Question 1

Which condition is least likely to lead to geographic isolation, hence inhibiting allopatric speciation?

Accepted Answer

A)  A lava flow in Iceland dividing a population of white Angora rabbits into two populations 
B)  A fire dividing a population of bats into two populations 
C)  A hurricane destroying a large portion of grassland, thereby creating two populations of snails 
D)  A deep gorge dividing a population of slow-moving snails 
E)  A land bridge dividing a population of tuna 
A)  A lava flow in Iceland dividing a population of white Angora rabbits into two populations 
B)  A fire dividing a population of bats into two populations 
C)  A hurricane destroying a large portion of grassland, thereby creating two populations of snails 
D)  A deep gorge dividing a population of slow-moving snails 
E)  A land bridge dividing a population of tuna

Question 2

Hybrid zones are likely to be narrow

Accepted Answer

A)  in species that shift locations considerably during their lifetimes. 
B)  when reinforcement is occurring. 
C)  when there is strong selection against the hybrids. 
D)  when the hybrids are as fit as the original species. 
E)  when hybrids are formed in marine species. 
A)  in species that shift locations considerably during their lifetimes. 
B)  when reinforcement is occurring. 
C)  when there is strong selection against the hybrids. 
D)  when the hybrids are as fit as the original species. 
E)  when hybrids are formed in marine species.

Question 3

Theoretical work that follows from the Dobzhansky-Muller model predicts that the number of incompatible sets of genes should increase roughly with the square of the divergence time between the two incipient species, a phenomenon known as "snowballing." Empirical studies provide some support for this snowballing.Based on the Dobzhansky-Muller model, why would you expect snowballing?

Accepted Answer

The Dobzhansky-Muller model assumes that

Question 4

Which is a postzygotic mechanism of isolation?

Accepted Answer

A)  Behavioral isolation 
B)  Temporal isolation 
C)  Mechanical isolation 
D)  Hybrid infertility 
E)  Gametic isolation 
A)  Behavioral isolation 
B)  Temporal isolation 
C)  Mechanical isolation 
D)  Hybrid infertility 
E)  Gametic isolation

Question 5

Refer to the figure.   The figure shows the Dobzhansky-Muller model of the evolution of reproductive isolation.The F1 hybrids between the species at the end of this process have reduced fitness.Which genotype has reduced fitness?

Accepted Answer

A)  aabb 
B)  AAbb 
C)  AaBb 
D)  aaBB 
E)  aaBb 
A)  aabb 
B)  AAbb 
C)  AaBb 
D)  aaBB 
E)  aaBb

Question 6

If the hybrids of two salamander species exhibit reduced adult viability, these species have a(n) _______ reproductive isolating barrier.

Accepted Answer

The answer of If the hybrids of two salamander species...

Question 7

According to the Dobzhansky-Muller model, the evolution of reproductive isolation requires changes in (at least) _______ genetic loci.

Accepted Answer

The answer of According to the Dobzhansky-Muller model, the evolution...

Question 8

The genes F and G act in accordance with the Dobzhansky-Muller model, leading to sterility in hybrids between two species of monkeyflowers.Any combination of the F1 and the G2 alleles causes hybrids to be sterile.Based on the Dobzhansky-Muller model, which genotype should have low fitness?

Accepted Answer

A)  F1F1; G1G1 
B)  F1F1; G2G2 
C)  F0F0; G2G2 
D)  F2F2; G0G0 
E)  F2F2; G2G2 
A)  F1F1; G1G1 
B)  F1F1; G2G2 
C)  F0F0; G2G2 
D)  F2F2; G0G0 
E)  F2F2; G2G2

Question 9

Geographic isolation

Accepted Answer

A)  always results in reproductive isolation. 
B)  always results in the formation of new species. 
C)  is required for speciation. 
D)  can affect mating probabilities between two separated populations. 
E)  has the same effects on all organisms. 
A)  always results in reproductive isolation. 
B)  always results in the formation of new species. 
C)  is required for speciation. 
D)  can affect mating probabilities between two separated populations. 
E)  has the same effects on all organisms.

Question 10

The genes H and K act in accordance with the Dobzhansky-Muller model, leading to sterility in hybrids between two species of monkeyflowers.Any combination of the H2 and the K1 alleles causes hybrids to be sterile.Based on the Dobzhansky-Muller model, which genotype should have high fitness?

Accepted Answer

A)  H1H1; K1K1 
B)  H1H2; K2K2 
C)  H2H0; K1K2 
D)  H1H2; K0K1 
E)  H1H2; K1K1 
A)  H1H1; K1K1 
B)  H1H2; K2K2 
C)  H2H0; K1K2 
D)  H1H2; K0K1 
E)  H1H2; K1K1

Question 11

The proliferation of a large number of descendant species from a single ancestor is known as

Accepted Answer

A)  cryptic speciation. 
B)  the speciation rate. 
C)  an evolutionary radiation. 
D)  a lek. 
E)  sexual selection. 
A)  cryptic speciation. 
B)  the speciation rate. 
C)  an evolutionary radiation. 
D)  a lek. 
E)  sexual selection.

Question 12

The genes F and G act in accordance with the Dobzhansky-Muller model leading to sterility in hybrids between two species of monkeyflowers.Any combination of the F2 and the G1 alleles causes hybrids to be sterile.Hybrids between populations that are F1F1G1G1 and F2F2G0G0 should have the genotype _______ and thus have low fitness.

Accepted Answer

Question 13

Crosses between lines of phlox that had been bred by breeders

Accepted Answer

A)  provide support for the Dobzhansky-Muller model of reproductive isolation. 
B)  challenge the Dobzhansky-Muller model of reproductive isolation 
C)  show that reproductive isolation can evolve in a couple of centuries. 
D)  show that the evolution of reproductive isolation requires many thousands of years. 
E)  show that polyploidy is an effective way for speciation to occur quickly. 
A)  provide support for the Dobzhansky-Muller model of reproductive isolation. 
B)  challenge the Dobzhansky-Muller model of reproductive isolation 
C)  show that reproductive isolation can evolve in a couple of centuries. 
D)  show that the evolution of reproductive isolation requires many thousands of years. 
E)  show that polyploidy is an effective way for speciation to occur quickly.

Question 14

Which factor did not contribute to the genetic diversification of the Galápagos Island finches studied by Darwin?

Accepted Answer

A)  Environmental conditions varying among the different islands 
B)  Most of the islands being sufficiently distant from one another such that movement among their populations was limited 
C)  The islands being only 100 km from Ecuador, so they received a continual input of new genes from the mainland 
D)  Occasional migrants to new islands rarely interbreeding with endemic species 
E)  Over time, the residents of each island developed their own genetic distinctiveness 
A)  Environmental conditions varying among the different islands 
B)  Most of the islands being sufficiently distant from one another such that movement among their populations was limited 
C)  The islands being only 100 km from Ecuador, so they received a continual input of new genes from the mainland 
D)  Occasional migrants to new islands rarely interbreeding with endemic species 
E)  Over time, the residents of each island developed their own genetic distinctiveness

Question 15

Refer to the figure.   Drosophila species that have been crossed with each other allow evolutionary biologists to make general inferences about their evolution.The figure shows the relationship between prezygotic reproductive isolation and genetic distance for both allopatric and sympatric pairs.What does the graph show regarding the difference between allopatric and sympatric pairs of species with respect to how reproductive isolation evolves with increasing genetic distance?

Accepted Answer

Pairs that are sympatric accum

Question 16

Allopatric speciation cannot result when a population

Accepted Answer

A)  becomes separated by a large lake. 
B)  becomes separated by a desert. 
C)  becomes geographically isolated by a range of mountains. 
D)  evolves into two sister species while sharing the same geographic range. 
E)  becomes isolated on several islands as sea level rises. 
A)  becomes separated by a large lake. 
B)  becomes separated by a desert. 
C)  becomes geographically isolated by a range of mountains. 
D)  evolves into two sister species while sharing the same geographic range. 
E)  becomes isolated on several islands as sea level rises.

Question 17

Natural selection would rarely favor the evolution of which type of reproductive isolating barriers?

Accepted Answer

A)  Mechanical isolation 
B)  Gametic isolation 
C)  Behavioral isolation 
D)  Temporal isolation 
E)  Hybrid infertility 
A)  Mechanical isolation 
B)  Gametic isolation 
C)  Behavioral isolation 
D)  Temporal isolation 
E)  Hybrid infertility

Question 18

Two populations of snails are allopatric, living in areas that have different compositions of soil types.The snails live in soil and are not very mobile.Researchers are interested in whether the populations have acquired different types of reproductive isolation.What would be the best way to test whether these populations exhibit habitat isolation?

Accepted Answer

A)  Examine the preference of soil types of each population. If they have similar preferences, then they likely exhibit habitat isolation. 
B)  Examine the preference of soil types of each population. If they have different preferences, then they likely exhibit habitat isolation. 
C)  Observe when each population is active. If they are active at very different times, then they likely exhibit habitat isolation. 
D)  Observe when each population is active. If they are active at the same time, then they likely exhibit habitat isolation. 
E)  Bring them into the lab. Have the females from one population mate with males from another. Count the number of offspring. If few offspring are produced, then they likely exhibit temporal isolation. 
A)  Examine the preference of soil types of each population. If they have similar preferences, then they likely exhibit habitat isolation. 
B)  Examine the preference of soil types of each population. If they have different preferences, then they likely exhibit habitat isolation. 
C)  Observe when each population is active. If they are active at very different times, then they likely exhibit habitat isolation. 
D)  Observe when each population is active. If they are active at the same time, then they likely exhibit habitat isolation. 
E)  Bring them into the lab. Have the females from one population mate with males from another. Count the number of offspring. If few offspring are produced, then they likely exhibit temporal isolation.

Question 19

Two populations of snails are allopatric, living in areas that have different compositions of soil types.The snails live in soil and are not very mobile.Researchers are interested in whether the populations have acquired different types of reproductive isolation.Which method would be best to determine whether two populations exhibited behavioral isolation?

Accepted Answer

A)  Move them into a common experimental setting to see if they will produce offspring. If they produce offspring, they exhibit behavioral isolation. 
B)  Move them into a common experimental setting to see if they will produce offspring. If they do not produce offspring, they exhibit behavioral isolation. 
C)  Bring them into the lab. Observe single pairs of a male from one population and a female from the other. If they mate, then they exhibit behavioral isolation. 
D)  Bring them into the lab. Observe single pairs of a male from one population and a female from the other. If they do not mate, then they exhibit behavioral isolation. 
E)  Observe when each population is active. If they are active at the same time, then they exhibit behavioral isolation. 
A)  Move them into a common experimental setting to see if they will produce offspring. If they produce offspring, they exhibit behavioral isolation. 
B)  Move them into a common experimental setting to see if they will produce offspring. If they do not produce offspring, they exhibit behavioral isolation. 
C)  Bring them into the lab. Observe single pairs of a male from one population and a female from the other. If they mate, then they exhibit behavioral isolation. 
D)  Bring them into the lab. Observe single pairs of a male from one population and a female from the other. If they do not mate, then they exhibit behavioral isolation. 
E)  Observe when each population is active. If they are active at the same time, then they exhibit behavioral isolation.

Question 20

Refer to the table.   Certain populations of a copepod (a planktonic crustacean) may be reproductively isolated, even though females will mate with any male.Here, three females from one of the populations are placed with three males from another population.The diagonals represent crosses made between males and females of the same population.The numbers of offspring produced are listed in the table.Population 1 shows reproductive isolation with population(s) _______.(Enter as many as there are.If the population does not show reproductive isolation with any of the other populations, write in zero).

Accepted Answer

The answer of Refer to the table.   Certain...

Exam 22: Speciation

Which condition is least likely to lead to geographic isolation, hence inhibiting allopatric speciation?

Hybrid zones are likely to be narrow

Which is a postzygotic mechanism of isolation?

Refer to the figure. The figure shows the Dobzhansky-Muller model of the evolution of reproductive isolation.The F1 hybrids between the species at the end of this process have reduced fitness.Which genotype has reduced fitness?

If the hybrids of two salamander species exhibit reduced adult viability, these species have a(n) _______ reproductive isolating barrier.

According to the Dobzhansky-Muller model, the evolution of reproductive isolation requires changes in (at least) _______ genetic loci.

The genes F and G act in accordance with the Dobzhansky-Muller model, leading to sterility in hybrids between two species of monkeyflowers.Any combination of the F1 and the G2 alleles causes hybrids to be sterile.Based on the Dobzhansky-Muller model, which genotype should have low fitness?

Geographic isolation

The genes H and K act in accordance with the Dobzhansky-Muller model, leading to sterility in hybrids between two species of monkeyflowers.Any combination of the H2 and the K1 alleles causes hybrids to be sterile.Based on the Dobzhansky-Muller model, which genotype should have high fitness?

The proliferation of a large number of descendant species from a single ancestor is known as

Crosses between lines of phlox that had been bred by breeders

Which factor did not contribute to the genetic diversification of the Galápagos Island finches studied by Darwin?

Allopatric speciation cannot result when a population

Natural selection would rarely favor the evolution of which type of reproductive isolating barriers?

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Refer to the figure. The figure shows the Dobzhansky-Muller model of the evolution of reproductive isolation.The F₁ hybrids between the species at the end of this process have reduced fitness.Which genotype has reduced fitness?