Chapter 24: Origin of Species

According to the phylogenetic species concept, what is a species? A. A set of organisms with a unique genetic history B. A population that is physically able to mate even if there are no offspring or the offspring are infertile C. A close of genetically identical organisms D. A population that interbreeds and produces fertile offspring E. A population with a distinct fossil record

A. A set of organisms with a unique genetic history

How are two different species most likely to evolve from one ancestral species? A. Allopatrically, after the ancestral species has split into two populations B. Sympatrically, by a point mutation affecting morphology or behavior C. Allopatrically, due to extensive inbreeding D. Sympatrically, due to extensive inbreeding

A. Allopatrically, after the ancestral species has split into two populations

The original habitat of the North American maggot fly, Rhagoletis pomonella, was native hawthorn trees. About 200 years ago, some populations colonized newly introduced apple trees. The two populations are still classified as subspecies, but sympatric speciation is under way. What has contributed to incipient speciation in the maggot fly? A. Because apples mature more quickly than hawthorn fruit, the apple-feeding flies have been selected for more rapid development B. Maggot flies that feed and lay eggs on apples have gradually become adapted to this fruit C. Apple maggot flies try to avoid mating with hawthorn maggot flies

A. Because apples mature more quickly than hawthorn fruit, the apple-feeding flies have been selected for more rapid development

Which of the various species concepts distinguishes two species based on the degree of genetic exchange between their gene pools? A. Biological B. Genetic C. Ecological D. Morphological

A. Biological

Two animals are considered members of different species if they _____. A. Cannot mate and produce viable, fertile offspring B. Look different C. Are members of different populations D. Are geographically isolated E. Live in different habitats

A. Cannot mate and produce viable, fertile offspring

Which of the following describes the most likely order of events in allopatric speciation? A. Genetic isolation, genetic drift, divergence B. Genetic drift, genetic isolation, divergence C. Genetic isolation, divergence, genetic drift D. Divergence, genetic drift, genetic isolation

A. Genetic isolation, genetic drift, divergence

Two populations of birds with somewhat different coloration live on opposite sides of a peninsula. The habitat between the populations is not suitable for these birds. When birds from the two populations are brought together, they produce young whose appearance is intermediate between the two parents. These offspring will breed with each other or with birds from either parent population, and all offspring of these pairings appear intermediate to various degrees. What keeps the two populations separate? A. Habitat isolation B. Temporal reproductive isolation C. Behavior isolates reproductive activities D. Lack of hybrid viability

A. Habitat isolation

What happens to the hybrid zone when gene flow is established? A. Hybrids cease to be formed B. A population merges with another population C. Weakening of reproductive barriers D. Continued production of hybrids

A. Hybrids cease to be formed

Which statement describes unity within a species? A. Members have the potential to interbreed in nature and produce viable, fertile offspring B. A species is described in terms of its interaction with living and non-living environment C. A species can be distinguished by body shape and other structural features D. The DNA sequence lacks similarities

A. Members have the potential to interbreed in nature and produce viable, fertile offspring

You are confronted with a box of preserved grasshoppers of various species that are new to science and have not been described. Your assignment is to separate them into species. There is no accompanying information as to where or when they were collected. Which species concept will you have to use? A. Morphological B. Ecological C. Biological D. Genetic

A. Morphological

How can reproductive barriers from sympatric populations while their members remain in the same geographic area? A. Polyploidy B. Increased gene flow C. Decreased sexual selection D. Habitat sharing

A. Polyploidy

Among known plant species, which of these have been the two most commonly occurring phenomena leading to the origin of new species? A. Sympatric speciation and polyploidy B. Allopatric speciation and polyploidy C. Allopatric speciation and sexual selection

A. Sympatric speciation and polyploidy

Many songbirds breed in North America in the spring and summer and then migrate to Central and South America in the fall. They spend the winter in these warmer areas, where they feed and prepare for the spring migration north and another breeding season. Two hypothetical species of sparrow, A and B, overwinter together in mixed flocks in Costa Rica. In spring, species A goes to the east coast of North America, and species B goes to the west coast. What can you say about the isolating mechanisms of these two species? A. Their winter habitat has no bearing on their degree of reproductive isolation B. They must have strong prezygotic isolating mechanisms to spend winter in such close proximity C. They must have strong postzygotic isolating mechanisms to spend winter in such close proximity D. Reinforcement must be occuring when they winter together

A. Their winter habitat has no bearing on their degree of reproductive isolation

In hybrid zones where reinforcement is occurring, we should see a decline in _____. A. Gene flow between distinct gene pools B. Mutation rates C. Speciation D. The genetic distinctness of two gene pools

A. gene flow between distinct gene pools

Hybrid zones provide an opportunity to investigate _____. A. The evolution of reproductive isolation B. Polyploidy C. Mutations D. Allopatric speciation E. Punctuated equilibrium

A. the evolution of reproductive isolation - A hybrid zone allows researchers to see what happens when closely related species come together. Reproductive barriers may be strengthened or weakened, depending on environmental and genetic factors.

Plant species A has a diploid number of 12. Plant species B has a diploid number of 16. A new species, C, arises as an allopolyploid from A and B. The diploid number for species C would probably be... A. 56 B. 28 C. 16 D. 14

B. 28

In a species that has two chromosomes, suppose that a male has genotype aa for a gene on chromosome 1 and genotype bb for a gene on chromosome 2. If a female of this species has genotype AA for the gene on chromosome 1 and genotype BB for the gene on chromosome 2, which of the following represents the possible genotypes in a cell of their offspring? A. AA on chromosome 1, bb on chromosome 2 B. Aa on chromosome 1, Bb on chromosome 2 C. AB on chromosome 1, ab on chromosome 2 D. aB on chromosome 1, Ab on chromosome 2

B. Aa on chromosome 1, Bb on chromosome 2

Speciation... A. Occurs only by the accumulation of small genetic changes over vast expanses of time B. Can involve changes to a single gene C. Must begin with the geographic isolation of a small, frontier population D. Occurs at such a slow pace that no one has ever observed the emergence of new species

B. Can involve changes to a single gene

Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. Pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species. These two juniper species are kept separate by _____. A. Behavioral isolation B. Gametic isolation C. Temporal isolation D. Habitat isolation

B. Gametic Isolation

Which of the following is the first step in alloopatric speciation? A. Genetic drift B. Geographic isolation C. Hybridization D. Formation of a reproductive barrier E. Polyploidy

B. Geographic isolation Allopatric speciation occurs when a population of organisms is geographically separated long enough for significant changes to occur. After a period of time, the populations may no longer be able to interbreed

Most causes of speciation are relatively slow, in that they may take many generations to see changes, with the exception of.... A. Natural selection B. Polyploidy C. Reinforcement D. Colonization

B. Polyploidy

The production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) is an example of _____. A. Mechanical isolation B. Reduced hybrid fertility C. Reduced hybrid viability D. Hybrid breakdown

B. Reduced hybrid fertility

How is length of time for speciation estimated? A. Time it takes for speciation to be complete B. Time that elapses when populations of a newly formed species diverge C. Speciation precedes divergence D. Genetic evidence indicated that species originate

B. Time that elapses when populations of a newly formed species diverge

You want to study divergence of populations, and you need to maximize the rate of divergence to see results within the period of your grant funding. You will form a new population by taking some individuals from a source population and isolating them so the two populations cannot interbreed. What combination of characteristics would maximize your chance of seeing divergence in this study? 1. Choose a random sample of individuals to form the new population. 2. Choose individuals from one extreme to form the new population. 3. Choose a species to study that produces many offspring. 4. Choose a species to study that produces a few, large offspring. 5. Place the new population in the same type of environment as the source population. 6. Place the new population in a novel environment compared to that of the source population. A. 1, 4, and 6 B. 2, 3, and 5 C. 2, 3, and 6 D. 1, 3, and 6

C. 2, 3, and 6

The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two populations meet again and ________. A. A decreasing number of viable, fertile hybrids is produced over the course of the next 100 generations B. An increasing number of infertile hybrids is produced over the course of the next 100 generations C. An increasing number is viable, fertile hybrids is produced over the course of the next 100 generations D. No reproduction occurs in the hybrid zone

C. An increasing number is viable, fertile hybrids is produced over the course of the next 100 generations

According to the biological species concept, for speciation to occur, ... A. Large numbers of genes that affect numerous phenotypic traits mush change B. The number of chromosomes in the gene pool must change C. At least one gene, affecting one reproductive barrier, must change D. Changes to centromere location or chromosome size must occur

C. At least one gene, affecting one reproductive barrier, must change

Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian Islands have different elaborate courtship rituals. These rituals involve fighting other males and making stylized movements that attract females. What type of reproductive isolation does this represent? A. Temporal isolation B. Gametic isolation C. Behavioral isolation D. Postzygotic barriers E. Habitat isolation

C. Behavioral isolation

Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile. This kind of isolation is most similar to which of the following reproductive isolating mechanisms? A. Gametic isolation B. Behavioral isolation C. Habitat isolation D. Temporal isolation

C. Habitat isolation

Reinforcement is most likely to occur when _____. A. The environment is changing B. Prezygotic isolating mechanisms are in place C. Hybrids have lower fitness than either parent population D. Gene flow is low

C. Hybrids have lower fitness than either parent population

According to the punctuated equilibria model... A. Natural selection is unimportant as a mechanism of evolution B. Most evolution occurs in sympatric populations C. Most new species accumulate their unique features relatively rapidly as they come into existence, then change little for the rest of their duration as a species D. Speciation is usually due to a single mutation E. Given enough time, most existing species will branch gradually into new species

C. Most new species accumulate their unique features relatively rapidly as they come into existence, then change little for the rest of their duration as a species

The peppered moth provides a well-known example of natural selection. The light-colored form of the moth was predominant in England before the Industrial Revolution. In the mid-19th century, a dark-colored form appeared. The difference is produced by a dominant allele of one gene. By about 1900, approximately 90% of the moths around industrial areas were dark colored, whereas light-colored moths were still abundant elsewhere. Apparently, birds could readily find the light moths against the soot-darkened background in industrial areas and, therefore, were eating more light moths. Recently, use of cleaner fuels has greatly reduced soot in the landscape, and the dark-colored moths have been disappearing. Should the two forms of moths be considered separate species? A. Yes; they have completely different coloration B. Yes; natural selection has affected the frequency of the two different forms C. No; they still can interbreed D. Yes; they are reproductively isolated based on habitat

C. No; they still can interbreed

Two species of tree frogs that live sympatrically in the northeastern United States differ in ploidy: Hyla chrysoscelis is diploid, and Hyla versicolor is tetraploid. The frogs are identical in appearance, but their mating calls, which females use to find mates, differ. Which difference most likely evolved first? A. Habitat differentiation B. Difference in mating calls C. Polyploidy D. Polyploidy and different mating calls must have evolved at the same time

C. Polyploidy

The common edible frog of Europe is a hybrid between two species, Rana lessonae and Rana ridibunda. The hybrids were first described in 1758 and have a wide distribution, from France across central Europe to Russia. Both male and female hybrids exist, but when they mate among themselves, they are rarely successful in producing offspring. What can you infer from this information? A. These two species are likely in the process of fusing back into one species B. Prezygotic isolation exists between the two frog species C. Postozygotic isolation exists between the two frog species D. The hybrids form a separate species under the biological species concept

C. Postzygotic isolation exists between the two frog species

The difference between geographic isolation and habitat differentiation (isolation) is the..... A. Amount of genetic variation that occurs among two gene pools as speciation occurs B. Identity of the kingdom or domain in which these phenomena occur C. Relative location of two populations as speciation occurs D. Speed (tempo) at which two populations undergo speciation

C. Relative location of two populations as speciation occurs

The largest unit within which gene flow can readily occur is a... A. Phylum B. Genus C. Species D. Hybrid E. Population

C. Species

Two researchers experimentally formed tetraploid frogs by fertilizing diploid eggs from Rana porosa brevipoda with diploid sperm from Rana nigromaculata. When they mated these tetraploid frogs with each other, most of the offspring that survived to maturity were tetraploid, with chromosome sets of both diploid parent species. Based on these results, if this type of tetraploid formed in the wild, what would be the result? A. The two parent species would interbreed and fuse into one species B. The tetraploids would be selected against C. The tetraploids would be reproductively isolated from both parent species D. The two parent species would recognize each other as mates

C. The tetraploids would be reproductively isolated from both parent species

How long does it take new species to form on Earth? A. Speciation no longer takes place on Earth B. Millions of years C. The time required varies considerably

C. The time required varies considerably

A certain species of salamander was split into two populations by a wide, dry valley, and the populations began to diverge from each other. After a period of time, some members of the two populations began to interbreed in a hybrid zone at the southern end of the valley. Only weak reproductive barriers existed by this time, so the two populations could freely interbreed and re-establish gene flow. This outcome in a hybrid zone is known as _____. A. Punctuated equilibrium B. Reinforcement C. Fusion D. Speciation E. Stability

C. fusion Fusion refers to the weakening of reproductive barriers, allowing the two populations to fuse and remain (or become) one species.

Rank the following in order from most general to most specific: 1. Gametic isolation 2. Reproductive isolating mechanism 3. Sperm-egg incompatibility in sea urchins 4. Prezygotic isolating mechanism A. 2, 3, 1, 4 B. 4, 2, 1, 3 C. 4, 1, 2, 3 D. 2, 4, 1, 3

D. 2, 4, 1, 3

Which of the following has been shown to cause speciation most rapidly? A. Sexual selection B. Hybridization C. Differential resource exploitation D. Autopolyploidy E. Punctuated equilibrium

D. Autopolyploidy Autopolyploidy has been shown to produce nearly instantaneous speciation in plants

There is still some controversy among biologists about whether Neanderthals should be placed within the same species as modern humans or into a separate species of their own. Most DNA sequence data analyzed so far indicate that there was probably little or no gene flow between Neanderthals and Homo sapiens. Which species concept describing species relationship between modern humans and Neanderthals is most applicable in these observations? A. Ecological B. Genetic C. Morphological D. Biological

D. Biological

About 3 million years ago, the Isthmus of Panama (a narrow strip of land connecting North and South America) formed, dividing marine organisms into Pacific and Caribbean populations. Researchers have examined species of snapping shrimp on both sides of the isthmus. Based on the morphological species concept, there appeared to be seven pairs of species, with one species of each pair in the Pacific and the other in the Caribbean. The different species pairs live at somewhat different depths in the ocean. Using mitochondrial DNA sequences, the researchers estimated phylogenies and found that each of these species pairs, separated by the isthmus, were indeed each other's closest relatives. The researchers investigated mating in the lab and found that many species pairs were not very interested in courting with each other, and any that did mate almost never produced fertile offspring. If the isthmus formed gradually rather than suddenly, what pattern of genetic divergence would you expect to find in these species pairs? A. Smaller percentage of difference DNA sequence between species that inhabit than between shallow water B. Similar percentages of difference in DNA sequence between all pairs of sister species C. Greater percentage of difference in DNA sequence between species that inhabit shallow water than between species that inhabit deep water D. Greater percentage of difference in DNA sequence between species that inhabit deep water than between species that inhabit shallow water

D. Greater percentage of difference in DNA sequence between species that inhabit deep water than between species that inhabit shallow water

If biological species are defined in terms of reproductive compatibility, the formation of a new species hinges on ________. A. Gene flow B. Gene pool expansion C. Hybrid formation D. Reproductive isolation

D. Reproductive isolation

In a hypothetical situation, a certain species of flea feeds only on pronghorn antelopes. In the western United States, pronghorns and cattle often associate with one another in the same open rangeland. Some of these fleas develop a strong preference for cattle blood and mate only with other fleas that prefer cattle blood. The host mammal can be considered as the fleas' habitat. If this situation persists, and new species evolve, this would be an example of _____. A. Sympatric speciation and temporal isolation B. Allopatric speciation and habitat isolation C. Allopatric speciation and gametic isolation D. Sympatric speciation and habitat isolation

D. Sympatric speciation and habitat isolation

A small number of birds arrive on an island from a neighboring larger island. This small population begins to adapt to the new food plants available on the island, and their beaks begin to change. About twice a year, one or two more birds from the neighboring island arrive. These new arrivals ________. A. Speed up the process of speciation B. Tend to promote adaptation to the new food plants C. Represent a colonizing event response D. Tend to slow adaption to the new food plants

D. Tend to slow adaption to the new food plants

Sympatric speciation is... A. The process by which most animal species have evolved B. The emergency of many species from a single ancestor C. Initiated by the appearance of a geographic barrier D. The appearance of a new species in the same area as the parent population E. Especially important in the evolution of island species

D. The appearance of a new species in the same area as the parent population It is due to a radical change in the genome

Suppose that a group of male pied flycatchers migrated from a region where there were no collared flycatchers to a region where both species were present. Assuming events like this are very rare, which of the following scenarios is LEAST likely? A. Migrant males would mate with collared females more often than with pied females B. Migrant pied males would produce fewer offspring than would resident pied males C. Pied females would rarely mate with collared males D. The frequency of hybrid offspring would decrease

D. The frequency of hybrid offspring would decrease