Question 1

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

Accepted Answer

D

Question 2

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?

Accepted Answer

Habitat isolation refers to the fact that two closely related species may occupy different habitats within the same region, and thus may never have the chance to come into contact with each other. In this case, the insect species living on goldenrod plants and the one living on autumn daisies are separated by the difference in the plants they inhabit, even though they could potentially interbreed if given the opportunity.

Question 3

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.

Accepted Answer

The description given fits that of allopatric speciation, where a population becomes geographically isolated from the parent species and evolves independently, leading to the development of reproductive barriers between the two groups.

Question 4

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 ________ ________ reproductive barrier.

Accepted Answer

Behavioral courtship rituals are prezygotic reproductive barriers because they prevent mating between individuals of different species before fertilization can occur. Mechanical barriers involve physical incompatibilities between reproductive structures, temporal barriers involve differences in mating times, and gametic barriers involve incompatibilities between sperm and egg. Postzygotic barriers occur after fertilization and either prevent the development of viable offspring or reduce their fitness.

Question 5

Which of the following would a biologist describe as microevolution?

Accepted Answer

Microevolution refers to a change in the gene pool of a population from one generation to the next. This can occur through natural selection, genetic drift, or gene flow. The other options listed (A, B, and C) refer to macroevolutionary processes, such as the formation of new species or major evolutionary changes within a taxon.

Question 6

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

Accepted Answer

The morphological species concept relies on comparing the physical characteristics of organisms, not their DNA sequences.

Question 7

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?

Accepted Answer

Temporal isolation occurs when species breed at different times or seasons. In this case, one species mates at dusk while the other mates at dawn, preventing interbreeding between the two species.

Question 8

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

Accepted Answer

The scenario describes the initial separation of the snail populations due to uplift and formation of a mountain range, which is an example of allopatric speciation. When the populations are brought back together and cannot produce viable offspring, this is an example of reproductive isolation, which is often a common result of allopatric speciation. The fact that the hybrid offspring are all sterile suggests that there has been significant genetic divergence between the two populations, leading to their inability to mate successfully.

Question 9

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

Accepted Answer

Reduced hybrid fertility refers to when two species mate and produce offspring that are sterile or have reduced fertility. This is different from gametic isolation, where the gametes of two different species are unable to unite to form a zygote. Reduced hybrid viability refers to when the offspring of two species have reduced survival rates or are unable to develop properly. Hybrid breakdown refers to when the first-generation hybrids of two species are fertile, but their offspring (the second generation) are sterile or have reduced fertility.

Question 10

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?

Accepted Answer

The type of reproductive barrier described in this scenario is mechanical isolation. The difference in the length and width of the flower tubes prevents effective pollination between the two species, even though they could potentially interbreed. Habitat isolation refers to geographical or ecological barriers that prevent species from encountering each other. Behavioral isolation involves differences in mating behaviors or preferences between species. Gametic isolation occurs when gametes from two different species are unable to unite and produce viable offspring.

Question 11

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?

Accepted Answer

Behavioral isolation occurs when two species have differences in behavior or courtship rituals that prevent them from mating. In this case, the females of one moth species are producing pheromones that are not attractive to males of the other species, leading to behavioral isolation.

Question 12

The biological species concept is

Accepted Answer

The biological species concept is sometimes difficult to apply even for present sexual organisms and useless for asexual organisms and fossils. This is because it relies on reproductive isolation, which may not always be easy to observe or determine. Additionally, asexual organisms and fossils do not have a clear definition of what constitutes a "species" based on reproductive isolation.

Question 13

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

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 14

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

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. This means that two populations must be able to mate and produce offspring that are capable of producing their own viable, fertile offspring for them to be considered part of the same species. Options A, B, and C all focus on different factors that may prevent or complicate mating between populations, but they do not address the fundamental requirement of producing fertile offspring.

Question 15

Which provides the most general and correct description of the idea of a reproductive barrier?

Accepted Answer

A reproductive barrier is a biological feature that prevents interbreeding between two species. This includes physical, genetic, or behavioral differences that prevent successful mating or the production of viable offspring. Option B provides the most general and correct definition of a reproductive barrier. Options A,C, and D also provide aspects of reproductive barriers, but do not encompass the full definition of the term.

Question 16

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.

Accepted Answer

This is an example of temporal isolation because the two species have different timing of their reproductive cycles (the release of pollen) which prevents them from mating with each other.

Question 17

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

Accepted Answer

The phenomenon where two species occasionally mate and produce zygotes that are not viable due to incompatible genes is known as reduced hybrid viability. This means that the offspring may not be able to develop properly and may die before reaching maturity. Gametic isolation is the prevention of fusion of gametes from different species, reduced hybrid fertility refers to the inability of hybrids to produce viable offspring, and hybrid breakdown refers to the decreased fitness of the offspring of hybrids over generations.

Question 18

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?

Accepted Answer

Gametic isolation occurs when gametes (sperm and egg) of different species are not compatible and cannot fertilize each other. In the case of the sea cucumbers, the proteins on their surfaces prevent cross-fertilization despite frequently coming into contact. This is a form of gametic isolation.

Question 19

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

Accepted Answer

The biological species concept defines a species as a group of organisms that can interbreed in nature and produce viable and fertile offspring. This criterion is based on the idea that members of a species share a common gene pool, and therefore their genetic material can be exchanged through interbreeding. Physical similarity, common ancestry, and ecological roles may not necessarily indicate a shared gene pool, and hence do not form the basis of the biological species concept.

Question 20

Speciation, or the formation of new species, is

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.

Quiz 14: The Origin of Species