Question 1

Reproductive isolation is ______ by natural selection to lead to speciation.

Accepted Answer

reinforced

Question 2

Scientists found that different beak shapes lead to different mating songs in Darwin's finches. This result best supports which hypothesis?

Accepted Answer

Adaptation to different food sources led to changes in beak shape, which in turn affected mating songs, contributing to behavioral isolation.

Question 3

Scientists studying a group of related bird species on an island archipelago discover that these species are always more closely related to each other within an island than they are between any two islands. The most likely explanation for this result is that

Accepted Answer

The pattern observed suggests that a single bird species colonized each island and then underwent speciation on that island, likely due to character displacement and adaptation to the specific environment of each island.

Question 4

Studies of snapping shrimp on either side of the Isthmus of Panama have shown that each Caribbean shrimp species is more closely related to a Pacific shrimp species than it is to any other Caribbean shrimp species. The most likely explanation for this result is

Accepted Answer

The formation of the Isthmus of Panama separated populations of snapping shrimp, leading to divergence and speciation on either side.

Question 5

Two hundred years ago, the fly species Rhagoletis pomonella only laid its eggs on fruit of the hawthorn tree. Today, different "host races" of R. pomonella lay their eggs on hawthorns OR apples. Apples occur within the range of hawthorns, so divergence between apple flies and hawthorn flies could be the first step in sympatric speciation. Choose the evidence that supports that R. pomonella is undergoing sympatric speciation. Check all that apply.

Accepted Answer

Apple flies and hawthorn flies mating within their own groups and emerging at different times suggest reproductive isolation, which is a key factor in sympatric speciation.

Question 6

A virgin pine forest covers a valley, and one of the inhabitants is a red squirrel species. A large volcanic eruption occurs and separates the valley with a huge lava flow that the squirrels cannot cross, thus producing two isolated populations of squirrels. What change needs to occur for the two populations of squirrels to become separate species?

Accepted Answer

Reproductive isolation is necessary for the two populations to become separate species, as it prevents gene flow between them, leading to genetic divergence.

Question 7

Adaptive radiation is best described as the

Accepted Answer

Adaptive radiation refers to the process where a single ancestral species rapidly diversifies into a variety of new forms that are adapted to different environments or niches, resulting in closely related species.

Question 8

Lake Victoria is famous for its variety of cichlid fishes. In fact, they offer the most diverse assembly of vertebrates presently known to science. One trait that scientists have focused on as one possible reason for their adaptability is

Accepted Answer

Cichlid fishes have a second set of jaws in their throats, known as pharyngeal jaws, which allows them to process a wide variety of food types and contributes to their adaptability and diversity.

Question 9

Indicate which examples would be considered different species under the Biological Species Concept. Check all that apply.

Accepted Answer

The answer of Indicate which examples would be considered different...

Question 10

Several new tetraploid species of plant known as the salsifies have arisen in western North America. These new species arose from diploid species that went through the process of allopolyploidy. This mode of speciation is known as ________ and it occurs _______.

Accepted Answer

Allopolyploidy is a form of sympatric speciation where new species arise almost instantaneously due to the combination of chromosomes from different species.

Question 11

Which statements about the Lake Victoria cichlid fishes are true? Check all that apply.

Accepted Answer

The adaptive radiation of the Lake Victoria cichlid fishes was very rapid and took place during the last 200,000 years (A). The adaptive radiation of the Lake Victoria cichlids may have resulted from a key evolutionary innovation (B). Many of the Lake Victoria cichlids have very specialized adaptations that allow them to occupy diverse habitats within the lake (E).

Question 12

Which statements about the adaptive radiation of New Zealand alpine buttercups are true? Check all that apply.

Accepted Answer

The answer of Which statements about the adaptive radiation of...

Question 13

Which statements about gradualism and punctuated equilibrium are true? Check all that apply.

Accepted Answer

Punctuated equilibrium proposes that species remain stable for long periods, with significant changes occurring during short, rapid events of speciation. Gradualism suggests slow, continuous change not necessarily linked to speciation events.

Question 14

Two species regularly come into contact and form hybrids that have higher fitness than either of the parental species. What are the possible consequences of regular hybridization between these species? Check all that apply.

Accepted Answer

The formation of hybrids with higher fitness can lead to the evolution of a third species (A), the extinction of the parental species if hybrids outcompete them (C), and increased gene flow between the parental species as hybrids may backcross with them (D). Reinforcement of prezygotic isolating mechanisms (B) is unlikely because hybrids have higher fitness, reducing the selective pressure for such mechanisms.

Question 15

NASA Scientists send a small population of dogs to a new planet in order to test if it will be hospitable for human colonization. Through a random lottery, only Great Dane and St. Bernard dog breeds are sent, and the resulting population consists of tall, longhaired dogs. After 100 years these dogs return to earth and are no longer able to mate with earth dogs. This scenario is an example of

Accepted Answer

The dogs were geographically isolated on a new planet, leading to allopatric speciation. The inability to mate with Earth dogs suggests genetic drift played a role in their evolution.

Question 16

Scientists investigating speciation in fruit flies divided a single population of flies into separate populations that each lived in their own cage on one of two food sources: maltose-based food or starch-based food. After several generations, the flies' mate preference was tested, and it was found that flies strongly preferred to mate with other flies that were raised on the same food source. This results suggests that

Accepted Answer

The experiment suggests that the selection pressure from different food sources led to the evolution of mate preferences, which are a form of reproductive isolating mechanism. This indicates that the flies evolved to prefer mates from the same food source, indirectly leading to reproductive isolation.

Question 17

The most famous and well-studied mass extinction occurred at the end of the Cretaceous period (65 million years ago), at which time the dinosaurs and a variety of other terrestrial and aquatic organisms went extinct. Recent findings have supported the hypothesis that this extinction event was triggered when a large asteroid slammed into Earth. Which of the following could cause a global mass extinction following an asteroid strike? (Check all that apply)

Accepted Answer

The impact could trigger global forest fires and create a massive dust cloud, both of which would obscure the sun, leading to a decrease in photosynthesis and a collapse of ecosystems.

Question 18

Scientists estimate that as much as one-fourth of all species will become extinct in the near future, a rate of extinction not seen on Earth since the Cretaceous mass extinction. How are humans contributing to this mass extinction? (Check all that apply)

Accepted Answer

Humans contribute to mass extinction primarily through climate change and habitat destruction, which disrupt ecosystems and threaten species survival.

Quiz 19: The Origin of Species