Deck 24: Species and Speciation

Question 1

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?

A) reduced hybrid viability
B) hybrid breakdown
C) reduced hybrid fertility
D) gametic isolation

Answer 1

A

Question 2

Which of the following statements best describes a limitation of the biological species concept?

A) The biological species concept cannot be applied to fossils because the biological species concept uses reproductive isolation to define species.
B) The biological species concept cannot be applied to haploid species because the biological species concept delineates species by the presence of gene flow between species.
C) The biological species concept cannot be applied to polyploid species because the biological species concept separates species by the absence of gene flow between them.
D) The biological species concept cannot be applied to sexual species because the biological species concept separates species by the absence of gene flow between species.

Answer 2

A

Question 3

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?

A) temporal reproductive isolation
B) lack of hybrid viability
C) behavior isolates reproductive activities
D) habitat isolation

Answer 3

D

Question 4

Which of the following factors is the primary criterion for determining species boundaries when applying the biological species concept?

A) geographic isolation
B) niche differences
C) gene flow
D) morphological similarity

Question 5

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) temporal isolation
B) behavioral isolation
C) habitat isolation
D) gametic isolation

Question 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?

A) They are different species-as shown by the fact that natural selection has affected the frequency of the two forms.
B) They are different species-as shown by the fact that the two forms are reproductively isolated by habitat.
C) They are NOT different species-as shown by the fact that they live in the same habitats.
D) They are NOT different species-as shown by the fact that they can interbreed.

Question 7

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?

A) temporal
B) postzygotic
C) behavioral
D) gametic

Question 8

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

A) gene flow
B) reproductive isolation
C) hybrid formation
D) gene pool expansion

Question 9

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?

A) They are different species and postzygotic isolation exists between the two frog species.
B) Prezygotic isolation exists between the two frog species.
C) The two species are likely in the process of fusing back into one species.
D) The hybrids form a separate species under the biological species concept.

Question 10

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?

A) habitat isolation
B) temporal isolation
C) gametic isolation
D) behavioral isolation

Question 11

Which of the following statements best describes unity within a species?

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

Question 12

Which of the following characteristics are demonstrated by the production of sterile mules after female horses mate with male donkeys?

A) reduced hybrid viability
B) hybrid breakdown
C) reduced hybrid fertility
D) mechanical isolation

Question 13

The diagram represents the splitting of one population into two separate lineages that become more different over time (the distance between the two lines represents the amount of difference between the two lineages). Which of the following statements about the two lineages is most accurate?

A) They are more likely to be separate species at time Z than at time X.
B) They are likely to be more different at time X than at time Z.
C) They are more likely to fuse if they start interbreeding at time Z than at time X.
D) There are likely to be more isolating mechanisms at time X than at time Z.

Question 14

Which of the following provides an example of a mechanical isolation as a prezygotic barrier?

A) two species live in different habitats
B) two species mate at different times
C) two species share courtship activities
D) two snails have shells that spiral in different directions

Question 15

Which of the various species concepts distinguishes two species based on the degree of genetic exchange between their gene pools?

A) genetic
B) ecological
C) biological
D) morphological

Question 16

Lions and tigers sometimes breed in zoos, but hybrids have not been seen in nature and even in zoos they do not reproduce well. Which of the following statements is the best conclusion that can be derived from this information?

A) The biological species concept is invalid because hybrids can be formed.
B) Lions and tigers are not actually different species because they can produce viable offspring in captivity.
C) The morphological or ecological species concepts must be used rather than the biological species concept because there could be gene flow between the species in nature.
D) The biological species concept can be applied because species are, in part, defined by the inability to produce viable, fertile offspring with other species.

Question 17

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?

A) biological
B) genetic
C) ecological
D) morphological

Question 18

Which of the following characteristics is a postzygotic barrier that prevents hybrids between two species from producing offspring?

A) increased hybrid vulnerability
B) increased hybrid fertility
C) hybrid breakdown
D) hybrid gamete isolation

Question 19

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?

A) strong postzygotic isolating mechanisms in the winter
B) strong prezygotic isolating mechanisms in the winter
C) the two species reproduce in different geographic areas
D) reinforcement of isolating mechanisms must be occurring in the spring

Question 20

Which of the following statements best describes macroevolution?

A) Macroevolution is the same as microevolution, but includes the origin of new species.
B) Macroevolution is evolution above the species level.
C) Macroevolution is defined as the evolution of microscopic organisms into organisms that can be seen with the naked eye.
D) Macroevolution is defined as a change in allele or gene frequency over the course of many generations.

Question 21

Which of the following organisms would be LEAST able to cross a geographic barrier of water that could lead to allopatric speciation?

A) birds
B) plants with wind-dispersed pollen
C) small rodents
D) mountain lions

Question 22

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?

A) sympatric speciation and habitat isolation
B) sympatric speciation and temporal isolation
C) allopatric speciation and habitat isolation
D) allopatric speciation and gametic isolation

Question 23

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?

A) increased gene flow and sexual selection
B) bottlenect effect and sexual selection
C) bottlenect effect and founder effect
D) sexual selection and natural selection

Question 24

Which of the following factors is most likely to produce a reproductive barrier in a single population?

A) increased gene flow
B) polyploidy
C) decreased sexual selection
D) habitat sharing

Question 25

Which of the following possible causes of speciation is most likely to cause rapid speciation?

A) polyploidy
B) reinforcement
C) colonization
D) natural selection

Question 26

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. If the geological evidence has been misinterpreted and the isthmus had formed very rapidly (in less than 1,000 years), which of the following predictions is most likely?

A) similar percentages of difference in DNA sequences between all pairs of sister species
B) greater percentage of difference in DNA sequences between sister species that inhabit deep water than between sister species that inhabit shallow water
C) greater percentage of difference in DNA sequences between sister species that inhabit shallow water than between sister species that inhabit deep water
D) greater percentage of difference in DNA sequences between Atlantic species than between Pacific species

Question 27

Which of the following methods is most likely to lead to the production of two species from one ancestral species?

A) sympatrically, by a point mutation affecting morphology or behavior
B) sympatrically, due to extensive inbreeding
C) allopatrically, due to extensive inbreeding
D) allopatrically, after the ancestral species has split into two populations

Question 28

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?

A) polyploidy
B) difference in breeding seasons
C) habitat differentiation
D) female preference for male mating calls

Question 29

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

A) relative location of two populations as speciation occurs
B) speed (tempo) at which two populations undergo speciation
C) amount of genetic variation that occurs among two gene pools as speciation occurs
D) identity of the kingdom or domain in which these phenomena occur

Question 30

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?

A) The shallow-water sister species have been geographically isolated from each other for a shorter time than the deep-water sister species have been.
B) Cold temperatures, associated with deep water, have accelerated the mutation rate, resulting in faster divergence in deep-water shrimp.
C) The rise of the land bridge was accompanied by much volcanic activity. Volcanic ash contains heavy metals, which are known mutagens. Ash fall caused high levels of heavy metals in the ocean sediments underlying the deep water, resulting in accelerated mutation rates and faster divergence in deepwater shrimp.
D) Fresh water entering the ocean from the canal is both less dense and cloudier than seawater. The cloudy fresh water interferes with the ability of shallow-water shrimp to locate mating partners, which reduces the frequency of mating, thereby slowing the introduction of genetic variation.

Question 31

The diagram represents the splitting of one population into two separate lineages that become more different over time (the distance between the two lines represents the amount of difference between the two lineages). Which of the following scenarios is most likely result in the patterns shown in the diagram?

A) a glacier that retreats northward and allows contact between eastern and western populations
B) an earthquake that pushes debris into the middle of a lake and makes two unconnected lakes
C) erosion of a mountain that separated two closely related populations
D) building of a canal by people to connect two rivers

Question 32

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?

A) prezygotic isolation
B) reinforcement
C) allopatric speciation
D) sympatric speciation

Question 33

New species can sometimes arise via hybridization and subsequent polyploidy. Which of the following describes the likely geographic and reproductive relationships between the hybridizing species?

A) The two species are allopatric and breed at different times of the year.
B) The two species are sympatric and breed during the same seasons of the year.
C) The two species are sympatric, but breed during different times of the year.
D) The two species can be either allopatric or sympatric, but breed during the same seasons of the year.

Question 34

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. The sister species on each side of the isthmus cannot interbreed because the water in the canal is fresh water, not salt water, and provides a barrier to reproduction. A sea-level, salt-water canal between the two oceans has been proposed to make transport across the isthmus easier. Which of the following outcomes is the most likely result if such a canal were built?

A) The sister species will continue to diverge from each other.
B) None of the sister species will interbreed with each other.
C) The Atlantic and Pacific shrimp will continue to live in their respective oceans and not enter the new canal.
D) Shallow-water species from the two oceans that are sister species would be more likely to interbreed with each other than would be deep-water species.

Question 35

The following question is based on information from Kondo Y. and Kashiwagi A., Experimentally induced autotetraploidy and allotetraploidy in two Japanese pond frogs, Journal of Herpetology 38(3):381−92 (2004).
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?

A) The two parent species would interbreed and fuse into one species.
B) The two parent species would recognize each other as mates.
C) The tetraploids would be reproductively isolated from both parent species.
D) The tetraploids would invade the habitats of both parental species and cause them to go extinct.

Question 36

Two species of fruit flies occur on the volcanic, equatorial West African island of Sao Tomé 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 Tomé 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?

A) allopolyploidy
B) autopolyploidy
C) habitat differentiation
D) sexual selection

Question 37

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?

A) allopatric speciation; ecological isolation
B) allopatric speciation; behavioral isolation
C) sympatric speciation; habitat differentiation
D) sympatric speciation; allopolyploidy

Question 38

Which of the following factors most likely accounts for the fact that polyploids are much more common in plants than in animals?

A) A tetraploid plant is more likely to be able to self-fertilize and produce offspring, but a tetraploid animal would need a second, independently produced tetraploid with which to mate.
B) A diploid plant is more likely to be able to self-fertilize and produce offspring, but a diploid animal almost always needs another diploid as a mate.
C) Plants are more likely to produce diploid gametes than are animals.
D) Meiotic mechanisms are less reliable in plants than in animals.

Question 39

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. If the isthmus indeed formed gradually, which of the following patterns of genetic differences is most likely in these species pairs?

A) similar percentages of difference in DNA sequences between all pairs of sister species
B) greater percentage of difference in DNA sequences between sister species that inhabit deep water than between sister species that inhabit shallow water
C) greater percentage of difference in DNA sequences between sister species that inhabit shallow water than between sister species that inhabit deep water
D) greater percentage of difference in DNA sequences among Atlantic species than among Pacific species

Question 40

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?

A) choosing individuals with the most common phenotype in the source population to form the new population and placing the new population in the same type of an environment as the source population
B) choosing individuals with the most common phenotype in the source population to form the new population and placing the new population in a novel environment as compared to that of the source population
C) choosing individuals from one extreme of the source population to form the new population and placing the new population in the same type of an environment as the source population
D) choosing individuals from one extreme of the source population to form the new population and placing the new population in a novel environment

Question 41

Which of the following statements about stable hybrid zones is most accurate?

A) Stable hybrid zones rarely persist for more than 10-20 years.
B) Stable hybrid zones are most likely to be narrow because intermediate environmental conditions where hybrids are less fit than the parental species are likely to be narrow.
C) Stable hybrid zones are likely if strong pre-mating isolating mechanisms between the two species exist.
D) Stable hybrid zones are likely even if hybrids are selected against, if the hybrid zone is narrow and the parental species come in contact frequently.

Question 42

Which of the following statements most accurately applies to speciation?

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

Question 43

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?

A) Species W and Y have genomes that are too dissimilar for successful meiosis to occur in hybrid flies.
B) Species W and X have more genetic similarity with each other than either does with the other two species.
C) Species W and Y may fuse into a single species if their hybrids remain fertile over the course of many generations.
D) Species W and Y will both be selected to avoid mating with each other.

Question 44

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) an increase in the speed of speciation
B) an increase in birds' adaptation to the new food plants
C) a decrease in birds' adaptation to the new food plants
D) another round of incipient speciation

Question 45

A team of scientists is trying to understand the evolutionary history of three species of grasses. They hypothesize that Species T is a descendent of a hybrid between Species R and Species S. Which of the following experimental approaches would best help elucidate the evolutionary history of these three species?

A) Hybridize Species R and S; plant the hybrid offspring in environmental conditions similar to those of Species R; follow the morphological and genetic changes in the offspring of the hybrids; and compare any observed changes to Species R.
B) Hybridize Species R and S; plant the hybrid offspring in environmental conditions resembling those of Species R, S, and T; follow morphological and genetic changes in the offspring of the hybrids; and compare the observed changes to Species T.
C) Sequence the DNA of all three species and determine which alleles are unique to each species.
D) Hybridize Species R and S; induce tetraploidy in the hybrids; and compare the hybrids to Species T.

Question 46

Which of the following statements about the punctuated and gradual models of speciation is most accurate?

A) Although speciation can occur rapidly or gradually, the fossil record is not always detailed enough to determine how rapidly a particular speciation event proceeded.
B) The fossil record can only determine if the punctuated model is relevant or not to a particular speciation event.
C) Genetic differences can only determine if the gradual model is relevant or not to a particular speciation event.
D) The fossil record can be used to determine which speciation model best explains a particular speciation event.

Question 47

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

A) the environment is changing
B) hybrids have lower fitness than either parent population
C) prezygotic isolating mechanisms are in place
D) gene flow is low

Question 48

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

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

Question 49

Lions and tigers sometimes breed in zoos, but hybrids have not been seen in nature, nor can the hybrids in zoos reproduce well. Which of the following statements is the best conclusion that can be derived from this information?

A) The two species will eventually fuse.
B) They are not actually different species.
C) Scientists should look more closely for hybrid zones between the species.
D) Breeding in zoos is most likely the effect of isolation from available, appropriate mates.

Question 50

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

A) the species is now extinct
B) speciation occurred in one generation
C) speciation occurred rapidly in geologic time
D) the species will consequently have a relatively short existence compared with other species

Question 51

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?

A) no reproduction occurs in the hybrid zone
B) an increasing number of infertile hybrids is produced over the course of the next 100 generations
C) an increasing number of viable, fertile hybrids is produced over the course of the next 100 generations
D) a decreasing number of viable, fertile hybrids is produced over the course of the next 100 generations

Question 52

Which of the following processes would contribute to divergence between lineages once divergence has already begun?

A) sexual selection and habitat differences
B) sexual selection and polyploidy
C) polyploidy and hybridization
D) habitat differences and hybridization

Question 53

Some geographic areas contain two closely related species of birds (sympatry), while other areas contain only one of the species (allopatry). Males from allopatric populations look very similar to each other, but males in the sympatric populations look different from each other and from both allopatric types of males. Which of the following outcomes is most likely if a female in a sympatric area is courted by a male that migrated into the area from an allopatric area?

A) The female is more likely to mate with the immigrant than with a male native to the area.
B) The female is less likely to mate with the immigrant than with a male native to the area.
C) The female is equally likely to mate with the immigrant or with a male native to the area.
D) The female is likely to mate with both males.

Question 54

Which of the following statements is the best definition of a hybrid zone?

A) an area where the ranges of two closely related species overlap but do not interbreed
B) an area where mating occurs between members of two closely related species, producing viable offspring
C) an area where sterile hybrids form, kept separate by postzygotic barriers
D) an area where members of two closely related species intermingle, but gene flow is prevented by prezygotic barriers

Question 55

The largest unit within which gene flow can readily occur is a ________.

A) population
B) species
C) genus
D) hybrid

Question 56

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 ________.

A) 14
B) 16
C) 28
D) 56

Question 57

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

A) increased gene flow between distinct gene pools
B) speciation
C) a decrease in the genetic distinctness of two gene pools
D) formation of a stable hybrid zone

Question 58

Which of the following possible isolating mechanisms prevents individuals from wasting time and energy hybridizing with an individual of another species?

A) behavioral isolation
B) genetic isolation
C) reduced hybrid viability
D) hybrid breakdown

Question 59

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?

A) reinforcement of isolating mechanisms
B) fusion of species
C) stability of species
D) development of polyploidy

Question 60

A narrow hybrid zone separates the toad species Bombina bombina and B. variegata. A genetic study identified a locus where one allele (R) occurred in all B. variegata, occurred in a few B. bombina at the edge of the hybrid zone, and was replaced totally by another allele (r) in B. bombina that lived far from the hybrid zone. Which of the following statements is most likely to be accurate with regard to the frequency of V1 in the hybrid zone?

A) The frequency of R is quite low in hybrids near the range of B. variegata.
B) The frequency R is constant across the hybrid zone.
C) The frequency of R declines in hybrids as animals are sampled closer to the range of B. bombina.
D) The frequency of R high across the hybrid zone.

Question 61

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?

A) The two forms interbreed often in nature, and their offspring survive and reproduce well.
B) The two forms live in similar habitats and have similar food requirements.
C) The two forms have many genes in common.
D) The two forms are very similar in appearance.

Question 62

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 ________.

A) 14
B) 16
C) 28
D) 56

Question 63

According to the punctuated equilibria model, ________.

A) given enough time, most existing species will branch gradually into new species
B) 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
C) most evolution occurs in sympatric populations
D) speciation is usually due to a single mutation

Question 64

Which of the following factors would not contribute to allopatric speciation?

A) The separated population is small, and genetic drift occurs.
B) The isolated population is exposed to different selection pressures than the ancestral population.
C) Different mutations begin to distinguish the gene pools of the separated populations.
D) Gene flow between the two populations is extensive.

Question 65

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) habitat isolation
B) temporal isolation
C) behavioral isolation
D) gametic isolation