Biological Science

Scott Freeman, Lizabeth Allison, Michael Black

Chapter 27

Speciation - all with Video Answers

Educators

Chapter Questions

Problem 1

What distinguishes a morphospecies?
a. It has distinctive characteristics, such as size, shape, or coloration.
b. It represents a distinct twig in a phylogeny of populations.
c. It is reproductively isolated from other species.
d. It is a fossil from a distinct time in Earth history.

Courtney Burson

Courtney Burson

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Problem 2

Which of the following describes vicariance?
a. Small populations coalesce into one large population.
b. A population is fragmented into isolated subpopulations.
c. Individuals colonize a novel habitat.
d. Individuals disperse and found a new population.

Courtney Burson

Courtney Burson

Numerade Educator

Problem 3

Why are genetic isolation and genetic divergence occurring in apple maggot flies, even though populations occupy the same geographic area?
a. Different populations feed and mate on different types of fruit.
b. One population is tetraploid; others are diploid.
c. The introduction of a nonnative host plant caused vicariance.
d. Responses to scents have changed due to disruptive selection.

Courtney Burson

Courtney Burson

Numerade Educator

Problem 4

The biological species concept can be applied only to which of the following groups?
a. bird species living today
b. dinosaurs and bird species living today
c. dinosaurs
d. bacteria

Courtney Burson

Courtney Burson

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Problem 5

Why is "reinforcement" an appropriate name for the concept that natural selection should favor divergence and genetic isolation if populations experience postzygotic isolation?
a. Selection should reinforce high fitness for hybrid offspring.
b. Selection should reinforce the fact that the diverging populations are "good species" under the morphological species concept.
c. Hybrid offspring do not develop at all or are sterile when mature because selection reinforces only the success of purebred species.
d. The selected traits reinforce differences that evolved while the populations were isolated from one another.

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Courtney Burson

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Problem 6

True or False? Gene flow increases the divergence of populations.

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Courtney Burson

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Problem 7

Which studies in this chapter represent direct observation of speciation? Which are indirect studies of historical speciation events?

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Courtney Burson

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Problem 8

When the ranges of two different species meet, a stable "hybrid zone" occupied by hybrid individuals may form. How is this possible?
a. Hybrid individuals may have intermediate characteristics that are advantageous in a given region.
b. Hybrid individuals are always allopolyploid and are thus unable to mate with either of the original species.
c. Hybrid individuals may have reduced fitness and thus be strongly selected against.
d. One species has a selective advantage, so as hybridization continues, the other species will go extinct.

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Courtney Burson

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Problem 9

In the case of the seaside sparrow, how did the species identified by the biological species concept, the morphospecies concept, and the phylogenetic species concept conflict?

Courtney Burson

Courtney Burson

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Problem 10

Explain how isolation and divergence are occurring in apple maggot flies. Of the four evolutionary processes (mutation, gene flow, genetic drift, and selection), which two are most important in causing this event?

Courtney Burson

Courtney Burson

Numerade Educator

Problem 11

A large amount of gene flow is now occurring among human populations due to intermarriage among people from different ethnic groups and regions of the world. Is this phenomenon increasing or decreasing racial differences in our species? Explain.

Courtney Burson

Courtney Burson

Numerade Educator

Problem 12

If one species $(2 n=10)$ crosses with another species $(2 n=18),$ producing an allopolyploid offspring, what is the ploidy of the offspring?
a. $2 n=10$
b. $2 n=18$
c. $2 n=18+10=28$
d. $4 n=36+20=56$

Courtney Burson

Courtney Burson

Numerade Educator

Problem 13

Unlike animal gametes, plant reproductive cells do not differentiate until late in life. Why are plants much more likely than animals to produce diploid gametes and polyploid offspring?
a. Cells that do not divide for long periods accumulate mutations.
b. Cells that differentiate later in life undergo many rounds of mitosis, so are more likely to accumulate mutations.
c. Cells that differentiate later in life undergo many rounds of meiosis, so are more likely to accumulate mutations.
d. Undifferentiated cells are more prone to mutations than differentiated cells.

Courtney Burson

Courtney Burson

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Problem 14

Sexual selection is a type of natural selection that favors individuals with traits that increase their ability to obtain mates, such as female choice for bright orange beaks in zebra finches. Propose a scenario where sexual selection could contribute to divergence in sympatric speciation.

Courtney Burson

Courtney Burson

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Problem 15

A friend says that apple maggot flies prefer apple fruit scents because they need to, in order to survive. Another agrees and adds that the flies acquire the ability to distinguish the apple scents by spending time on the fruit, and that's why their offspring prefer apples. What's wrong with these statements?

Courtney Burson

Courtney Burson

Numerade Educator

Problem 16

All over the world, natural habitats are being fragmented into tiny islands as suburbs, ranches, and farms expand, and roads are built to connect them. Explain why this fragmentation process could lead to extinction. Then explain how it could lead to speciation.

Courtney Burson

Courtney Burson

Numerade Educator