18.E: Evolution and the Origin of Species (Exercises)

18.1: Understanding Evolution

Review Questions

Which scientific concept did Charles Darwin and Alfred Wallace independently discover?

1. mutation
2. natural selection
3. overbreeding
4. sexual reproduction

Answer

B

Which of the following situations will lead to natural selection?

1. The seeds of two plants land near each other and one grows larger than the other.
2. Two types of fish eat the same kind of food, and one is better able to gather food than the other.
3. Male lions compete for the right to mate with females, with only one possible winner.
4. all of the above

Answer

D

Which description is an example of a phenotype?

1. A certain duck has a blue beak.
2. A mutation occurred to a flower.
3. Most cheetahs live solitary lives.
4. both a and c

Answer

D

Which situation is most likely an example of convergent evolution?

1. Squid and humans have eyes similar in structure.
2. Worms and snakes both move without legs.
3. Some bats and birds have wings that allow them to fly
4. all of the above

Answer

D

Free Response

If a person scatters a handful of garden pea plant seeds in one area, how would natural selection work in this situation?

Answer

The plants that can best use the resources of the area, including competing with other individuals for those resources will produce more seeds themselves and those traits that allowed them to better use the resources will increase in the population of the next generation.

Why do scientists consider vestigial structures evidence for evolution?

Answer

Vestigial structures are considered evidence for evolution because most structures do not exist in an organism without serving some function either presently or in the past. A vestigial structure indicates a past form or function that has since changed, but the structure remains present because it had a function in the ancestor.

How does the scientific meaning of “theory” differ from the common vernacular meaning?

Answer

In science, a theory is a thoroughly tested and verified set of explanations for a body of observations of nature. It is the strongest form of knowledge in science. In contrast, a theory in common vernacular can mean a guess or speculation about something, meaning that the knowledge implied by the theory is very weak.

Explain why the statement that a monkey is more evolved than a mouse is incorrect.

Answer

The statement implies that there is a goal to evolution and that the monkey represents greater progress to that goal than the mouse. Both species are likely to be well adapted to their particular environments, which is the outcome of natural selection.

18.2: Formation of New Species

Review Questions

Which situation would most likely lead to allopatric speciation?

1. flood causes the formation of a new lake.
2. A storm causes several large trees to fall down.
3. A mutation causes a new trait to develop.
4. An injury causes an organism to seek out a new food source.

Answer

A

What is the main difference between dispersal and vicariance?

1. One leads to allopatric speciation, whereas the other leads to sympatric speciation.
2. One involves the movement of the organism, and the other involves a change in the environment.
3. One depends on a genetic mutation occurring, and the other does not.
4. One involves closely related organisms, and the other involves only individuals of the same species.

Answer

B

Which variable increases the likelihood of allopatric speciation taking place more quickly?

1. lower rate of mutation
2. longer distance between divided groups
3. increased instances of hybrid formation
4. equivalent numbers of individuals in each population

Answer

B

What is the main difference between autopolyploid and allopolyploid?

1. the number of chromosomes
2. the functionality of the chromosomes
3. the source of the extra chromosomes
4. the number of mutations in the extra chromosomes

Answer

C

Which reproductive combination produces hybrids?

1. when individuals of the same species in different geographical areas reproduce
2. when any two individuals sharing the same habitat reproduce
3. when members of closely related species reproduce
4. when offspring of the same parents reproduce

Answer

C

Which condition is the basis for a species to be reproductively isolated from other members?

1. It does not share its habitat with related species.
2. It does not exist out of a single habitat.
3. It does not exchange genetic information with other species.
4. It does not undergo evolutionary changes for a significant period of time.

Answer

C

Which situation is not an example of a prezygotic barrier?

1. Two species of turtles breed at different times of the year.
2. Two species of flowers attract different pollinators.
3. Two species of birds display different mating dances.
4. Two species of insects produce infertile offspring.

Answer

D

Free Response

Why do island chains provide ideal conditions for adaptive radiation to occur?

Answer

Organisms of one species can arrive to an island together and then disperse throughout the chain, each settling into different niches and exploiting different food resources to reduce competition.

Two species of fish had recently undergone sympatric speciation. The males of each species had a different coloring through which the females could identify and choose a partner from her own species. After some time, pollution made the lake so cloudy that it was hard for females to distinguish colors. What might take place in this situation?

Answer

It is likely the two species would start to reproduce with each other. Depending on the viability of their offspring, they may fuse back into one species.

Why can polyploidy individuals lead to speciation fairly quickly?

Answer

The formation of gametes with new n numbers can occur in one generation. After a couple of generations, enough of these new hybrids can form to reproduce together as a new species.

18.3: Reconnection and Rates of Speciation

Review Questions

Which term is used to describe the continued divergence of species based on the low fitness of hybrid offspring?

1. reinforcement
2. fusion
3. stability
4. punctuated equilibrium

Answer

A

Which components of speciation would be least likely to be a part of punctuated equilibrium?

1. a division of populations
2. a change in environmental conditions
3. ongoing gene flow among all individuals
4. a large number of mutations taking place at once

Answer

C

Free Response

What do both rate of speciation models have in common?

Answer

Both models continue to conform to the rules of natural selection, and the influences of gene flow, genetic drift, and mutation.

Describe a situation where hybrid reproduction would cause two species to fuse into one.

Answer

If the hybrid offspring are as fit or more fit than the parents, reproduction would likely continue between both species and the hybrids, eventually bringing all organisms under the umbrella of one species.