Question 1

A pet store puts both Norway rats (Rattus norvegicus)and black rats (Rattus rattus)in the same cage. If mating occurs, the pregnancy will not succeed because the embryos fail to develop properly. This is an example of:

Accepted Answer

Hybrid inviability occurs when hybrids between two different species are sterile or have reduced fertility due to genetic incompatibilities, resulting in failure of offspring development. This is seen in the case of Norway and black rats interbreeding, resulting in unsuccessful pregnancy due to embryo developmental issues. Therefore, the correct answer is B - hybrid inviability.

Question 2

Since the Pleistocene ice age, deserts have been gradually forming in the southwestern United States. As the original lakes and rivers of this area shrank into isolated streams, ponds, and springs, the fishes living in them developed a strong potential for:

Accepted Answer

The formation of deserts in the southwestern United States led to the isolation of fishes in small bodies of water, which could lead to speciation over time as different populations adapt to their specific environments.

Question 3

Lions and tigers can interbreed and produce offspring called tiglons or ligers, which have normal life spans but are sterile. Lions and tigers remain isolated genetically because of:

Accepted Answer

Tiglons or ligers have normal lifespans but are sterile due to hybrid infertility, which prevents lions and tigers from interbreeding and remaining genetically isolated. Hybrid inviability, mechanical incompatibility, behavioral isolation, and heterozygote disadvantage apply to other forms of reproductive isolation.

Question 4

Interbreeding two different species of lovebirds produces offspring that are unable to build a nest after they mature because they lack the appropriate innate knowledge needed to carry the nesting materials and build a nest. This limits genetic mixing between the species due to:

Accepted Answer

The inability of interbred lovebird offspring to build a nest indicates that there is behavioral isolation between the two species. They lack the appropriate innate knowledge needed to carry the nesting materials and build a nest, which inhibits genetic mixing between the two species. Hybrid inviability refers to the fact that some hybrids may be unable to survive to reproductive age, which is not applicable in this scenario. Ecological and mechanical incompatibility and geographic isolation are also not relevant factors in this situation.

Question 5

Two species of squirrels live on either side of the Grand Canyon. It is believed that a long time ago, before being separated by the canyon, they were the same species. This is an example of:

Accepted Answer

This is an example of allopatric speciation, which occurs when a physical barrier (in this case, the Grand Canyon) separates a population into two or more geographically isolated groups that eventually evolve into separate species.

Question 6

Temporal isolation is an example of:

Accepted Answer

Temporal isolation refers to differences in breeding times or seasonal preferences that prevent individuals of different species from mating with each other. It is a premating isolating mechanism because it occurs before mating takes place. Postmating isolating mechanisms, on the other hand, include things like hybrid inviability or infertility that prevent successful reproduction after mating has occurred.

Question 7

The Great Dane and the chihuahua are both domestic dogs (the same species), but mating between them is limited because of:

Accepted Answer

The difference in size between a Great Dane and a chihuahua is vast, and their reproductive structures are not compatible due to the significant size difference. This creates mechanical incompatibility and prevents successful mating. Hybrid infertility and inviability refer to situations where hybrid offspring are either sterile or unable to survive, respectively, which is not applicable in this case. Behavioral and geographic isolation refer to interbreeding barriers that result from differences in behavior and location, respectively, which are also not relevant here.

Question 8

Horses and donkeys can mate successfully to produce mules, which are always sterile. Which genetic isolating mechanism prevents horses and donkeys from becoming a single species?

Accepted Answer

Horses and donkeys can produce offspring, but the resulting mules are always sterile. This is an example of hybrid infertility, which prevents horses and donkeys from becoming a single species despite their ability to interbreed. Hybrid inviability refers to hybrids that do not develop to maturity or are not viable, while mechanical isolation, behavioral isolation, and temporal isolation are prezygotic isolating mechanisms that prevent mating or fertilization from occurring in the first place.

Question 9

Ligers, the offspring from the mating of a lion and a tiger, are sterile. This is an example of:

Accepted Answer

Ligers are an example of hybrid infertility, which occurs when the offspring of two different species are sterile, unable to produce offspring themselves. This is due to differences in the number of chromosomes and genetic incompatibility between the two parent species. The other options (geographic isolation, gametic incompatibility, mechanical incompatibility, and behavioral isolation) do not apply to this scenario.

Question 10

Where would a researcher most likely find examples of allopatric speciation?

Accepted Answer

Allopatric speciation occurs when populations of a species become geographically isolated from each other. A mountain range with steep valleys and turbulent rivers would likely lead to geographic isolation of populations, therefore providing a high likelihood of examples of allopatric speciation.

Question 11

When offspring are infertile after breeding occurs between individuals of different species, the genetic identities of the two populations are protected by:

Accepted Answer

Hybrid infertility is a post-zygotic barrier that prevents the offspring of two different species from producing viable, fertile offspring. This helps protect the genetic identity of the two populations involved by preventing the mixture of their genetic material. The other choices (mechanical incompatibility, temporal isolation, behavioral isolation, and genetic isolation) are pre-zygotic barriers that prevent successful mating or fertilization between individuals of different species, but they do not necessarily guarantee that the genetic identities of the populations are protected.

Question 12

Gametic incompatibility is an example of:

Accepted Answer

Gametic incompatibility is a postmating isolating mechanism because it occurs after mating has taken place, preventing successful fertilization or development.

Question 13

What happens when two populations become geographically separated from each other and then genetic divergence occurs?

Accepted Answer

Allopatric speciation occurs when two populations become geographically separated from each other and genetic divergence occurs. Over time, the populations accumulate different mutations and adaptations, which can lead to the development of new species.

Question 14

When the pollen of one plant species will not germinate on the flower of another species, it is an example of:

Accepted Answer

When the pollen of one plant species will not germinate on the flower of another species, it is known as gametic incompatibility. This occurs because the sperm from one species cannot fuse with the egg of another species. This is different from temporal isolation, which is when two species reproduce at different times of day/year; hybrid inviability, which is when a hybrid offspring fails to develop properly and dies; hybrid infertility, which is when hybrid offspring are sterile; and hybrid vigor, which is when hybrid offspring are more vigorous than either parent species.

Question 15

Crossing a zebra with a horse produces sterile offspring. This is an example of:

Accepted Answer

Hybrid infertility refers to the inability of offspring from two different species to produce viable offspring of their own. This is seen in the sterile offspring resulting from the cross between a zebra and a horse.

Question 16

The Kaibab squirrel lives on the north side of the Grand Canyon, and the Abert squirrel lives on the south side. Even though these two populations are only miles apart, their gene pools are kept isolated by:

Accepted Answer

The Kaibab and Abert squirrels are geographically isolated by the Grand Canyon, which prevents interbreeding between the two populations. This isolation prevents gene flow and maintains genetic differences between the two populations.

Question 17

If a hybrid is unable to produce sperm because meiosis does not proceed correctly, gene flow between the populations is restricted by:

Accepted Answer

Hybrid infertility refers to the inability of hybrids to produce viable offspring, which restricts gene flow between populations due to the lack of successful reproduction. Gametic isolation refers to the inability of sperm or egg cells of one species to fertilize the other, which would not be the case for this particular hybrid. Ecological isolation and temporal isolation relate to differences in habitat or timing of mating, respectively, and would not be relevant in this scenario. Hybrid viability refers to the survival and development of hybrid offspring, which is not affected by the inability to produce viable sperm.

Question 18

There are currently many similar-looking but different species on either side of the Isthmus of Panama. They most likely resulted from:

Accepted Answer

The most likely explanation for the creation of similar-looking but different species on either side of the Isthmus of Panama is allopatric speciation. This occurs when populations become geographically separated and then diverge genetically over time due to different selective pressures and genetic drift. With the formation of the Isthmus of Panama, this geographic separation would have occurred, leading to separate evolution of species on either side.

Question 19

When some hybrid organisms do not live long, it is an example of:

Accepted Answer

Hybrid inviability occurs when hybrid organisms do not survive or live long due to genetic incompatibility between the two parent species. This is different from hybrid infertility, where hybrid organisms are able to survive but cannot reproduce, and from hybrid vigor, where hybrid organisms have increased fitness compared to their parent species. Temporal isolation and gametic incompatibility are other mechanisms of reproductive isolation that prevent interbreeding between different species.

Question 20

When two organisms reach sexual maturity at different times, it is an example of:

Accepted Answer

Temporal isolation is a mechanism of reproductive isolation where two species or populations reproduce at different times. This can lead to the two populations never having the opportunity to mate and produce viable offspring.

Quiz 16: The Origin of Species

A pet store puts both Norway rats (Rattus norvegicus) and black rats (Rattus rattus) in the same cage. If mating occurs, the pregnancy will not succeed because the embryos fail to develop properly. This is an example of: