CH 24 Mastering biology

(Allopatric speciation) Why are the large finches now living on the Galápagos Islands different from the original source population from a nearby island?

1. The separation of habitats reduced gene flow between the populations. 2. Genetic drift occurred in the two populations. 3. Natural selection favored individuals that were more fit in the new environment.

(q 57) Which of the following statements correctly describes a change that must occur for a new species to arise?

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

(misconception 119) 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?

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

How can an allopolyploid plant become a biologically fit new species?

Nondisjunction event during mitosis

(misconception 118) Adaptive radiations on archipelagos (island chains) represent some of the best-understood speciation events. Why is an ancestral species more likely to give rise to multiple descendent species on an archipelago than on an equal-sized area of mainland?

Populations on nearby islands are more likely to be genetically isolated than populations that are equally close to one another on the mainland.

(Q 48) The number of cichlid species in Lake Victoria is declining, in part because of predation by Nile perch. Which of the following factors is also likely to contribute to the decline in the number of cichlid species in Lake Victoria?

fusion of species

(pre test Q 5) Which of the following is the first step in allopatric speciation?

geographic isolation

(pre test Q 4) Which of these is an example of temporal isolation between two species?

one species is nocturnal, and the other species is not

(Q. 1) The largest unit within which gene flow can readily occur is a

species

Plant species F has a diploid number of 8. Plant species G has a diploid number of 10. What would be the diploid number of an allopolyploid hybrid of species F and species G?

18

(Q. 41) Plant species X has a diploid number of 12. Plant species Y has a diploid number of 16. A new species, Z, arises as an allopolyploid from X and Y. The diploid number for species Z would probably be ________.

28

(Q. 6) Plant species A has a diploid chromosome 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

28

(Allopatric speciation) What is genetic drift?

A change in allele frequencies caused by random events

(get ready Q 2) 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?

Aa on chromosome 1, Bb on chromosome 2

_____ is rapid speciation under conditions in which there is little competition.

Adaptive radiation

(Q. 5) Which of the following factors would be the most likely to contribute to allopatric speciation?

Different mutations begin to distinguish the gene pools of the separated populations.

(misconception 120) In Europe, there is a long narrow hybrid zone, shown in red on the map, between the high-altitude habitat of the yellow-bellied toad and the lowland habitat of the fire-bellied toad. Despite this, there is little gene flow between the two species. Select the correct explanation.

Hybrids have poor survival and reproduction and thus produce few viable offspring with members of either parent species.

(Allopatric speciation) A population of birds colonizes an area in which the insects upon which they feed live inside trees. Which of the following events accounts for an observed increase in average beak size in the bird population over time?

Increased fitness of large-beaked birds, leading to natural selection

The sequence of events illustrated in this figure results in a fertile hybrid plant called an allopolyploid. Which of the following statements is the most complete description of an allopolyploid?

It contains more than two sets of chromosomes, which are derived from two species.

What role does nondisjunction play in the formation of a fertile allopolyploid hybrid?

It doubles the chromosome number in the hybrid.

(Q. 9) Which of the following statements best describes macroevolution?

Macroevolution is evolution above the species level.

(get ready Q 1) Which of the following statements about meiosis is correct?

Meiosis produces cells that differ genetically from the parent cell.

(Q. 7) Which of the following statements best describes unity within a species?

Members of a given species have the potential to interbreed in nature and produce viable, fertile offspring.

(Allopatric speciation) A subset of a population of birds leaves its habitat on the mainland and colonizes a nearby island. The birds, after a period of time, become reproductively isolated. The island sinks and the population of birds that lived on the island returns to its original habitat. Which of the following statements about these bird populations is true?

The populations will not be able to interbreed because they are different species.

(Q 37) In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp, 15 species on the Pacific side and 15 different species on the Atlantic side. Species live at different water depths. Morphological and genetic data show that Atlantic and Pacific species that live at similar depths are sister species. Geological evidence indicates that the Isthmus of Panama started rising about 10 million years ago and the oceans were completely separated by the isthmus about 3 million years ago. Which of the following statements would best explain why the shallow-water sister species are more similar to each other than are the deeper-water species?

The shallow-water sister species have been geographically isolated from each other for a shorter time than the deep-water sister species have been.

(Q. 28) Two researchers experimentally formed tetraploid frogs by fertilizing diploid eggs from Rana porosa brevipoda with diploid sperm from Rana nigromaculata. When they allowed the tetraploid frogs to mate 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 most likely result?

The tetraploids would be reproductively isolated from both parent species.

(Q. 4) Bird guides once listed the myrtle warbler and Audubon's warbler as distinct species. Recently, these birds have been classified as eastern and western forms of a single species, the yellow-rumped warbler. Which of the following pieces of evidence, if true, would be cause for this reclassification?

The two forms interbreed often in nature, and their offspring survive and reproduce well.

(Q. 6) Almost all peppered moths in England were light colored before the Industrial Revolution. However, some dark forms were collected-the dark color is determined by a single, dominant allele of one gene. The bark of trees became darker during the Industrial Revolution in areas where heavy coal use in factories caused pollution. By about 1900, approximately 90% of the moths around industrial areas were dark, whereas light-colored moths were still abundant elsewhere. Apparently, birds could readily find the light moths against the dark trees in industrial areas and, therefore, were eating more light moths. Recently, use of cleaner fuels has resulted in tree bark becoming lighter again and the dark-colored moths have been disappearing. Which of the following statements best explains whether we should consider the forms different species?

They are NOT different species-as shown by the fact that they can interbreed.

(Q. 8) The common edible frog of Europe is a hybrid between two named 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 rarely produce offspring. Which of the following statements is the best inference about the two Rana species?

They are different species and postzygotic isolation exists between the two frog species.

(Q 42) 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. Which of the following effects is most likely to result from the immigration?

a decrease in birds' adaptation to the new food plants

(Q. 4) Three populations of crickets look very similar, but the males have different courtship songs. If the cricket populations were to contact each other in the wild, the different courtship songs would most likely function as which type of reproductive isolating mechanism?

behavioral

(Q. 2) 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?

behavioral isolation

(Q. 10) Which of the various species concepts distinguishes two species based on the degree of genetic exchange between their gene pools?

biological

(Q. 23) A team of scientists plans to study divergence of populations and needs to maximize the rate of divergence to see results within the period of their grant funding. They will form a new population by taking some individuals from a source population and isolating them so the source and new populations cannot interbreed. Which of the following strategies would maximize the likelihood of seeing divergence between the source and new populations in this study?

choosing individuals from one extreme of the source population to form the new population and placing the new population in a novel environment

(Allopatric speciation) True or false? The last ice age produced many different species mainly because populations dispersed and colonized new habitats.

false

True or false? A mating between a tetraploid individual and a diploid individual produces biologically fit offspring.

false

(pre test q 8) 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 __________.

fusion

(Q. 18) Two juniper trees (Juniperus scopulorum and J. monosperma) have overlapping geographic 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. Which of the following isolating mechanisms keeps the two species separate?

gametic isolation

(Q. 19) Which of the following factors is the primary criterion for determining species boundaries when applying the biological species concept?

gene flow

What prevents speciation from occurring in sympatric populations?

gene flow

(get ready Q 3) A windstorm transports a few seeds of a plant species from Island A, where the species is abundant, to Island B, where prior to this event the plant species was not found. The environmental conditions on the two islands are very similar, but the islands are located far away from one another. Over time, a small population of this plant becomes established on Island B. A biologist samples plants on both islands and finds that allele frequencies on Island A differ substantially from allele frequencies on Island B at several genetic loci not known to affect survival or reproduction. Based on this information, the observed genetic changes mostly likely resulted from?

genetic drift

(Q 35) Two species of fruit flies occur on the volcanic, equatorial West African island of Sao Tome that rose from the Atlantic Ocean 14 million years ago. Drosophila santomea occurs only on at higher elevations, while D. yakuba inhabits the lowlands. D. yakuba also occurs on the African mainland. On Sao Tome a hybrid zone between the two species exists at middle elevations. Hybrid males, but not females, are sterile, and hybrids are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Using this information, which of the following phenomena is the best initial hypothesis for how D. santomea descended from D. yakuba?

habitat differentiation

(Q. 1) 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 in captivity, they interbreed and produce fertile young whose appearance is intermediate between the two parents. In the wild, the two populations remain separate as a result of which of the following factors?

habitat isolation

(Q. 13) 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?

habitat isolation

How many chromosomes would be found in an allopolyploid plant if its parents had diploid numbers of 2 and 10, respectively?

haploid number of 6

(Q. 17) Which of the following characteristics is a postzygotic barrier that prevents hybrids between two species from producing offspring?

hybrid breakdown

(Q 44) Which of the following conditions is most likely to reinforce isolating mechanisms between two species that occasionally hybridize?

hybrids have lower fitness than either parent population

Gametes from two plant species combine and produce a haploid zygote, and that zygote develops into a haploid, hybrid plant. Why is the hybrid plant sterile?

meiosis cannot occur and the cells do not contain homologous chromosomes

(Q. 12) Recently, a museum scientist discovered a case of preserved grasshoppers that do not resemble any named species. No information about when and where the specimens were collected is available. Which of the following species concepts would be most appropriate to use in identifying and naming the new specimens?

morphological

(Q. 3) According to the punctuated equilibria model,

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.

(Q. 27) Which of the following possible causes of speciation is most likely to cause rapid speciation?

polyploidy

(Q. 29) Which of the following factors is most likely to produce a reproductive barrier in a single population?

polyploidy

(Q. 30) Two species of tree frogs that live sympatrically in the eastern 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?

polyploidy

(pre test q 9) According to the __________ model, morphological change occurs in spurts; species evolve relatively rapidly then remain unchanged for long periods.

punctuated equilibrium

(Q. 16) Which of the following characteristics are demonstrated by the production of sterile mules after female horses mate with male donkeys?

reduced hybrid fertility

(Q. 15) Two species of frogs belonging to the same genus occasionally mate, but the embryos stop developing after a day and then die. Which of the following mechanisms keep the species separate?

reduced hybrid viability

(Allopatric speciation) Which of the following statements about reinforcement is true?

reinforcement is a type of natural selection

(Q. 32) Which of the following statements best describes the difference between geographic isolation and habitat differentiation (isolation)?

relative location of two populations as speciation occurs

(Q. 2) If biological species are defined in terms of reproductive compatibility, which of the following factors determines the formation of a new species?

reproductive isolation

(Q 36) On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish prefer to breed only with males that have their same swimming ability. Which of the following phenomena have helped promote divergence between the mosquito populations?

sexual selection and natural selection

(Q 47) Which of the following outcomes is most likely in hybrid zones where reinforcement of isolating mechanisms is occurring?

speciation

(Q 54) According to the concept of punctuated equilibrium, the "sudden" appearance of a new species in the fossil record means that ________.

speciation occurred rapidly in geologic time

(Q. 31) In the western United States, pronghorn antelopes and domestic cattle often associate with one another in the same open rangeland. In a hypothetical situation, a certain species of flea originally fed only on pronghorn antelopes. Some of these fleas developed a strong preference for cattle blood and mated only with other fleas that also preferred cattle blood. The host mammal can be considered as the fleas' habitat. Which of the following processes most likely occurred if the situation persisted and a new species evolved?

sympatric speciation and habitat isolation

(misconception 117) Select the correct statement describing sympatric speciation.

sympatric speciation can occur in a single generation

(Q 34) Beetle pollinators of a particular plant are attracted to its flowers' bright orange color. The beetles not only pollinate the flowers, but they mate while inside the flowers. A mutant version of the plant with red flowers becomes more common with the passage of time. A particular variant of the beetle prefers the red flowers to the orange flowers. Over time, these two beetle variants diverge from each other to such an extent that interbreeding is no longer possible. Which of the following possible causes of speciation best describes the beetle example and what factor has driven it?

sympatric speciation; habitat differentiation

Which term is used to describe populations that live close enough to interbreed?

sympatry

What would be the ploidy of the viable gametes produced by a tetraploid individual if nondisjunction of all chromosomes occurred in meiosis I?

tetraploid

(pre test Q 6) Sympatric speciation is __________.

the appearance of a new species in the same area as the parent population

(pre test q 7) Hybrid zones provide an opportunity to investigate __________.

the evolution of reproductive isolation

(misconception 116) How long does it take new species to form on Earth?

the time required varies considerably

(Q. 5) 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, species X and species Y, overwinter together in mixed flocks in Costa Rica. In spring, species X goes to the east coast of North America, and species Y goes to the west coast. Which of the following factors most likely keeps these species separate?

the two species reproduce in different geographic areas

Which of the following statements about autopolyploid individuals is true?

they contain more than two haploid sets of chromosomes

(Allopatric speciation) True or false? A flood that separates a population of frogs onto opposite sides of a lake is an example of a vicariance event that may result in allopatric speciation.

true

(Q. 3) Which of the following provides an example of a mechanical isolation as a prezygotic barrier?

two snails have shells that spiral in different directions

(Q 46) Which of the following statements is the best definition of a hybrid zone?

an area where mating occurs between members of two closely related species, producing viable offspring

(Q 45) One possible outcome of hybridization is fusion of two species. Which of the following conditions is most likely to increase the probability of fusion of the two species as a result of hybridization?

an increasing number of viable, fertile hybrids is produced over the course of the next 100 generations

(pre test q 10) Which of the following has been shown to cause speciation most rapidly?

autopolyploidy

(Q 56) Which of the following statements most accurately applies to speciation?

Speciation can involve changes to a single gene.

(Q 53) A female fly, full of fertilized eggs, is swept by high winds to an island far from the mainland. She is the first, and only, fly to arrive on this island. Thousands of years later, her numerous offspring occupy the island, but none of them resembles her. There are, instead, several species and their geographic ranges overlap. Each species eats a different kind of food. None of the species can fly and the balancing organs of males differ among species and are now used in courtship displays. Fly species W produces fertile offspring with species Y, but not with species X or Z. Furthermore, X and Z do not hybridize. Which of the following statements about species W and Y is most likely to be accurate?

Species W and Y may fuse into a single species if their hybrids remain fertile over the course of many generations.

(Q. 25) Which of the following methods is most likely to lead to the production of two species from one ancestral species?

allopatrically, after the ancestral species has split into two populations

Mass extinctions create conditions that promote _____.

adaptive radiation

The appearance of an evolutionary novelty promotes _____.

adaptive radiation

The different finch species found on the Galápagos Islands probably arose as a result of _____.

adaptive radiation

(Q. 26) House finches (birds) occurred only in western North America until 1939, when a few individuals were released in New York City. These individuals established a breeding population and gradually expanded their range. The western population also expanded its range somewhat eastward, and the two populations have recently come in contact. Which of the following terms best describes the process that had occurred if the two forms did not interbreed when their expanding ranges met?

allopatric speciation

Feathers either play a role, or may have played a role, in _____.

courtship, gliding, extended hops, flight