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CHAPTER 14

Terms in this set (49)

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.
B
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
D
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.
D
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.
D
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.
C
Which provides the most general and correct description of the idea of a reproductive barrier?
A) any feature (of geography, behavior, or morphology) that keeps one species from mating with another B) a biological difference between two species that prevents them from successfully interbreeding C) a geographic barrier that separates two species and prevents gene flow between them D) a difference in behavior that keeps two species from interbreeding
B
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.
D
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
A
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
B
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
B
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
C
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
D
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) hybrid breakdown.
D
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.
B
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.
D
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.
A) mechanical; postzygotic B) behavioral; prezygotic C) temporal; prezygotic D) gametic; postzygotic
B
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
B
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
C
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.
B
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.
D
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) mutation.
A
Diane Dodd's experiments using fruit flies demonstrated that
A) the evolution of reproductive barriers occurs much too slowly to produce measurable effects in the laboratory. B) new species can form in a single generation by the production of new reproductive structures. C) formation of a reproductive barrier between two populations is more likely if they experience and adapt to different environmental conditions. D) reproductive barriers usually are absolute: Either two populations are fully willing and able to interbreed, or they are strictly separated by a fully effective reproductive barrier.
C
When plants undergo allopatric speciation, an initial reproductive barrier is often
A) polyploidy. B) gametic isolation. C) temporal isolation. D) pollinator choice.
D
Speciation without geographic isolation is called ________ speciation.
A) sympatric B) allopatric C) incomplete D) diversifying
A
Organisms that possess more than two complete sets of chromosomes are said to be
A) haploid. B) polyploid. C) diploid. D) hybrids.
B
Most polyploid species arise from
A) a single diploid parent plant. B) a single triploid parent plant. C) a single tetraploid parent plant. D) the hybridization of two parent species.
D
When a tetraploid flower pollinates a diploid flower of the parental species, the resulting offspring will be
A) pentaploid and sterile. B) diploid and fertile. C) triploid and fertile. D) triploid and sterile
D
Sympatric speciation commonly occurs through ________ in plants but is more likely to occur through ________ in animals.
A) polyploidy; habitat differentiation and sexual selection B) habitat differentiation and sexual selection; polyploidy C) asexual reproduction; chromosome duplications D) self-pollination; polyploidy and other genetic mechanisms
A
Ancestral diploid wheat species had 2n = 14 chromosomes. What happened when two of these species hybridized?
A) They produced a viable, fertile hybrid species with 14 chromosomes. B) They produced a hybrid species that could not complete mitosis, so it did not develop properly. C) They produced a hybrid species with 14 chromosomes that was sterile because the chromosomes from the two different parent species did not pair up properly in meiosis. D) They produced a hybrid species with 28 chromosomes.
C
Which of the following statements about plant speciation and hybridization is false?
A) Plant biologists estimate that 80% of all living plant species are descended fro m ancestors that formed by polyploid speciation. B) Bread wheat is the ancestral diploid wheat plant. C) Modern plant geneticists use chemicals to induce meiotic and mitotic errors to try to create new hybrid plants with special qualities. D) Bread wheat grown widely today is the result of several hybridization events.
B
Which of the following statements about the Galápagos finches is false?
A) The Galápagos finch species differ in their feeding habitats. B) Each island in the Galápagos chain has one and only one isolated, unique species of Darwin's finch. C) Most speciation events of the Galápagos finches occurred when some finches made it to another island, evolved in isolation, and accumulated enough changes to become a new species. D) The evolution of the Galápagos finches is an excellent example of adaptive radiation.
B
The emergence of many diverse species from a common ancestor is called
A) adaptive radiation. B) gradualism. C) allopatric speciation. D) hybridization.
A
Which of the following would tend to promote adaptive radiation?
A) An organism has a very stable set of features and capabilities over long spans of evolutionary time. B) An organism colonizes an isolated area that is habitable but relatively devoid of life. C) An organism colonizes an area that already has a high level of existing species diversity. D) A single species goes extinct, but it has several competitors that quickly expand to assume its ecological roles.
B
A group of ants escaped from a picnic basket carried to the top of a mountain and thrived in this area where there were no other ants. Many years later descendants of these ants crawled into a picnic basket on the mountain and traveled back to the valley from which their ancestors had come. Which of these observations would cause you to conclude that the ants on top of the mountain had become a different species from those in the valley?
A) The mountain ants and valley ants were different colors. B) The mountain ants and valley ants were different sizes. C) The mountain ants ate different food than the valley ants. D) The mountain ants could not mate with the valley ants.
D
Two bird species overlap in a hybrid zone. They are isolated by a slight difference in the male songs and by the females' tendency to select males with the "correct" song. Hybrid offspring tend to have reduced fertility compared to either of the parent species. What effect might natural selection have in this situation?
A) Natural selection might favor males with less distinctive calls and/or females that are less "choosy." B) Natural selection might favor males with more distinctive calls and/or females that are more "choosy." As a result, the reproductive barrier between the two species could be reinforced. C) Natural selection could lead to the hybrid species taking over and eliminating the weaker parent species. D) Natural selection could lead to the stronger of the two species taking over and eliminating the other species.
B
In a hybrid zone, ________ can occur if the reproductive barrier between two species is weak, as seen among cichlids in the murky waters of modern Lake Victoria.
A) reinforcement B) fusion C) allopatric speciation D) reproductive isolation
B
The ________ suggests that speciation occurs in brief spurts.
A) adaptive model of the origin of species B) allopatric speciation model C) gradual model of the origin of species D) punctuated equilibrium model
D
The emergence of a new plant species over a brief period of time followed by a long period of little change is consistent with which of the following theories?
A) the gradual model of speciation B) allopatric speciation C) punctuated equilibrium D) adaptive radiation
C
One of the key contributions of the punctuated equilibrium model is that it helps explain
A) why transitional fossils are more common than Darwin would have predicted. B) why transitional fossils tend to be rare and certain common fossil species remain unchanged for long time spans. C) how new species arise from hybridization events. D) why large, widespread populations tend to be the ones that evolve most rapidly and unpredictably.
B
Which of the following descriptions best represents the gradual model of speciation?
A) Speciation occurs regularly as a result of the accumulation of many small changes. B) An isolated population differentiates quickly from its parent stock as it adapts to its local environment. C) Speciation occurs under unusual circumstances and therefore transitional fossils are hard to find. D) Species undergo little change over long periods interrupted only by short periods of rapid change.
A
One of the finest available sequences of fossils shows how horses have changed slowly and by subtle steps from small shrub-browsing ancestors to the large, grass-grazing modern horse. A large number of fossil species have been named, and it is often difficult to decide on the identity of a fossil horse because transitional forms are common. This record of evolution best fits the idea of
A) the gradual model of speciation. B) punctuated equilibrium. C) adaptive radiation. D) hybrid breakdown.
A
The fossil record shows that for many plant and animal groups, the time between speciation events
A) is usually about 50,000 years. B) varies greatly, but averages 6.5 million years. C) is usually greater than 40 million years. D) is equivalent to the length of one hundred generations of a species.
B
Speciation has occurred when
A) two populations of organisms have been separated for a very long time. B) a change in allele frequency has occurred. C) organisms of one population do not recognize the mating call of another population and so mating does not occur. D) offspring of mating from members of two different populations are able to mate with members of either population.
C
Allopatric speciation is not likely to occur when
A) there is no disruption in gene flow between two populations. B) a geographic barrier forms between two populations. C) several populations become isolated from one another as drying conditions cause a large body of water to become separate smaller bodies of water. D) separated populations adapt to different environmental conditions.
A
Two populations that have been separated by a river are most likely to become separate species if
A) fur color is different in the two populations. B) genes controlling ear development become different so that members of one population have much longer ears than the other. C) genes controlling molecules on the surface of the sperm that bind with egg receptors are different in the two populations.D) feeding habits are different in the two populations.
C
Speciation often occurs when a habitat becomes more heterogeneous. In Lake Victoria different species of cichlids are found in different areas of the lake. The best explanation for this speciation is that
A) natural selection favored different heritable variations in different parts of the lake. B) male cichlids that lived in deep water needed to be seen by females, so they became colorful. C) food was scarce in the lake, so some fish had to learn how to scrape algae, some had to learn to eat insects, and some had to learn to bite leaves. D) humans selected for many different traits in cichlids in order to market them to the aquarium trade.
A
A new plant species may arise in a single generation by
A) errors in meiosis leading to polyploidy. B) a sudden geological disruption causing separation of two populations. C) mutations in genes for flower color. D) changes in the pollinator species.
A
For speciation to occur there mustbe
A) sexual reproduction. B) genetic variation. C) isolation. D) natural selection.
A
In a population of plants with a diploid number of 12, a new individual appeared with a chromosome number of 24. If this organism could self-fertilize, forming offspring with the same number of chromosomes (24), scientists would consider this an example of
A) sympatric speciation. B) behavioral isolation. C) formation of a hybrid zone. D) reduced hybrid fertility.
A
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