Mastering HW - Exam 1 Review
Which of the following statements about the evolution of Anolis lizards in the Caribbean islands is true?
The phylogeny of ecomorphs on a given island reveals that adaptive radiation has taken place
What do the 1's and 0's represent in this data matrix?
the presence or absence of a trait in a taxon
True or false? It would be difficult to assess whether the drug-susceptible or drug-resistant phenotype in a population of Mycobacterium tuberculosis was more fit in an environment without antibiotics.
True
Does this model show that evolution has occurred? Select the best answer.
Yes; the allele frequencies have changed.
Evolution of shorter legs in anole lizards placed on small, hurricane-scrubbed islands is an example of which type of evolution?
microevolution
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
Calculate the allele frequencies in the iguana population following the mutation event.
0.95 G, 0.05 g
Humans are diploid and have 46 chromosomes (or two sets). How many sets of chromosomes are found in each human gamete?
1
A particular diploid plant species has 48 chromosomes, or two sets. A mutation occurs and gametes with 48 chromosomes are produced. If self-fertilization occurs, the zygote will have _____ set(s) of chromosomes.
4
Review the video to determine which statement(s) correctly describe the origin of antibiotic resistance. Drag "True" or "False" to the end of each statement.
A random mutation enabled resistance prior to exposure to the drug treatment. True A random mutation enabled resistance after exposure to the drug treatment. False The drug caused some of the bacterial cells to mutate and become resistant. False Some of the bacterial cells mutated their genes on purpose because they wanted to survive the drug treatment. False
Drag a number to complete each sentence. Numbers may be used once, more than once, or not at all.
An example of a single fork is represented by the shaded area numbered 2. An example of a place in the tree where a speciation event occurred is represented by the shaded area numbered 2. An example of a most recent common ancestor of two descendant branches is represented by the shaded area numbered 2. An example of a node is represented by the shaded area numbered 2.
What would happen if another species came to the island? Given what you know about the birds on Daphne, predict what would happen to the native species with each type of colonizing finch. Assume that the colonizing bird is superior to the native birds at foraging.
Blue (immediate consequences): 1. Small native birds starve so only the larger natives pass on their genes 2. Native birds with genes for larger beaks starve. 3. Native birds starve. White (Native populations respond by): 1. Getting larger over generations 2. Getting smaller over generations 3. Population numbers drop Red: 1. The native species begins to overlap somewhat with Big Birds in morphological space. 2. The native species begins to overlap somewhat with big birds in morphological space 3. The native species goes extinct on the island.
In all of these phylogenetic trees, the gain or loss of a trait is represented by a red trait mark. These marks are a way of showing change---that is, evolution. Which tree does the best job of showing which branches are evolving?
C - Lines through each branch
Which of the following are basic components of the Hardy-Weinberg model?
Frequencies of two alleles in a gene pool before and after many random matings
Which hypothesis do these results support?
Glucose aversion is an incompletely dominant trait.
Which of the following evolutionary forces consistently results in adaptive changes in allele frequencies?
Selection
Which of the following statements describes the evolution by natural selection of Mycobacterium tuberculosis bacteria in their new environment?
The drug-resistance trait is an adaptation to the environment in which human hosts are medicated with the antibiotic rifampin.
What is the frequency of the A1 allele in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals?
The frequency of the A1 allele is 0.3.
Why are the large finches now living on the Galápagos Islands different from the original source population from a nearby island?
The separation of habitats reduced gene flow between the populations. Genetic drift occurred in the two populations. Natural selection favored individuals that were more fit in the new environment. All three answers are correct.*
Scientific evidence documents the pattern of evolution. The evidence exists in a variety of categories, including direct observation of evolutionary change, the fossil record, homology, and biogeography. Sort the following examples into the correct categories.
direct observation of evolutionary change: development of drug resistance in bacteria fossil record: discovery of transitional forms of horses discovery of shells of extinct species homology: similarities in mammalian forelimbs same genetic code in fireflies and tobacco plants vestigial pelvis in right whales biogeography: similarity of endemic island species to nearby mainland species the high concentration of marsupial species in Australia
What prevents speciation from occurring in sympatric populations?
gene flow
Most polyploid plants arise as a result of
hybridization
Which of the following is an example of an adaptation in anole lizards?
long legs in the anole lizards that live primarily on the ground and tree trunks
Generation-to-generation change in the allele frequencies in a population is _____.
microevolution
Based on this information, do you still think lions and tigers are separate species? (All responses will be marked correct.)
no
Examine this Punnett square. What does the number 0.6 refer to?
the gamete allele frequency p
If you wanted to draw a population of butterflies to show variation in the relative sizes of their forewings and hindwings, which style of drawing would be the most efficient to use?
B - Simple cartoon
Which organisms are not examples of an adaptive radiation?
Mammals and reptiles in the post-dinosaur age
This model shows which process? (fishes with x's on the first photo)
Natural Selection
the process by which haploid gametes form a diploid zygote.
Fertilization
Iridium is a component of cosmic dust that rains down upon the earth at a constant rate. Why did Luis Alvarez suggest measuring iridium levels in the K-T boundary?
He was looking for a way to determine how quickly the layer had been deposited.
True or false? Heterozygote advantage refers to the tendency for heterozygous individuals to have better fitness than homozygous individuals. This higher fitness results in less genetic variation in the population.
False
Which phylogenetic tree shows that lactation--the production of milk to feed young--is a homologous trait in humans, dogs, and bats (but not in birds and lizards)?
C - milk on second branch, superior
Which phylogenetic tree shows that wings occur only in bats and birds but are not homologous?
Common Sense
No two species of anoles lizards living in the same geographical location have dewlaps of the same size, shape or color. Why?
Differences in dewlaps keep different anole species reproductively isolated, even when they live together. Male anole lizards use dewlaps to court females. Dewlap color is under strong selection. Dewlaps that contrast with a lizard's environment are more effective for communication. Female anole lizards distinguish males of their own species from males of other species by their dewlaps.
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
What kinds of characters can you use to create a data matrix for estimating phylogenetic trees?
any heritable trait
Does the ability of a Mycobacterium tuberculosis cell to infect a new host depend on its drug-resistant phenotype?
No, drug-susceptible cells and drug-resistant cells are equally likely to infect a new host.
Which of the following statements about reinforcement is true?
Reinforcement is a type of natural selection.
Women often have complications during labor while giving birth to very large babies, whereas very small babies tend to be underdeveloped. Which kind of selection is most likely at work regarding the birth weight of babies?
Stabilizing Selection
The different finch species found on the Galápagos Islands probably arose as a result of
adaptive radiation
Feathers either play a role, or may have played a role, in _____.
extended hops flight courtship gliding all of these*
True or false? A mating between a tetraploid individual and a diploid individual produces biologically fit offspring.
false
True or false? The last ice age produced many different species mainly because populations dispersed and colonized new habitats.
false
Which evidence is consistent with the asteroid impact hypothesis? Select all that apply.
shocked quartz in the K-T boundary layer spherules, glass-like beads in the K-T boundary layer iridium tektites, a type of melted rock
Which term is used to describe populations that live close enough to interbreed?
sympatry
Given what you've learned about the biological species concept, should G. fortis and G. scandens continue to be considered separate species?
yes
What is the frequency of the A1A2 genotype in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals?
0.4
Calculate the allele frequencies in this population of palm trees.
0.5 F, 0.5 f
Long necks make it easier for giraffes to reach leaves high on trees, while also making them better fighters in "neck wrestling" contests. In both cases, which kind of selection appears to have made giraffes the long-necked creatures they are today?
Directional selection
A hypothetical population of 200 cats has two alleles, TL and TS, for a locus that codes for tail length. The table below describes the phenotypes of cats with each possible genotype, as well as the number of individuals in the population with each genotype. Which statements about the population are true?
Heterozygotes make up 20% of the population. Homozygotes make up 80% of the population. In the entire cat population, 60% of the alleles are TS. In the entire cat population, the frequency of the TL allele is 0.4. Assuming random mating, each gamete has a 40% chance of having a TL allele and a 60% chance of having a TS allele.
Drag "True" or "False" to the end of each statement.
If Chum salmon were added as a sister group to Pink salmon, Pink salmon would become more distantly related to Sockeye salmon. False Arctic graylings are more closely related to Atlantic salmon than to Pink salmon because there are only two nodes between graylings and Atlantic salmon but four nodes between graylings and Pink salmon. False Arctic graylings are more closely related to Atlantic salmon than to Pink salmon because the labels are closer. False Coho salmon are as closely related to Arctic graylings as Pink salmon are to Arctic graylings because Pink and Coho salmon share a common ancestor at the node marked by a dot. True If Sockeye salmon were removed from the tree, Pink salmon would become more closely related to Arctic graylings. False
Interpret the phylogenetic tree.
Magnolias only have trait C. False The common ancestor marked by the dot had all five traits. False Trait C occurs only in magnolias. True Trait D is homologous in all of the taxa except mosses. True Trait B is homologous in pines, cedars, and cacao. False Trait E is homologous in magnolias, roses, and cacao. True
Which of the following evolutionary forces could create new genetic information in a population?
Mutation
How can an allopolyploid plant become a biologically fit new species?
Nondisjunction event during mitosis
What was the main selective pressure behind the evolution of different Anolis lizard species in the Caribbean?
Specific ecological niches
Which of the following statements is not a part of the Hardy-Weinberg principle?
The genotype frequencies in the offspring generation must add up to two.
What conclusion can you draw from these data? Drag the correct answer into each blank.
The observed number of glucose averse cockroaches is much higher than expected. The data support the conclusion that the glucose aversion trait has become more common in the population as a result of adaptive evolution.
What is a gene pool?
a hypothetical collection of all the possible alleles in a population
Mass extinctions create conditions that promote
adaptive radiation
The appearance of an evolutionary novelty promotes
adaptive radiation
Mutant tetraploid plants
are unable to interbreed with a diploid plant
Which characteristic was NOT advantageous for organisms in the million years after the catastrophic asteroid impact?
large body size
The three major mechanisms of evolution differ in how they work, and as a result often have different effects on a population. Review your understanding of natural selection, genetic drift, and gene flow by sorting the statements below into the correct bins.
natural selection: consistently causes a population to become better adapted to its environment a result of differential success in reproduction cannot cause a harmful allele to become more common genetic drift can result from the founder effect can result from the bottleneck effect causes allele frequencies to fluctuate randomly gene flow can introduce new alleles into a population's gene pool a result of the movement of fertile individuals or their gametes
Which tree does the best job of highlighting some of the ancestors of humans?
C - Tree with dots on it
A hypothetical population of 300 wolves has two alleles, FB and FW, for a locus that codes for fur color. The table below describes the phenotype of a wolf with each possible genotype, as well as the number of individuals in the population with each genotype. Which statements accurately describe the population of wolves?
Based on the equation for Hardy-Weinberg equilibrium, the expected number of wolves with the FBFB genotype is 12. Based on the equation for Hardy-Weinberg equilibrium, the expected number of wolves with the FBFW genotype is 96. The population may be evolving because the actual number of individuals with each genotype differs from the expected number of individuals with each genotype. The population is not at Hardy-Weinberg equilibrium.
Use this Punnett square to calculate the predicted genotype frequencies of the offspri
MM:p2=0.36 Mm:2pq=0.24+0.24=0.48 mm:q2=0.16
Evaluate this statement: Gene flow increases the genetic divergence of populations.
This statement is false. Gene flow reduces the divergence of populations.
Calculate the allele frequencies in this fish population.
0.46 A, 0.54 a
Humans are diploid and have 46 chromosomes. How many chromosomes are found in each human gamete?
23
Suppose that Gene BB occurs in a sea turtle gene pool where the frequency of the B1B1 allele is 0.5 and the frequency of the B2B2 allele is 0.4. What is the frequency of the B3B3 allele, assuming that there are only three alleles in the population?
The frequency of B3=0.1B3=0.1 because 0.5+0.4+?=10.5+0.4+?=1.
True or false? Convergent evolution is said to have occurred if the mouse species on two islands with similar habitats are found to have similar characteristics even though they originated from different species that did not have these characteristics.
True
Which Anolis lizard ecomorph has long legs?
Trunk/ground
rapid speciation under conditions in which there is little competition
adaptive radiation
What would be the ploidy of the viable gametes produced by a tetraploid individual if nondisjunction of all chromosomes occurred in meiosis I?
tetraploid
What was the critical piece of evidence that supported the hypothesis that an asteroid struck Earth 65 million years ago?
the Chicxulub crater in Mexico
How do foraminifera found in rock layers above the K-T boundary compare to those in rock layers below?
Foraminifera above the boundary are smaller and less diverse than those below.
Which of Darwin's postulates does this information address? Drug resistant M. tuberculosis cells have a mutation in the rpoBrpoB gene that is passed onto offspring.
#2
What did the Grants observe about 5110? Drag the terms on the left to the appropriate blanks on the right to complete the sentences.
Bird 5110 was larger than other birds on the island, which earned him the nickname Big Bird. The song of 5110 was different from the songs of other bird species on the island. The Grants performed genetic testing on 5110 and determined that he was homozygous for a rare allele. They also determined that he was hatched on a neighboring island.
Which phylogenetic tree highlights the most recent common ancestor of all animals with four limbs (where limbs include legs, arms, and wings)?
C - dot on second connection
True or false? The evolution of different ecomorphs on the Caribbean islands is an example of stabilizing selection.
False
DNA evidence suggests that anole lizard species from the four largest Caribbean islands are related as shown in the figure. Which statement is true?
Different body types evolved repeatedly and independently on each island.
What is the most important characteristic of anole lizard species that keeps members of one species from mating with members of another species?
Different species living in the same habitat have different dewlaps.
Based on the results of the feeding experiment, what conclusions can you draw? Select all that apply. (For help interpreting the results, see the hints.)
Roaches ate about the same amount from the dish with no hydramethylnon as they did from the control dish. Roaches ate about the same amount from the dish with no oleic acid as they did from the control dish. Roaches are refusing corn syrup.
Jonathan Losos and colleagues conducted experiments on small, hurricane-swept islands as "natural laboratories." Which of the following statements is true?
Natural selection can lead to rapid changes. The average leg length of lizard populations decreased within a few generations. There are many small islands with similar environments, meaning that researchers can repeat their experiments and observations in several locations. Islands scrubbed by hurricanes allow researchers to introduce new lizard populations and observe their evolution.
What observations and evidence have Jonathan Losos and his colleagues gathered to support the theory of natural selection?
On each of the four large Caribbean islands, Losos observed the same distribution of anole lizard body types. DNA evidence suggests that the different lizard body types (twig, grass, etc.) evolved independently on each of the four large Caribbean islands. When Losos and colleagues transplanted tree-dwelling anoles to small, hurricane-scrubbed islands without trees, the lizards evolved to have shorter legs after only a few generations.
Populations evolve for many reasons. Suppose there is a population of plants that have either purple flowers or white flowers, and the allele for purple flowers is dominant. This means that plants with two purple alleles have purple flowers. Plants with one purple allele and one white allele also have purple flowers. Only plants with two white alleles have white flowers. For each event or condition described below, answer the following questions. Which mechanism of evolution is at work? How does this event affect the population's gene pool? Do the frequencies of the two alleles change, and if so, how?
Red (mechanism): a. natural selection c. genetic drift e. genetic drift g. natural selection i. gene flow White (effect on allele frequencies): b. frequency of white allele increases d. frequency of purple allele increases f. allele frequencies change but not predictably h. frequency of purple allele increases j. frequency of white allele increases
The bacteria in the video are color-coded. The "red" bacteria had the normal rpoBrpoB gene. Thus, RNA polymerase was vulnerable to drug treatment. The "blue" bacteria had the mutant rpoBrpoB gene. Thus, RNA polymerase was resistant to drug treatment. Which statement best describes the population of bacteria?
Red and blue are used to track two versions of the rpoBrpoB gene in this patient, but many other variations are likely to occur in this population of bacteria.
Small Aristelliger lizards have difficulty defending territories, but large lizards are more likely to be preyed upon by owls. Which kind of selection acts on the adult body size of these lizards?
Stabilizing Selection
Using the biological species concept as your guide, sort the following observations based on whether they support the notion that the Big Bird lineage is a separate species or whether they refute the notion that it is a separate species.
Supports separate species: Big Birds have their own unique call. There is no gene flow in or out of the Big Bird population. Big Bird males hold territories in and around territories of other species but breed only with Big Bird females. Refutes separate species: Big Bird males can breed with G. fortis females.
In this exercise, you will use the cytochrome c oxidase I (COI) gene to investigate relationships among salmon species. (This gene encodes a protein that functions in the mitochondrial electron transport chain.) You will compare the COI gene sequences from your salmon test samples to the standard sequences for each salmon species. In order for the COI gene to be useful for distinguishing among the different salmon species, which three statements must be true?
The COI gene must be variable enough that there are at least a few differences between each salmon species. The COI gene must be conserved enough that the sequences can be aligned for comparison. The COI gene must be conserved enough that the same PCR primers work for all the species being tested.
Select the statements about the K-T boundary that are true.
The K-T boundary dates to 65 million years ago (when the dinosaurs disappeared). The K-T boundary separates rock layers of the Cretaceous period from those of the Tertiary period. The K-T boundary in Zumaia, Spain is sharp--representing an abrupt change in the marine ecosystem.
Which factors are often associated with speciation events in island-dwelling species, such as the Galápagos finches studied by Rosemary and Peter Grant?
Dispersal and colonization
Black-bellied seedcrackers have either small beaks (better for eating soft seeds) or large beaks (better for hard seeds). There are no seeds of intermediate hardness; therefore, which kind of selection acts on beak size in seedcrackers?
Disruptive Selection
Drag "True" or "False" to the end of each statement.
Dragonflies are more closely related to crickets than to cockroaches because the labels are closer. False Dragonflies are more closely related to crickets than to ants because the labels are closer. False Ants are as closely related to dragonflies as crickets are to dragonflies because ants and crickets share the common ancestor marked by the dot. True If cockroaches were removed from the tree, crickets would become more closely related to ants. False If butterflies were added to the tree as a sister group to moths, beetles would become more distantly related to flies. False Ants are more closely related to beetles than to flies because there are only two nodes between ants and beetles but three nodes between ants and flies. False
During the rainy season, and just as the dry season starts, food is abundant for all finches. However, as the dry season wears on, the seeds they eat become harder to find and competition becomes an important factor in survival. When a serious drought lasting 2.5 years hit Daphne, the only finches that survived were the ones that could find enough food; seeds that they could not split open did not contribute to survival. Heavy mortality in a population means there is strong selection for heritable traits that help individuals survive and reproduce. For example, G. magnirostris eat large seeds, and G. magnirostris can outcompete all other finches. The Big Birds and G. fortis fight over smaller seeds and water holes, but the Big Birds are dominant to G. fortis because they are almost twice the size of G. fortis.
Immediate effects --> Long-Term effects 1. Individuals with large beaks die. --> Beaks become smaller in the population. 2. Most individuals thrive. --> Beaks remain large in the population. 4 Many individuals outcompete smaller birds for large seeds. --> Beaks remain the same size, and the population fills a larger niche, eating a greater variety of seeds.
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
Interpret the model of two moss populations that occur only at certain altitudes in the mountains.
The allele frequencies of moss on the taller mountain are 0.86 A and 0.14 a. False This model suggests that there is a barrier to gene flow between high-altitude populations. True The color code in this model represents genotypes. True This model shows genetic drift in one population. False This model shows that evolution is occurring. True This model shows the origin of a new allele via mutation. True
Review the video to determine what evolved in this drug-resistance scenario. Drag "True" or "False" to the end of each statement.
The population of bacterial cells within the patient's lungs evolved. True Individual bacterial cells within the patient's lungs evolved. False The human population evolved. False The patient with tuberculosis (Bob) evolved. False The lung cells within the patient evolved. False
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.
Interpret the phylogenetic tree.
The single branch for bacterium could be expanded to show the relationships of many species of bacteria. True This tree shows that a bacterium is the lowest form of life. False This tree could be rotated so that the branch for bacterium is on the top rather than the bottom of the tree. True Less evolution occurs in the long branches than occurs in the short branches. False This tree shows that bacteria evolve into green algae, which evolve into plants, and so on. False The bacteria that are alive today are the common ancestors of all other organisms. False
Which of the following statements is an accurate combination of postulates 1 and 2 of natural selection?
a. Heritable variation does not exist among individuals in a population. b. Heritable variation exists for traits among individuals in a population. c. Environmental variation exists for traits among individuals in a population. d. Drug resistance exists among all individuals in a population. B
Which of the following statements is an accurate combination of postulates 3 and 4 of natural selection?
a. Individuals experience unlimited success in their ability to survive or reproduce. b. Individuals experience no success in their ability to survive or reproduce. c. Individuals experience differential success in their ability to survive or reproduce due to differences in certain traits. d. Individuals experience uniform success in their ability to survive or reproduce. C
Identify the four postulates of natural selection. Select all that apply.
a. Individuals in a population all possess the same traits. b. Individuals in a population vary in the traits they possess. c. All individuals in a population have equal reproductive success. d. Survival and reproductive success are variable among individuals in a population. e. Some trait differences are heritable. f. Individuals with certain traits are more likely to survive and reproduce. B,D,E,F
Which of these terms applies to an organism with extra sets of chromosomes?
polyploid
Which drawing of a population of bacteria does the best job of illustrating Darwin's second postulate, that some variation among individuals is heritable? (The color red represents the ability of the bacteria to digest the sugar lactose.)
A - all same color
Birds vary in many traits. Select a set of three cartoons that focus just on variability in leg length. Select three.
A,B,D
Which of these trees show the same evolutionary relationships?
A,B,D - All but the one with names pointing to the top
Which of these trees show the same evolutionary relationships? Select all that apply.
A,D
Which of the following statements about adaptive radiation is correct?
Adaptive radiation occurs within a single lineage.
The scientific community was slow to accept the asteroid impact hypothesis. Why?
At the time, most geologists thought that the Earth changed slowly and gradually, and not by major catastrophes.
Given the data in this phylogenetic tree, what is the most likely source of Sample 1?
Atlantic salmon, because Sample 1 shares a more recent common ancestor with Atlantic salmon than with other salmon.
Drag "True" or "False" to the end of each statement.
1. Corn is more closely related to Sorghum than to Asparagus. True 2. Asparagus is more closely related to Papaya than to Orange. False 3. Peach is more closely related to Orange than to Papaya. False 4. Papaya is more closely related to Asparagus than Peach is to Sorghum. False
Each finch species has a distinct beak morphology (shape); that is, they have a distinct length and depth. Together, these two beak dimensions can determine what foods the birds will be able to eat. All finches eat seeds (among other things), but during the dry season, seeds are encased in dry, hard shells. The bigger, stronger muscles associated with larger beaks mean that large-beaked birds can crack open much harder shells to get to the nutritious seeds. The Grants collected the data represented in the graph. Each oval shows the distribution of bird beaks they measured in the population. F represents G. fortis, BB represents the Big Bird lineage, and M represents G. magnirostris. Use the graph to answer the following questions.
1. The beak length of G. fortis ranges from approximately 8 to 12 mm. 2. The mean beak depth of G. magnirostris is about 18 mm. 3. Based on beak dimensions, G. magnirostris likely eat the largest, hardest seeds. 4. Big Birds likely eat seeds that are larger than the seeds that G. fortis eat and smaller than the seeds that G. magnirostris eat. 5. A bird with a very long, shallow beak (like a hummingbird) would appear on the graph in the lower right quadrant.
Drag "True" or "False" to the end of each statement.
Speciation occurred more rapidly in tree A than in tree B. False Speciation occurred more rapidly in tree C than in tree A. False Speciation occurred more rapidly in tree D than in tree B. False
Which type of selection tends to increase genetic variation?
Disruptive selection
In the beetles described in the animation, there were two alleles for color, brown and green. Suppose that you discover a very small population of these beetles, consisting of the individuals shown below. How can you calculate the frequency of each allele in this population?
1. To calculate the frequency of the brown allele, count the number of brown alleles and divide by the total number of alleles in this population. 2. In this beetle population, the number of brown alleles is 8. 3. In this beetle population, the total number of alleles is 20. 4. The frequency of the brown allele in this beetle population is 0.4. 5. The frequency of the green allele in this beetle population is 0.6.
What is genetic drift?
A change in allele frequencies caused by random events
The island fox shares a common ancestor with the gray fox, Urocyon cinereoargenteus, which is found on the mainland. Both species have similar coloration and a diploid chromosome number of 66. One structural difference between the two species is the reduced size of the island fox, a feature known as dwarfism. The various island subspecies also differ from each other in size, number of tail vertebrae, and other characteristics. The phylogenetic tree below shows the evolutionary relationships between the island fox subspecies and the gray fox. Drag the labels to their appropriate locations on the tree. First, drag the labels of Group 1 to identify the common ancestors at the branch points. Next, drag one label of Group 2 to identify the homologous characteristic. Then, drag one label of Group 3 to identify the relationship between the two species.
Blue: a - ancestor of gray foxes and island foxes b -ancestor of Santa Rosa and San Miguel foxes most closely related d - ancestor of northern Channel Island foxes f - ancestor of southern Channel Island foxes g - ancestor of island foxes h - ancestor of Santa Catalina and San Clemente foxes Red: e - most closely related White: c - dwarfism
Interpret this student model of palm tree populations on two islands. Assume that at Time 1 (not shown) all the circles on Island 2 were white. Now, at Time 2, some are green.
The allele frequencies on the smaller island are 0.2 F, 0.8 f. True This model shows genetic drift. False To be accurate, the blue arrows would have to go both directions, not just from one island to the other. False The color code in this model represents phenotypes. False None of the palm trees on the larger island have the f allele. False This model shows the founder effect. False The blue arrows in this model represent gene flow. True The color code in this model represents genotypes. True
Drag "True" or "False" to the end of each statement.
The areas marked 2 and 3 are called nodes. True The vertical line marked 1 shows that speciation occurred very rapidly. False P. interjecta and P. dextralis are both descendants of a common ancestor symbolized by the area marked 3. True The birds represented by the area marked 3 belong to the species P. obscura. False A speciation event occurred at the area marked 2. True The areas marked 2 and 3 are called forks. True
In the United States today, about half of the corn crop is genetically engineered with a protein that is toxic to corn borers, an insect pest of corn. Which of the following conditions would be necessary for evolution of resistance to the toxic protein to occur in the corn borer?
The corn borer must have or generate (by mutation) heritable variation in resistance to the toxic protein. The resistant corn borers must survive better or reproduce more than nonresistant corn borers.
What genotype frequencies are expected under Hardy-Weinberg equilibrium for a population with allele frequencies of p = 0.8 and q = 0.2 for a particular gene?
The expected genotype frequencies are 0.64, 0.32, and 0.04 for A1A1, A1A2 , and A2A2 , respectively.
How could an asteroid impact kill off such a large number of different species all over the planet? Select all that apply.
The impact was so extreme that life at ground zero was vaporized. Debris from the impact orbiting around the Earth shielded sunlight, halting photosynthesis. Tsunamis, landslides, earthquakes, and heat caused by the impact killed organisms near the site of impact.
Apply what you have learned in the video to this new scenario focusing on four species of plants. Analyze the data matrix and phylogenetic tree to determine whether each statement is true or false.
The letter A could represent a morphological trait, such as the presence of flowers, or a molecular trait, such as a particular DNA nucleotide sequence. True Imagine if characters F, G, H, I, and J were added to the data matrix, showing that they are present in Plants 2 and 4 but absent in Plants 1 and 3. This additional information would increase your confidence in the relationships shown in the phylogenetic tree. True The phylogenetic tree shows correctly (based on the data matrix) that Plant 2 and Plant 4 are more closely related to each other than either is to Plant 3. True The phylogenetic tree shows correctly (based on the data matrix) that trait E is unique to Plant 4. False Five taxa are included in this data matrix. False
Evaluate this model of Darwin's postulates.
The model is comparing two species of flower: a species with short petals and a species with long petals. False The flowers grew longer petals because they needed to attract bees. False The top row of flowers indicates that there were only four flowers in the original population. False The X drawn over the flower shows that it did not survive. True The leaves, stems, and roots of the flowering plants were not included in the model for simplicity. True Flowers with short petals only mate with other flowers with short petals. False
Evaluate Chris's model of Darwin's postulates.
The model shows that in this population, grass plants vary in the height of their shoots. True The model suggests that in this population, at least some of the variation in shoot height is heritable. True The drawings must be life-like for the model to be helpful. False This model shows that the shorter and taller grass plants have the same reproductive success. False Grass plants have roots, but roots are not the focus of this model, so it is fine that Chris left them out. True
Three-spine sticklebacks are small fish that originated in the ocean and continue to exist there, but then some took up residence in hundreds of streams and freshwater lakes in the Northern Hemisphere. Would you expect to find different species in lakes today? Match the terms in the left column to the appropriate blanks in the sentences on the right. Not all terms will be used.
The sticklebacks are geographically isolated in the different lakes. This is a classic setting for allopatric speciation to occur. Whether the fish in the different lakes would be considered different species today depends on how much time has passed since the populations diverged and which species concept is used.
In a bell-shaped curve, the x-axis (horizontal direction) of the graph represents which of the following?
The value of a particular characteristic; characteristics of an organism can include such traits as size and color.
Which of the following statements about autopolyploid individuals is true?
They contain more than two haploid sets of chromosomes.
Interpret this model of a lake that was drained for irrigation. Assume that the death of certain fish was random with respect to their genotypes.
This model shows the bottleneck effect. True The arrow in this model represents gene flow. False The color code in this model may or may not represent fish color. True This model is not useful because the fish do not look very realistic. False This model is not useful because it shows far fewer individuals than would actually occur in a population in nature. False The allele frequencies at Time 2 are 0.25 A, 0.75 a. True This model shows genetic drift. True
True or false? The Hardy-Weinberg model makes the following assumptions: no selection at the gene in question; no genetic drift; no gene flow; no mutation; random mating.
True
Based on their observations and the data they collected, the Grants concluded that evolution by natural selection had occurred in the medium ground finch population. The increase in the average beak size of the offspring was a direct result of the change in the food supply during the drought. In order to have reached this conclusion, the Grants must have either assumed or proven that several other facts about the finch population were true. Which statements represent information that must be true in order for the Grants conclusion to be correct?
a. Birds that could eat larger, tougher seeds survived and reproduced during the drought. b. Beak size varies among the birds in the finch population under study. c. Beak size is an inherited trait in the finch population under study. d. An individual finch's beak size can change depending on the size of the seeds it eats. e. The drought caused a mutation that led to larger beak sizes in the finch population. A,B,C
Some monkey flowers (Mimulus guttatus) living near the sites of copper mines can grow in soil containing high concentrations of copper, which is toxic to most plants. Copper tolerance is a heritable trait. The map below shows the area near an old copper mine, which contaminated the nearby soil with copper. A stream flows past the mine toward the lake at the bottom right of the map. Use the map to determine which of the statements below are true. Select the three statements that are true.
a - Nearly 100% of monkey flowers growing in copper-contaminated soil are copper tolerant. b - If you were to test monkey flowers growing on the shore of the lake, you would expect nearly 100% of them to be copper tolerant. c - Copper-tolerant plants are found only in contaminated soils. d - The population that existed before mining must have included both copper-tolerant and copper-intolerant plants. e - Copper contamination in the soil created copper-tolerant plants. f - Natural selection favors copper tolerance in all soils near the old mine, not only in the contaminated soils. A,B,D
Based on the video and what you know about natural selection, which of the following must be true if evolution is the explanation for what the Grants have observed over time on Daphne? Select all that apply.
a - The beaks of individual birds can change depending on what food is available. b - Beak depth and length must be heritable. c - Beak depth and length must show variation among individuals of a single species. d - Over time, individuals can evolve to better fit the environment by changing heritable traits. e - Food must be plentiful for all birds. f - Beak depth and length must affect survival and/or reproduction of birds. B,C,F
Three of the most prominent definitions of species are the biological species concept, the phylogenetic species concept, and the morphological species (morphospecies) concept. Drag each characteristic to the appropriate bin based on the species concept(s) to which it applies.
biological: not applicable for extinct species morphological: relies on similarities in structure phylogenetic: based on evolutionary history morphological and phylogenetic: accommodates asexual reproduction species acceptance criteria can be subjective morphological, phylogenetic, and biological: used by scientists in classification
Which of the following are causes of evolutionary change?
genetic drift natural selection mutation gene flow
Based on this genetic information, which phylogenetic tree is most parsimonious? Select the most parsimonious tree. If there is a tie, select both trees. (For help approaching this problem, open Hint 2.)
phylogenetic tree III