Question 1

Before the cultivation of the apple tree, apple maggot flies laid their eggs exclusively on the fruit of Hawthorne trees. As apple orchards became more prominent, apple maggot flies began to lay their eggs on both the fruit of the Hawthorne tree and the fruit of cultivated apple trees. Now, apple maggot flies that live on apple trees mate and lay their eggs at different times of the year than apple maggot flies that live on Hawthorne trees. Is this an example of reproductive isolation?

Accepted Answer

The fact that the apple maggot flies that live on apple trees and those that live on Hawthorne trees mate and lay their eggs at different times of the year suggests that they have a behavioral prezygotic barrier that prevents their gametes from encountering each other. This is an example of reproductive isolation, as the two populations have lost the ability to interbreed due to differences in their behavior, which prevents the formation of hybrid individuals. The other answer choices are incorrect because they do not accurately reflect the nature of the reproductive isolation exhibited by these fly populations.

Question 2

In the figure below, two populations of one species of fruit flies were raised for several generations on different nutrients (starch and maltose). Then the members of the two populations were reintroduced and the mating frequencies of flies from the two different populations were recorded. Which of the following is true?

Accepted Answer

The fact that male flies are more likely to mate with female flies that were raised on the same medium suggests that the two populations are in the early stages of reproductive isolation. However, this does not necessarily mean that speciation has occurred because some mating is still taking place between individuals from the different populations. Additionally, there is no evidence provided to support choices C or D.

Question 3

Bacteria reproduce asexually so scientists classify them based on

Accepted Answer

Bacteria reproduce asexually, so they cannot be classified based on reproductive isolation, which is a key aspect of the biological species concept. Instead, scientists use the morphological species concept, which defines species based on physical characteristics such as shape, size, and color. Alternatively, they may use other factors such as ecological niche or genetic relatedness. However, the morphological species concept is the most commonly used method for bacterial classification.

Question 4

A large population of animals is split in two by a physical barrier. Over time, the genetic makeup of the two resulting populations becomes more and more different, until each population becomes a separate species. This is an example of

Accepted Answer

This scenario describes allopatric speciation, which occurs when populations are geographically isolated and evolve independently. Over time, genetic differences accumulate between the populations, leading to the development of distinct species. Sympatric speciation, on the other hand, occurs within a single geographic location without physical separation. Genetic drift and natural selection are mechanisms of evolution that can contribute to speciation, but neither is specific to this scenario.

Question 5

Which of the following is not an example of a prezygotic barrier?

Accepted Answer

Option C describes a postzygotic barrier where the hybrid offspring is reproductively sterile, meaning it cannot produce viable gametes or offspring. Prezygotic barriers occur before fertilization, such as in options A, B, and D, where two populations are unable to mate due to temporal or behavioral differences, physical incompatibilities, or differences in habitats.

Question 6

Speciation

Accepted Answer

Geographic isolation can lead to the development of reproductive isolation, which is a key factor in speciation. This occurs when a population is physically separated from a larger population, leading to different genetic pressures and potentially the development of unique traits or behaviors that prevent interbreeding with the original population. Speciation can also occur through other factors, such as genetic mutations or changes in selective pressures, but geographic isolation is a common mechanism.

Question 7

Populations within a species are connected by

Accepted Answer

Populations within a species are connected by gene flow which is the transfer of genes from one population to another. This genetic exchange helps to maintain genetic diversity within a species and prevents populations from becoming too genetically different from one another.

Question 8

The red-breasted nuthatch and the white-breasted nuthatch are similar in appearance and, in many regions of the United States, their ranges overlap. The two organisms do not interbreed. Based on this information, red-breasted and white-breasted nuthatches are

Accepted Answer

Red-breasted and white-breasted nuthatches are considered to be different species because they do not interbreed, despite having similar appearances and overlapping ranges.

Question 9

Which of the following is an example of reproductive isolation?

Accepted Answer

The answer of Which of the following is an example...

Question 10

Two species live in the same area but breed in different parts of their habitat. These species are

Accepted Answer

The answer of Two species live in the same area...

Question 11

Geographic isolation limits the _____ between populations of a species.

Accepted Answer

Gene flow is the movement of genes from one population to another. Geographic isolation prevents or limits the movement of genes between populations, leading to increased genetic differences over time. Therefore, gene flow is limited by geographic isolation.

Question 12

Using reproductive isolation as a method of defining a species is not useful for

Accepted Answer

Reproductive isolation cannot be observed in organisms known only from fossils.

Question 13

Which of the following is an example of a prezygotic barrier that can isolate two species living in the same geographic area?

Accepted Answer

Prezygotic barriers occur before the formation of a zygote, or fertilized egg. Option A suggests that there is no barrier to mating, while option B suggests there may be a behavioral barrier. Option D suggests that hybrids are produced, which may still be able to interbreed with the parent species. Option C, however, describes a situation where the gametes of two different orchid species are unable to fuse, preventing fertilization from occurring and therefore isolating the two species.

Question 14

For two populations to accumulate enough genetic differences to cause speciation, the factors that promote these differences

Accepted Answer

Gene flow can act as a homogenizing force that counters the accumulation of genetic differences between populations, which is necessary for speciation to occur. Therefore, for speciation to occur, the factors promoting genetic differences must outweigh the effects of gene flow.

Question 15

The fossils of two adult birds are found in a nest containing several fossilized eggs. Physically, the bird fossils look very different. What are scientists most likely to use to classify these species?

Accepted Answer

Since the physical characteristics of the birds are different, scientists are most likely to use the morphological species concept, which is based on observable physical traits, to classify these species.

Question 16

The primary difference between the prezygotic barriers and postzygotic barriers involved in reproductive isolation is that prezygotic barriers

Accepted Answer

Prezygotic barriers prevent fertilization from occurring, while postzygotic barriers occur after fertilization and prevent offspring from developing or being reproductively successful. Prezygotic barriers can include behavioral, temporal, mechanical, and ecological factors that prevent successful mating or fertilization from occurring. Postzygotic barriers, on the other hand, can involve a variety of developmental, genetic, or behavioral factors that decrease the fitness of hybrids or prevent them from producing viable offspring.

Question 17

Why have the two plant populations depicted in the diagram below become so different in the time they were separated by the ocean?

Accepted Answer

Over time, the populations on either side of the ocean adapted to different environmental conditions. This led to the development of distinct characteristics that caused them to become reproductively isolated. This means that they were no longer able to interbreed and exchange genetic material, which allowed for even greater divergence between the two populations. This is an example of allopatric speciation.

Question 18

Individuals of the same species generally

Accepted Answer

Individuals of the same species share many common physical and behavioral characteristics, which are inherited traits that are passed down from generation to generation. This is why they are considered members of the same species, because they are able to interbreed and produce viable and fertile offspring.

Question 19

Which of the following is an example of a postzygotic barrier?

Accepted Answer

A postzygotic barrier occurs after fertilization has taken place. Choice A refers to a prezygotic barrier. Choices C and D refer to behavioral or temporal isolation, which are also prezygotic barriers. Choice B is an example of a postzygotic barrier, as the zygote fails to develop properly, resulting in hybrid inviability or sterility.

Question 20

Great controversy exists regarding the "hobbits" of Flores Island. Which of the following arguments would not support the hypothesis that hobbits are the same species as modern humans?

Accepted Answer

The answer of Great controversy exists regarding the "hobbits" of...

Quiz 19: Speciation and the Origins of Biological Diversity