Question 1

Two species that occasionally mate and produce zygotes, but that have incompatible genes that prevent the resulting embryo from developing, are affected by
A) gametic isolation.
B) reduced hybrid fertility.
C) reduced hybrid viability.
D) behavioral isolation.

Accepted Answer

Reduced hybrid viability refers to the occurrence of mating between two species that occasionally produce viable zygotes that ultimately fail to develop due to incompatible genes. This results in reduced hybrid viability, as the resulting embryo is unable to develop normally and dies before reaching maturity.

Question 2

Two populations of organisms belong to the same biological species when they
A) cannot mate with each other because mating occurs at different times.
B) use different types of behaviors or physical features to attract mates.
C) have anatomical features that make it difficult for organisms from the two populations to mate with one another.
D) encounter each other, mate, and produce viable, fertile offspring under natural conditions.

Accepted Answer

The biological species concept defines a species as a group of organisms that can interbreed and produce viable, fertile offspring under natural conditions. Therefore, option D is the correct choice because it describes the key component of this concept, which is reproductive compatibility. Options A, B, and C describe factors that can contribute to reproductive isolation, which can lead to the divergence of populations over time, but they do not necessarily define a species.

Question 3

The Monterey pine and the Bishop's pine inhabit some of the same areas of central California. The Monterey pine releases pollen in February, while the Bishop's pine does so in April. This is an example of ________ isolation.
A) postzygotic
B) temporal
C) habitat
D) mechanical

Accepted Answer

This is an example of temporal isolation because the two species have different timing for their pollen release.

Question 4

Which of the following types of reproductive barriers separates two species of sea cucumbers whose sperm and eggs often bump into each other but do not cross-fertilize because of incompatible proteins on their surfaces?
A) temporal isolation
B) habitat isolation
C) mechanical isolation
D) gametic isolation

Accepted Answer

The type of reproductive barrier described is gametic isolation, in which sperm and egg of different species do not fuse because of incompatible molecules on their surfaces. This is the case for the sea cucumbers in the scenario. Temporal isolation refers to species that breed at different times, habitat isolation refers to species that live in different environments, and mechanical isolation refers to species that cannot mate or transfer sperm successfully due to physical incompatibilities.

Question 5

The biological species concept is
A) applicable to all forms of life, past and present.
B) applicable to all present life-forms but not to fossil organisms whose reproductive behavior cannot be observed.
C) easy to apply to all present sexually reproducing organisms but harder to apply to asexual organisms and fossils.
D) sometimes difficult to put into practice even for present sexual organisms and useless for asexual organisms and fossils.

Accepted Answer

The biological species concept is sometimes difficult to put into practice even for present sexual organisms and useless for asexual organisms and fossils. While the concept is straightforward (groups of organisms that can interbreed and produce viable offspring are considered to be the same species), in practice it can be challenging to determine whether two groups of organisms meet this criterion. Additionally, the concept does not apply to asexual organisms or to fossils, where reproductive behavior cannot be observed.

Question 6

Which of the following would a biologist describe as microevolution?
A) the formation of new species
B) the extinction of species
C) dramatic biological changes, such as the origin of flight, within a taxon
D) a change in the gene pool of a population from one generation to the next

Accepted Answer

Microevolution refers to small-scale evolutionary changes that occur within a population, such as changes in the frequency of alleles or traits from one generation to the next. The formation of new species (speciation) and the extinction of species are examples of macroevolution, while the origin of flight within a taxon would likely involve multiple evolutionary changes and could also be categorized as macroevolution.

Question 7

In which of the following situations would speciation be most likely to occur?
A) A population of juniper shrubs is split in two by a canyon. Every year, strong winds carry a small amount of the shrubs' pollen across the canyon.
B) A Japanese mollusk species whose larvae are often carried from port to port in ship bilge (waste) water now flourishes in San Francisco Bay, a busy commercial port.
C) Bighorn sheep occupy mountains from Canada to Death Valley in Southern California, interbreeding all the way. The populations at the two ends of the range live in very different environments.
D) Seven monkeys escape from an enclosure. To everyone's surprise, they establish a small but viable population, coexisting successfully with humans in a partly suburban environment very different from their native African habitat.

Accepted Answer

The answer of In which of the following situations would...

Question 8

Which of the following types of reproductive barriers separates a pair of species that could interbreed but for the fact that one mates at dusk and the other at dawn?
A) temporal isolation
B) habitat isolation
C) behavioral isolation
D) mechanical isolation

Accepted Answer

Temporal isolation is a type of reproductive barrier that occurs when two species reproduce at different times or seasons. In this scenario, the species mate at different times of the day, making it difficult for them to interbreed. This type of isolation is behavioral in nature as it involves differences in the behavior of the species during the mating season. Habitat isolation refers to species occurring in different habitats, mechanical isolation refers to differences in reproductive structures, and behavioral isolation involves differences in mating behavior.

Question 9

Which of the following types of reproductive barriers separates a pair of moth species that could interbreed but for the fact that the females' mating pheromones are not attractive to the males of the other species?
A) temporal isolation
B) behavioral isolation
C) mechanical isolation
D) gametic isolation

Accepted Answer

Behavioral isolation refers to the separation of species due to differences in mating behaviors or preferences. In this case, the females' mating pheromones are not attractive to the males of the other species, creating a barrier to interbreeding. Temporal isolation refers to species breeding at different times, mechanical isolation refers to physical incompatibility of reproductive structures, and gametic isolation refers to the inability of sperm and egg to unite successfully.

Question 10

Which of the following statements regarding the definition of species is false?
A) The ecological species concept identifies species in terms of their ecological niches.
B) The phylogenetic species concept defines a species as a set of organisms that shares a common ancestor and forms one branch on the tree of life.
C) The morphological species concept relies upon comparing the DNA sequences of organisms.
D) Under the biological species concept, the gap between species is maintained by reproductive isolation.

Accepted Answer

The morphological species concept relies upon comparing the physical characteristics and traits of organisms, rather than their DNA sequences.

Question 11

Uplift and formation of a mountain range divide a freshwater snail species into two isolated populations. Erosion eventually lowers the mountain range and brings the two populations together again, but when they mate, the resulting hybrids all produce sterile young. This scenario is an example of
A) sympatric speciation.
B) allopatric speciation.
C) incomplete speciation.
D) diversifying speciation.

Accepted Answer

This scenario describes the process of allopatric speciation, where a geographical barrier (mountain range) divides a species into two isolated populations, leading to genetic divergence and the development of reproductive isolation. When the populations come back into contact, they are unable to reproduce and produce viable offspring, indicating the formation of separate species.

Question 12

Under the biological species concept, a species is a group of organisms that
A) are physically similar.
B) share a recent common ancestor.
C) live together in a location and carry out identical ecological roles.
D) have the potential to interbreed in nature and produce fertile offspring.

Accepted Answer

The biological species concept defines a species based on the ability to interbreed and produce fertile offspring. Physical similarity or ecological roles are not defining factors, and while a common ancestor may be a feature of a species, it is not the sole defining characteristic.

Question 13

Frequently, a group of related species will each have a unique courtship ritual that must be performed correctly for both partners to be willing to mate. Such a ritual constitutes a ________ and ________ reproductive barrier.
A) mechanical; postzygotic
B) behavioral; prezygotic
C) temporal; prezygotic
D) gametic; postzygotic

Accepted Answer

A courtship ritual is a type of behavioral isolation, which is a prezygotic reproductive barrier. This means that it prevents mating from occurring in the first place, rather than preventing successful reproduction after mating has occurred. The other options listed either do not accurately describe a courtship ritual or describe a different type of reproductive barrier.

Question 14

Diane Dodd raised different fruit fly populations on different food sources. She found that after about 40 generations the evolution of reproductive isolation was under way. The mechanism of evolution responsible for this was
A) natural selection.
B) genetic drift.
C) gene flow.
D) hybridization.

Accepted Answer

Over 40 generations, the fruit fly populations evolved reproductive isolation, which means they were becoming genetically distinct from one another, reducing their ability to interbreed. This process is likely due to natural selection, as individuals with genetic traits that prevent interbreeding with other populations would have higher fitness and thus be more likely to survive and reproduce. Genetic drift and gene flow can also contribute to evolutionary changes, but are less likely to be responsible for the observed reproductive isolation in this case. Hybridization typically involves the interbreeding of two different species or populations, and is therefore not relevant to the scenario presented.

Question 15

Which of the following types of reproductive barriers separates two flowering plant species that could interbreed but for the fact that one has a deep flower tube and is pollinated by bumblebees whereas the other has a short, narrow flower tube and is pollinated by honeybees?
A) habitat isolation
B) behavioral isolation
C) mechanical isolation
D) gametic isolation

Accepted Answer

The deep flower tube and short, narrow flower tube represent a mechanical isolation barrier, as the physical structure of the flowers prevents interbreeding between the two species. The other types of reproductive barriers listed do not directly relate to physical differences in the flowers.

Question 16

Speciation, or the formation of new species, is
A) a form of microevolution.
B) responsible for the diversity of life.
C) necessary for natural selection and adaptation.
D) an event that has occurred only a few times in the history of the planet.

Accepted Answer

Speciation is responsible for the diversity of life on Earth, as it creates new species with unique traits and adaptations. While it is a form of evolution, it is considered a macroevolutionary process as it involves the formation of new species, rather than changes within a population. Speciation has occurred many times throughout the history of the planet, and continues to occur today.

Question 17

Two species interbreed occasionally and produce vigorous, fertile hybrids. When the hybrids breed with each other or with either parent species, however, the offspring are feeble or sterile. These species are affected by
A) gametic isolation.
B) reduced hybrid fertility.
C) reduced hybrid viability.
D) hybrid breakdown.

Accepted Answer

Hybrid breakdown occurs when the first-generation hybrids are viable and fertile, but when these hybrids mate with each other or with either parent species, their offspring are feeble or sterile. This situation matches the scenario described.

Question 18

Two species that sometimes mate and produce vigorous but sterile offspring are affected by
A) gametic isolation.
B) reduced hybrid fertility.
C) reduced hybrid viability.
D) hybrid breakdown.

Accepted Answer

Reduced hybrid fertility refers to the situation where two different species sometimes mate and produce offspring that are sterile. This is different from reduced hybrid viability, which refers to offspring that are not capable of surviving to reproductive age. Gametic isolation occurs when the gametes of two different species are incompatible and cannot form a zygote. Hybrid breakdown occurs when the first-generation hybrids are viable and fertile, but their offspring (second-generation hybrids) are feeble or sterile.

Question 19

The geographic isolation of a population from other members of the species and the subsequent evolution of reproductive barriers between it and the parent species describes ________ speciation.
A) punctuated
B) sympatric
C) allopatric
D) biogeographic

Accepted Answer

The description provided matches the process of allopatric speciation, which involves geographic isolation of a population leading to the evolution of reproductive barriers. Punctuated speciation refers to a pattern of relatively rapid evolution separated by long periods of stability, and sympatric speciation occurs without geographic isolation. Biogeographic speciation is not a commonly used term in evolutionary biology.

Question 20

Which of the following types of reproductive barriers separates a pair of insect species that could interbreed but for the fact that one lives on goldenrod plants and the other on autumn daisies in the same general area?
A) temporal isolation
B) habitat isolation
C) behavioral isolation
D) gametic isolation

Accepted Answer

Habitat isolation is the type of reproductive barrier that separates a pair of insect species that could interbreed but for the fact that one lives on goldenrod plants and the other on autumn daisies in the same general area. This is because the insects are adapted to mating and reproducing in their respective habitats and may not encounter each other for mating.

Quiz 14: The Origin of Species

Two species that occasionally mate and produce zygotes, but that have incompatible genes that prevent the resulting embryo from developing, are affected by

Two populations of organisms belong to the same biological species when they

The Monterey pine and the Bishop's pine inhabit some of the same areas of central California. The Monterey pine releases pollen in February, while the Bishop's pine does so in April. This is an example of ________ isolation.

Which of the following types of reproductive barriers separates two species of sea cucumbers whose sperm and eggs often bump into each other but do not cross-fertilize because of incompatible proteins on their surfaces?

The biological species concept is

Which of the following would a biologist describe as microevolution?

In which of the following situations would speciation be most likely to occur?

Which of the following types of reproductive barriers separates a pair of species that could interbreed but for the fact that one mates at dusk and the other at dawn?

Which of the following types of reproductive barriers separates a pair of moth species that could interbreed but for the fact that the females' mating pheromones are not attractive to the males of the other species?

Which of the following statements regarding the definition of species is false?

Uplift and formation of a mountain range divide a freshwater snail species into two isolated populations. Erosion eventually lowers the mountain range and brings the two populations together again, but when they mate, the resulting hybrids all produce sterile young. This scenario is an example of

Under the biological species concept, a species is a group of organisms that

Frequently, a group of related species will each have a unique courtship ritual that must be performed correctly for both partners to be willing to mate. Such a ritual constitutes a and reproductive barrier.

Diane Dodd raised different fruit fly populations on different food sources. She found that after about 40 generations the evolution of reproductive isolation was under way. The mechanism of evolution responsible for this was

Which of the following types of reproductive barriers separates two flowering plant species that could interbreed but for the fact that one has a deep flower tube and is pollinated by bumblebees whereas the other has a short, narrow flower tube and is pollinated by honeybees?

Speciation, or the formation of new species, is

Two species interbreed occasionally and produce vigorous, fertile hybrids. When the hybrids breed with each other or with either parent species, however, the offspring are feeble or sterile. These species are affected by

Two species that sometimes mate and produce vigorous but sterile offspring are affected by

The geographic isolation of a population from other members of the species and the subsequent evolution of reproductive barriers between it and the parent species describes ________ speciation.

Which of the following types of reproductive barriers separates a pair of insect species that could interbreed but for the fact that one lives on goldenrod plants and the other on autumn daisies in the same general area?