Chapter 24 Mastering quiz bio 2

QUANTITATIVE If one species (2n = 14) crosses with another species (2n = 12), producing an allopolyploid offspring, what is the ploidy of the offspring? -2n = 14 -2n = 12 -2n = 7 + 6 = 13 -4n = 28 +24 = 52

2n = 7 + 6 = 13

What is genetic drift? -The physical splitting of a habitat -The production of an evolutionarily independent group of organisms -A change in allele frequencies caused by random events -The motion of continental plates over time

A change in allele frequencies caused by random events Genetic drift is a random change in allele frequencies over time.

How might a tetraploid emmer wheat plant and a diploid wild wheat plant give rise to a new hexaploid wheat species? -A tetraploid emmer wheat fuses with a diploid wild wheat. -These two species are unable to mate because they have different chromosome numbers. -A diploid emmer wheat gamete will self-fertilize and then fuse with a haploid wild wheat. -A diploid emmer wheat gamete fuses with a haploid wild wheat gamete to form a triploid individual that undergoes autopolyploidy to form a hexaploid individual.

A diploid emmer wheat gamete fuses with a haploid wild wheat gamete to form a triploid individual that undergoes autopolyploidy to form a hexaploid individual. Gametes will typically possess half of the chromosomes of their parents.

Which statement is correct? -A monophyletic group may include an ancestral population and some, but not all, of its descendants. -A monophyletic group consists of all of the descendants of an ancestral population. -A monophyletic group consists of an ancestral population, all of its descendants, and only those descendants. -A monophyletic group is a theoretical idea that does not exist in the real world.

A monophyletic group consists of an ancestral population, all of its descendants, and only those descendants.

Which event would result in allopatric speciation? -A flood that separates a population of frogs onto opposite sides of a large lake for a few months. -Development of different antler sizes between male and female reindeer -Migration of birds back and forth between the mainland and an island -An earthquake that isolates a population of rodents on a mountain from other populations of rodents

An earthquake that isolates a population of rodents on a mountain from other populations of rodents Allopatric speciation can occur as a result of vicariance events.

Which of the following statements about autopolyploid individuals is correct? -Autopolyploid individuals contain more than two sets of chromosomes. -Autopolyploid individuals can be produced from nondisjunction events in mitosis. -Autopolyploid individuals result from a mating between individuals of different species. -Autopolyploid individuals are formed by combining three gametes.

Autopolyploid individuals contain more than two sets of chromosomes. All polyploid individuals contain more than two sets of chromosomes

Which concept(s) for identifying species cannot be applied to asexual or fossil species? -Morphospecies concept -Phylogenetic species concept -Biological species concept -All of the listed responses are correct.

Biological species concept

Which of the following is a correct comparison between the speciation of the trumpeters of the Amazon and the ongoing divergence of the maggot flies of North America? -Both events involved populations that were overlapping in their ranges. -Both events involved a large geographic barrier between populations. -Both events resulted from barriers to gene flow that arose between populations as well as mutations, natural selection, and genetic drift that occurred in those populations. -Both events involved polyploidization.

Both events resulted from barriers to gene flow that arose between populations as well as mutations, natural selection, and genetic drift that occurred in those populations. In trumpeters the barrier is geographic: the rivers separating populations. In the maggot flies it is habitat preference and temporal differences that prevent gene flow between the populations.

If autopolyploidy is responsible for the formation of a tetraploid grape (with extra-large fruit) from a diploid population (with smaller fruit), which of the following events must have occurred? -Halving of chromosome number in the diploid population -Mating of diploid individuals to individuals from a different species of grape -A point mutation that produces extra-large fruit -Doubling of chromosome number in the diploid population

Doubling of chromosome number in the diploid population

True or false? Speciation is a slow process. Justify your answer. -False. Speciation is sometimes a slow process, but can occur rapidly, such as the formation of a new species of Tragopogon by allopolyploidy in a single generation. -False. Speciation is quite a rapid process in comparison to the formation of larger taxa, such as genus, order or class. -True. Speciation occurs slowly because to form a new species, a significant accumulation of genetic changes should happen; it could take thousands of years.

False. Speciation is sometimes a slow process, but can occur rapidly, such as the formation of a new species of Tragopogon by allopolyploidy in a single generation.

When the ranges of two different species meet, a stable "hybrid zone" occupied by hybrid individuals may form. How is this possible? -One species has a selective advantage, so as hybridization continues, the other species will go extinct. -Hybrid individuals may have reduced fitness and thus be strongly selected against. -Hybrid individuals are always allopolyploid and are thus unable to mate with either of the original species. -Hybrid individuals may have intermediate characteristics that are advantageous in a given region.

Hybrid individuals may have intermediate characteristics that are advantageous in a given region.

Which mechanism causes postzygotic reproductive isolation? -Hybrid sterility -Mechanical isolation -Temporal isolation -Habitat isolation

Hybrid sterility Sterile hybrids would isolate the two populations, but zygotes can still be formed.

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? -Decreased fitness of small-beaked birds, creating a new species -Decreased fitness of the insects, allowing the birds to catch them more easily -Increased fitness of large-beaked birds, leading to natural selection -Increased fitness of the large-beaked birds, creating a new species

Increased fitness of large-beaked birds, leading to natural selection Birds with larger beaks are better able to survive in the new environment.

What occurs in a hybrid zone? -Extinction -Reinforcement -Interbreeding -Disruptive selection

Interbreeding A hybrid zone is formed by members of a population mating with individuals of a different population.

What is one disadvantage of this approach? -It is very difficult to determine whether morphological differences among fossils represented normal variation within populations or meaningful differences among species. -It is difficult to determine the age of fossils and thus to define the order of speciation of human's ancestors. -t is quite complicated to evaluate the causes that lead to the speciation of ancient humans. -It is impossible to determine whether the differences were left on fossils by some catastrophe or by time or they are meaningful differences among species.

It is very difficult to determine whether morphological differences among fossils represented normal variation within populations or meaningful differences among species.

How is a hybrid zone most likely to change over time if hybrid offspring have higher fitness than both parental populations? -It should expand into the range of only one parental population. -It should disappear. -It should get smaller but not disappear. -It should expand into the ranges of both parental populations.

It should expand into the ranges of both parental populations.

Which of the following situations is a result of reproductive isolation caused by differences in timing? -Males and females of one species breed in oak trees, whereas males and females of a closely related species breed in maples. -Males and females of one species breed in early springtime, whereas males and females of a closely related species breed in early summer. -Males and females within a species are active at different times of day. -Males and females of one species form lifetime pair bonds, whereas males and females of a closely related species are polygamous.

Males and females of one species breed in early springtime, whereas males and females of a closely related species breed in early summer. The seasonal difference in breeding season would mean that members of one species would never have the opportunity to mate with the other species.

Paleontologists studying fossilized therapsids (a group of mammal-like reptiles that are now extinct) would probably use which of the following species concepts? -Biological species concept -Phylogenetic species concept comparing DNA -Morphospecies concept -None of the listed responses is correct. Fossil species cannot be classified

Morphospecies concept Paleontologists normally have little choice but to use morphospecies concepts because they cannot test reproductive isolation or the genetic relatedness of most fossils.

Imagine that the human genome project has shown that individuals from a light-skinned population can exhibit greater similarity in DNA sequence with individuals from a dark-skinned population than they do with other individuals in the light-skinned population. Should these light- and dark-skinned human populations be considered separate species under the phylogenetic species concept? Why or why not? -Yes. The DNA sequence data conclusively show that they represent different clades. -Yes. Regardless of the DNA sequence data, they have different skin colors. -No. The DNA sequence data do not support the conclusion that they represent different clades. -Maybe. It depends on whether the two populations can interbreed and produce viable offspring.

No. The DNA sequence data do not support the conclusion that they represent different clades.

Which is the first step in allopatric speciation? -Physical isolation of two populations -Differential natural selection in different environments -Genetic divergence due to mutation -Loss of genetic variation due to genetic drift

Physical isolation of two populations Geographic isolation of two populations is the first step in allopatric speciation.

Which of the following statements about reinforcement is true? -Reinforcement is a type of natural selection -Reinforcement decreases the morphological difference between two incipient species. -Reinforcement is also called dispersive selection. -Reinforcement increases the number of intermediate phenotypes.

Reinforcement is a type of natural selection Reinforcement is a type of natural selection called disruptive selection, which favors extreme phenotypes over intermediate phenotypes.

Which description of reinforcement is correct? -Reinforcement is the loss of genetic differences between two populations due to gene flow. -Reinforcement is natural selection against interbreeding and production of hybrid offspring. -Reinforcement leads to development of a hybrid zone. -Reinforcement is the genetic divergence of populations in different environments.

Reinforcement is natural selection against interbreeding and production of hybrid offspring.

Which statement about polyploidy is correct? -Speciation by polyploidy is unknown in plants -Polyploid and diploid populations hybridize readily. -Speciation by polyploidy may be almost instantaneous. -Triploid individuals can never reproduce successfully.

Speciation by polyploidy may be almost instantaneous.

Which of the situations below describes vicariance? -American bullfrogs expand their range into British Columbia. -A small group of finches is blown from the mainland to a recently formed volcanic island. -Four moose are transported from New Brunswick to Newfoundland, where they establish a large population. -The Grand Canyon forms, separating two populations of squirrels on the North Rim and the South Rim.

The Grand Canyon forms, separating two populations of squirrels on the North Rim and the South Rim.

How do autopolyploidy and allopolyploidy differ? -Autopolyploidy is sympatric, while allopolyploidy is allopatric. -Autopolyploidy is a mechanism of speciation in plants, while allopolyploidy is a mechanism of speciation in animals. -Only autopolyploidy involves an increase in chromosome sets. -The chromosomes of an autopolyploid individual come from the same species, while an allopolyploid individual has sets of chromosomes from different species.

The chromosomes of an autopolyploid individual come from the same species, while an allopolyploid individual has sets of chromosomes from different species.

Which of the following is considered by some to be a disadvantage of the phylogenetic species concept? -The phylogenetic species concept produces many more species, a number of which are not easily distinguishable based on morphology. -The phylogenetic species concept characterizes species based on ancestry, and only monophyletic groups are recognized. -The phylogenetic species concept utilizes many characteristics to establish relatedness between different species. -The phylogenetic species concept can be used for any organism, including those that reproduce asexually.

The phylogenetic species concept produces many more species, a number of which are not easily distinguishable based on morphology. The phylogenetic concept recognizes many more taxa.

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 itsoriginal 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. -The populations will be able to interbreed even though they are different species. -The populations were sympatric while they diverged. -The birds were separated by a vicariance event.

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

When two populations come into contact after a long period of divergence in allopatry, which of the following is the LEAST likely possibility? -The two populations meet and hybrid offspring from the two populations have reduced fitness. -The two populations meet and mating does not produce any offspring. -The two populations meet and there have been no genetic changes between the populations. Each population is identical to the population before the separation. -The two populations meet and form a hybrid zone where both species interbreed and form viable offspring.

The two populations meet and there have been no genetic changes between the populations. Each population is identical to the population before the separation. It is highly unlikely that no changes have occurred. There must have been some mutation, or effects of drift, while the populations were separated.

True or False? Gene flow decreases the divergence of populations. -True -False

True

Which of the following would be a good example of prezygotic reproductive isolation? -Two bird species live in the same area and, though similar in plumage, engage in dramatically different courtship dances. -Two frog species meet and can mate with each other, but the hybrid offspring are infertile. -Young males hang around the edges of leks and surreptitiously breed with females; older males establish territories in the leks. -Two beetle morphologies can be distinguished, but they are capable of interbreeding in areas where both morphologies are found.

Two bird species live in the same area and, though similar in plumage, engage in dramatically different courtship dances. Courtship dances often contain information about species identity. If the correct dance is not performed, mating will not occur and no zygote will be formed.

Before the application of DNA sequencing to fossils, which species concept was most useful for distinguishing human fossils? -morphospecies concept -biological concept -phylogenetic species concept -none of the above

morphospecies concept

Why was mitochondrial DNA so useful in the study of the hybrid zone between Townsend's warbler and hermit warblers? -mtDNA is maternally inherited, so the researchers were able to discover that most hybrids resulted from Townsend's males mating with hermit females. -mtDNA is inherited from both parents, like most of the nuclear genetic material. Any gene could have been used in this study. -mtDNA is easy to extract, so the researchers could obtain lots of genetic information about the hybrids. -mtDNA shows that reinforcement has been occurring within this hybrid zone.

mtDNA is maternally inherited, so the researchers were able to discover that most hybrids resulted from Townsend's males mating with hermit females. Hybrid warblers always contained hermit mitochondria, suggesting that hermit females would mate with Townsend's males. If Townsend's females mated with hermit males, then some hybrids would contain Townsend's mitochondria.

Biological, morphological, and phylogenetic species concepts allow biologists to identify evolutionarily independent groups because they all rely on criteria indicative of _____ -no gene flow between populations -postzygotic isolation between populations -prezygotic isolation between populations -geographical isolation between populations

no gene flow between populations

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 -False

true Allopatric speciation may occur when populations are separated geographically; this type of speciation can begin with a vicariance event, in which a geographic barrier such as water isolates a population, or a dispersal event, in which a subsetof a population migrates to a different habitat.