleles.

Question 6

Which of the following is not a gene identified in the evolution of maize morphology from a teosinte ancestor?

A) teosinte branched 1-represses growth of lateral meristems
B) prolamin box binding factor-produces seed storage proteins in kernels
C) IFG1-contributes to small body size
D) sugary 1-alters properties of starch in kernels

Question 7

Goldenrod gall size varies because of

A) fluids secreted by gallfly larvae that change gene expression of cells in the goldenrod plant.
B) inherited differences among gallflies.
C) inherited differences among goldenrod plants.
D) a and b
E) all of the above

Question 8

The example of the Agouti gene in snowshoe hares shows that

A) natural selection can rapidly spread an allele introduced into a species by hybridization.
B) the effect of natural selection can change in response to the changing climate.
C) a and b
D) none of the above

Question 9

Natural selection will act on goldenrod gall size when

A) all goldenrod gallflies are clones.
B) the size of galls produced by gallflies is heritable.
C) gall size does not affect the viability of the gallfly.
D) gall size does not affect the ability of the gallfly to produce offspring.

Question 10

Which of the following would not have been an advantage for the Grants when studying natural selection in the wild on Daphne Major?

A) The environment is pristine.
B) Some seed plant species went extinct after the humans arrived at the island.
C) There is little plant diversity, allowing easy identification and measurement of every type of seed.
D) Finch populations are small and rarely experience migration.

Question 11

Which of the following is true of F^ST, a measure of genetic distance between populations?

A) F^ST increases faster when subpopulations are small.
B) F^ST is useful to quantify how dramatically populations have diverged in their respective allele frequencies.
C) When F^ST = 0, allele frequencies are approximately the same from place to place.
D) all of the above

Question 12

Which of the following statements is/are true regarding oldfield mice on Florida's Atlantic Coast and Gulf Coast?
i. Light-colored mice on the Atlantic Coast lack the Gulf Coast alleles of Mc1r.
Ii. Light-colored mice on the Atlantic Coast share a common ancestor with Gulf Coast mice.
Iii. Light-colored mice evolved independently in the two locations.

A) i only
B) i and ii only
C) i and iii only
D) i, ii, and iii

Question 13

In a comparison of winter-white and winter-brown snowshoes,

A) F^ST in the polymorphic zone is generally very high.
B) F^ST for the region containing the Agouti gene is very high.
C) In winter-brown hares, expression of Agouti increased in the fall.
D) F^ST did not identify any genes responsible for coat color.

Question 14

Which of the following does not support Hoekstra's hypothesis for the evolution of coat color in oldfield mice?

A) Blending into the background reduced predation rate in both beach and mainland habitats.
B) Predation rates of dark clay models in beach habitats were higher relative to white models.
C) Predation rates of light models in mainland habitats were higher relative to dark models.
D) Camouflage increased predation rate in both beach and mainland habitats.

Question 15

There are as many as 18 species of Darwin's finches that have adapted to different feeding opportunities on the Galápagos islands. The Grants studied the medium ground finch (Geospiza fortis), which feeds primarily on

A) cactus flowers.
B) the blood of vertebrates.
C) seeds.
D) insects.

Question 16

In 1977, before the drought on Daphne Major, the average beak depth in the finch population was 9.2 mm. Finches that bred successfully during the drought had an average beak depth of 9.7 mm. The difference between these values represents

A) the response to selection (R).
B) the selection differential (S).
C) heritability (H²).
D) the mutation rate (μ).

Question 17

The "refuge" strategy proposed by Tabashnik to slow the evolution of Bt resistance relies on

A) the fact that Bt resistance is involved in a trade-off.
B) gene flow between refuge and susceptible populations.
C) a and b
D) none of the above

Question 18

Several studies have revealed that the Eda gene fulfills the three necessary conditions for evolution by selection. Which is not one of these conditions?

A) functional importance of armor for survival
B) extensive among-individual difference in phenotype
C) inherited genetic variation underlying phenotype differences
D) genetic fixation at the Eda gene

Question 19

What condition would increase the chances of a particular trait evolving by natural selection in response to a change in the environment?

A) a low mutation rate for the trait
B) high heritability of the trait
C) a small population size
D) less variation in fitness

Question 20

An extended phenotype

A) is a structure constructed by an organism.
B) has no noticeable effect on the organism.
C) is not a part of the organism.
D) a and b
E) a and c

Question 21

Which of the following does not support the hypothesis that evolution likely occurs over very long timescales?

A) The strength of natural selection from generation to generation is very weak.
B) The average beak size of the medium ground finch increased after one generation.
C) There are gradual changes in the fossil record.
D) all of the above

Question 22

Describe how natural selection could have led to a decrease in gape width of native Australian snakes since the introduction of toxic cane toads.

Question 23

In order to study the effect of natural selection, ideally which of the following would not be acting on the allele frequencies of populations in the wild?

A) gene flow from other populations
B) random fluctuations due to genetic drift
C) genetic mutations
D) all of the above

Question 24

Which of the following incorrectly matches the vegetable with the plant organ artificially selected for in wild cabbage (Brassica oleracea)?

A) kale-leaves
B) kohlrabi-stems
C) cabbage-flower shoots
D) brussels sprouts-buds

Question 25

Abrahamson and Weis did an experiment in which they compared the gall sizes produced on goldenrod clones by different families of gallflies. Why did the researchers use plant clones and compare gall sizes between gallfly families?

Question 26

Describe how Peter and Rosemary Grant demonstrated the following components, each of which is necessary to demonstrate evolution by natural selection: variation in the population, heritability, and differential reproductive success linked to variation.

Question 27

Compare the types of selection seen in medium ground finch beak size in the Galápagos Islands after the drought of 1977, in Australian snake gape width after the introduction of the cane toad, and in gall size produced by gallflies after selection by predatory birds and parasitoid wasps. For each scenario, draw a figure illustrating the type of selection acting on the population (draw the distribution of phenotypes in the population before and after selection). Indicate whether the selection is directional, stabilizing, or disruptive.

Question 28

A quantitative trait locus (QTL)

A) is a stretch of DNA correlated with variation in a phenotypic trait.
B) is a gene locus that is solely responsible for a single phenotype.
C) is a stretch of DNA that contains genes or is linked to genes that contribute to population differences in a phenotype.
D) a and c
E) b and c

Question 29

Evidence of glyphosate as a potent agent of selection on weed populations includes

A) independent mutations of a single amino acid in the EPSPS gene in ryegrass and goosegrass species, enabling plants to survive.
B) gene duplication in Palmer amaranth resulting in extra copies of the EPSPS gene so that enough enzyme is produced, enabling plants to survive.
C) a and b
D) none of the above

Question 30

Natural selection favors gallflies that produce intermediate gall sizes. This is an example of

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

Question 31

You learned how freshwater stickleback populations have lost their body armor through positive selection of a low-armor Eda allele, which is found at low frequency in marine populations. How could you determine whether the low-armor phenotype arose once and spread throughout freshwater populations, or whether the allele was selected for independently multiple times?

Question 32

The graph below shows the effect of hunting imposed on horn length in bighorn sheep populations. What type of selection does it show?

A) stabilizing
B) negative frequency-dependent
C) directional
D) disruptive

Question 33

Each year, the indigenous Zoque people of Mexico introduce barbasco, a compound that is toxic to fish, into the Cueva del Azufre (a cave) to kill and harvest fish during a religious ceremony. These fish also live in caves in which the ceremony is not performed. Design a study to examine whether fish in the Cueva del Azufre have evolved increased resistance to barbasco.

Question 34

Why did Melander suggest that farmers apply pesticides "poorly" to deal with the San Jose scale insect?

A) because some susceptible scales would survive, keeping susceptible genes in the scale population
B) because most scale insects do not respond to pesticides
C) because this would kill a smaller population of resistant scales
D) because few resistant scales would survive, keeping resistant genes out of the scale population
E) He did not suggest this. In order for pesticides to work, they must be applied heavily and properly.

Question 35

You learned how freshwater stickleback populations have lost their body armor through positive selection of a low-armor Eda allele, which is found at low frequency in marine populations. Draw (a) a phylogenetic tree that would support the hypothesis that the low-armor phenotype arose once and then spread throughout freshwater populations and (b) a phylogenetic tree that would support the hypothesis that the phenotype arose independently multiple times in freshwater populations.

Question 36

The intermediate gall sizes produced by gallflies are a result of
i. predatory birds selecting against large galls.
Ii) parasitoid wasps selecting against large galls.
Iii) parasitoid wasps selecting against small galls.
Iv) predatory birds selecting against small galls.

A) i and ii
B) i and iii
C) ii and iv
D) iii and iv

Question 37

Hopi Hoekstra and colleagues were interested in whether lighter coat coloration arose in Gulf and Atlantic Coast populations through convergent evolution. How did they test this, and what did they find?

Question 38

What did the Grants conclude about how selection acts on the medium ground finches from their long-term study of the birds on Daphne Major?

A) The strength of selection varies over time.
B) The direction of selection varies over time.
C) Beak size should continue to get larger over time.
D) a and b
E) a and c

Question 39

Compare the selection of coat color in oldfield mice and in the snowshoe hare.

Question 40

Which of the following was necessary for the evolution of beak size on Daphne Major?

A) Beak size had to be at least partially determined by the additive effects of alleles.
B) Characteristics of the available seeds had to change from year to year.
C) Individuals with smaller beaks had to grow larger beaks during drought years.
D) a and b
E) a, b, and c