InQuizitive Ch12

While living on the beach for the summer, a college student decides to make several personal changes. First, she goes to the tanning salon to get a good tan. She then visits a tattoo parlor to get a cute tattoo on her wrist. She also frequents a gym, toning her muscles. Lastly, she gets a perm, turning her hair curly. How many changes in allele frequency occurred in the student during this summer of change?

0 Allele frequencies do not change in an individual during its lifetime.

A new mutation occurs in the brain cells of one of the few remaining black rhinos in the wild. This mutation is unlikely to spread throughout the population.

False

Individuals evolve over their lifetime.

False

A hurricane blows a few individuals from a population of blackbirds onto a remote island. The subsequent population of blackbirds on the island displays lower genetic diversity than the original population.

Founder effect

Trees that grow faster and able to collect more sunlight are therefore able to produce more seeds, leaving behind more offspring. Snails with spots on their shells are better able to avoid predation are therefore able to survive longer, leaving behind more offspring.

Natural selection

The founder effect One or more of the few founders of the Amish population possessed the allele for polydactyly, and now it is more common in those populations.

The Amish populations in the United States began with relatively few individuals and have not recruited many newcomers to the population. Today, these Amish populations exhibit a much higher incidence of polydactyly (possessing extra digits) than other American populations. Which mechanism of evolution is likely responsible for this phenomenon?

Alleles can mutate within an individual.

True

Only mutations that occur in germ lines can be passed on to an offspring

True

Similar structures that evolved from a common ancestor are called homologous structures. On the other hand, similar structures that evolved completely independently of one another are called analogous structures and are produced by a process called convergent evolution. One example of this process is the similar anatomical features shared between a dolphin and a shark. It is important to consider traits that seem similar carefully so as to not confuse convergent evolution and common descent.

comparing and contrasting convergent evolution with evolution by common descent.

habitat where seeds have very tough shells

larger jaws in a mouse stronger beaks in a bird population

In cases of stabilizing selection, individuals with intermediate values of an inherited phenotypic trait have an advantage over other individuals in the population.

stabilizing selection

Individuals with intermediate values of an inherited phenotypic trait have an advantage over other individuals in the population.

stabilizing selection

Correct answer horizontal gene transfer gene flow exchange of genetic information in bacteria Incorrect answer evolution a genetic bottleneck

the evolution of vancomycin resistance in some populations of bacteria Select all of the correct descriptors of what is happening in this picture. https://ncia.wwnorton.com/media/57f7e5595e4ef6e50579a9d1/Inq_BN2_12.6-8_BIONOW2_IQ_12_12.jpg

https://ncia.wwnorton.com/media/57f7e5595e4ef6e50579a9d1/Inq_BN2_12.6-9_BIONOW2_IQ_12_12a.jpg https://ncia.wwnorton.com/media/57f7e5595e4ef6e50579a9d1/Inq_BN2_12.6-9_BIONOW2_IQ_12_12b.jpg https://ncia.wwnorton.com/media/57f7e5595e4ef6e50579a9d1/Inq_BN2_12.6-9_BIONOW2_IQ_12_12c.jpg https://ncia.wwnorton.com/media/57f7e5595e4ef6e50579a9d1/Inq_BN2_12.6-9_BIONOW2_IQ_12_12d.jpg One of these two bacteria has an extra loop of DNA, or plasmid, containing genetic information the other bacterium lacks. The formation of a conjugation tube connects the bacteria for horizontal gene transfer. A single strand of plasmid DNA from one bacterium is transferred to the other. The transferred DNA strand serves as a template for duplication so that both bacteria now have a full complement of the genetic material in the plasmid.

the evolution of vancomycin resistance in some populations of bacteria Place the steps of bacterial horizontal gene transfer in order from first to last by dragging them in sequence.

Gene flow Natural selection describes genetic changes that occur when some individuals reproduce much faster than the others. The founder effect describes genetic changes that take place when a few individuals establish a new population. In horizontal gene transfer, genes are moved from one group of bacteria to another, which is gene flow.

Genetic changes in populations that are brought about by horizontal gene transfer in bacteria are an example of what means of evolution?

warmer habitat

more active sweat glands in a horse

A larger, stronger jaw would suit a mouse for eating harder seeds

phenotype to the environment for which it is most suited

A drought causes a great reduction in a population of serval wildcats, leaving behind a population with lower genetic diversity.

Bottleneck effect

A toxic chemical spill in a forest kills most individuals of a population of beetles, leaving behind a population with lower genetic diversity.

Bottleneck effect

Which of the following are attributes of evolution?

Correct Answer results in genetic change occurs only in populations Incorrect Answer occurs only in animals occurs only over millions of years Evolution occurs in all types of organisms and species. Genetic changes must occur for evolution to happen. Evolution can occur on short or long time scales. Evolution can only occur in populations.

In the last half century, drier weather has decreased flower diversity in the Rocky Mountains, reducing the abundance of deep flowers. Thus, long-tongued bees, whose flowers have become scarce, have been outcompeted by short-tongued bees.

Directional

Directional selection is the most common pattern of natural selection, in which individuals at one extreme of an inherited phenotypic trait have an advantage over other individuals in the population.

Directional selection

Faster cheetahs are better able to catch fast prey. The faster the cheetahs become, the more food they are able to eat and the more offspring they are able to leave behind. In cases of directional selection, individuals at one extreme of an inherited phenotypic trait—like very high speed—have an advantage over individuals who fall short of that extreme—slower animals.

Directional selection

Individuals at one extreme of an inherited phenotypic trait have an advantage over other individuals in the population.

Directional selection

During one dry season, birds with large beaks survived on hard seeds and birds with small beaks survived on soft seeds, but birds with intermediate-sized beaks fed inefficiently on both types of seeds.

Disruptive

Disruptive selection occurs when individuals with either extreme of an inherited trait have an advantage over individuals with an intermediate phenotype.

Disruptive selection

habitat with many predators

More camouflaged color in a caterpillar. Duller color in a bird population.

Genetic drift This is an example of genetic drift because it describes a sudden reduction in the size of the population that resulted in random changes in spine-color allele frequencies

Most of the individuals in a cactus population have light colored spines, and a few have dark colored spines. After a fire breaks out in the area, killing many of the cacti, most of the remaining cacti display dark colored spines. This is an example of what mechanism of evolutionary change?

Male sheep with the biggest horns are able to drive away other males and are therefore able to mate more often, leaving behind more offspring.sexual selection. Colorful male guppies are more attractive to females and therefore are able to mate more often, leaving behind more offspring.

Sexual selection

False

Similar structures among organisms are always indicative of shared ancestry.

Mutations are random changes in DNA sequences that can lead to the generation of new alleles. Mutations are random changes in DNA sequences and are the only means by which new alleles are created.

Which of the following is the best description of a mutation and its role in evolution?

Some bacteria acquire new genes through a process called horizontal gene transfer. Staphylococcus and Enterococcus in proximity can swap genes. Some bacteria may carry extra loops of DNA called plasmids that carry genes for vancomycin resistance. These genes can be transferred through a conjugation tube. One strand is transferred to the recipient, which then uses that strand as a template to synthesize a second strand. In this way, both cells have the same resistance gene. If treated with the antibiotic, they will survive and pass on the gene to their offspring. This genetic change to a population of bacteria is an example of evolution.

describe evolution of vancomycin resistance Bacteria do not produce gametes. Evolution can take place after bacteria exchange genes through horizontal gene transfer. By passing one strand of DNA in a plasmid through a conjugation tube and using that strand as a template, the genes for antibiotic resistance can be shared and then reproduced.

In the last half century, drier weather has decreased flower diversity in the Rocky Mountains, reducing the abundance of deep flowers. Thus, long-tongued bees, whose flowers have become scarce, have been outcompeted by short-tongued bees.

directional

More active sweat glands cool the horse more readily, keeping it from overheating

phenotype to the environment for which it is most suited

Stronger beaks allow the birds to more easily crack the nut shells

phenotype to the environment for which it is most suited

The camouflaged colors allow the caterpillars to avoid detection from the birds

phenotype to the environment for which it is most suited

Limb of a monkey and limb of an octopus While the limb of a monkey and the tentacle of an octopus both serve a locomotive function, they evolved from completely different structures.

Analogous

Wing of a bird and wing of a butterfly While the wing of a bird and the wing of a butterfly both provide the same function—flight—they evolved from completely different structures.

Analogous

Different environments require different traits for organisms to remain successful. Natural selection removes from the population those traits that are not suited for their environment

Better camouflage would help individuals avoid predation.

Consider the following scenarios: 1) In mosquitoes, whether their bites can be felt by humans is a genetic trait of the mosquito. Over time, humans who feel mosquitoes biting swat and kill so many mosquitoes that most of the remaining mosquitoes possess bites that cannot be felt. 2) Orchid collectors search the rainforest for rare orchids. Some orchids have alleles that allow their roots to adhere to trees so strongly that they cannot be removed without killing the plant. The collectors leave these individuals alone and collect the others. After a while, most orchids remaining the forest display the strong adherence trait. 3) A person is given a medication to alleviate back pain. After a few months, the person must increase the dosage because the initial dose no longer has the same effect. 4) Your neighbor treats his yard with an herbicide to control weeds. None of the weeds are killed by the herbicide, but the weeds seem to show resistance to the herbicide after the treatment. Which scenario above is an example of evolution?

Correct Answer 1 & 2 Incorrect Answer 3 & 4 Since none of the weeds were killed during the treatment, no alleles were removed from the population. Therefore, no evolution has taken place. An individual person becoming habituated to a pain medication does not qualify as evolution. Orchids with alleles for weak adherence are removed from the population, changing the frequency of alleles. This is evolution. Mosquitoes with alleles for causing a sensation in their human hosts during bites are removed from the population, changing the frequency of alleles. This is evolution. For evolution to occur, there must be a change in allele frequency in a population.

Which of the following are possible outcomes of natural selection?

Correct Answer produce a population of redwood trees that grows faster produce a population of squirrels with darker fur coats produce a predatory bird population with more acute eyesight produce a faster population of deer When lighter fur coat alleles are removed from a population of squirrels, the resulting population will display darker coats on average. When slower growing redwood tree alleles are removed from the population, the resulting population will grow faster on average. When poor eyesight alleles are removed from a population of birds, the resulting population will have more acute eyesight on average. When slower deer alleles are removed from the population, the resulting population will be faster on average. Natural selection may result in any small change in characteristics—or larger, accrued changes over time.

Two populations of the same species of sea urchin, one with mostly long spines and the other with mostly short spines, are separated by an isthmus. A canal is built through the isthmus that connects the two urchin populations. Which of the following outcomes is likely to result after the new canal? https://ncia.wwnorton.com/media/57f7e5595e4ef6e50579a9d1/Inq_BN_12.6-7_FIG12.14_BIOLNOW1_CH11.jpg

Correct Answers The long-spine population will come to have more short-spine individuals. Incorrect Answers The spines of the long-spine population will become longer. Long-spine urchin individuals will be less frequent in the short-spine population. The canal opens up gene flow between the populations, which should make the allele frequencies in the two populations more similar.

This graph shows the color intensity of feathers for blue birds in the southern Appalachian Mountains in 1900 versus 2000. These fictional data provide an example of which type of selection? https://ncia.wwnorton.com/media/57f7e5595e4ef6e50579a9d1/Inq_BN2_12.2-5.jpg?nc=1573612241793

Disruptive Disruptive selection occurs when individuals with either extreme of an inherited trait have an advantage over individuals with an intermediate phenotype.

Individuals with either extreme of an inherited trait have an advantage over individuals with an intermediate phenotype.

Disruptive selection

Snails with dark shells are able to hide in dark forests. Snails with light shells are able to hide in the fields. Snails with dark and light stripes are not able to hide in either location.disruptive selection. In cases of disruptive selection, individuals at either extreme of an inherited phenotypic trait, like having a dark or light shell, have an advantage over the intermediate trait, in this case having a striped shell.

Disruptive selection

Correct Answer: mottled red dark gray blue gold Mutations are random and any plausible outcome in skin color is equally likely in this scenario. Mutations DO NOT arise to meet environmental challenges and could result in more, less, or unchanged adaptiveness to the new environment.

Due to pollution, a pond with a multi-colored bottom becomes a dark muted shade, making colorful fish easier for predators to see. A mutation occurs in the gene for skin color of a gold fish. Which of the following possible colors could arise from this mutation?

A population of birds displays different colors, each of which is associated with its own trait. Blue birds usually fly the fastest. Red birds usually sing the most types of songs. Green birds usually have the most offspring. Black birds usually have the best vision. Which color bird is most likely to be increasing in frequency in the population?

Green birds The types of birds that produce the most offspring are the ones that are most likely to be increasing in frequency.

Apples and oranges Apples and oranges both evolved from the same flowering plant structure.

Homologous

Flipper of a whale and wing of a bat Whale flippers and bat wings both evolved from the same vertebrate ancestor's forelimb.

Homologous

https://ncia.wwnorton.com/media/57f7e5595e4ef6e50579a9d1/Inq_BN2_12.2-2_beetles-green.jpg Disruptive selection https://ncia.wwnorton.com/media/57f7e5595e4ef6e50579a9d1/Inq_BN2_12.2-2_beetles-red.jpg Stabilizing selection https://ncia.wwnorton.com/media/57f7e5595e4ef6e50579a9d1/Inq_BN2_12.2-2_beetles-blue.jpg Directional selection

Imagine that you have collected individuals from three different species of beetle in your backyard. You measure the shell width of the beetles and compile data to create a graph for each species to show the number of beetles exhibiting each shell width. Based on your data, what pattern of natural selection is occurring in each beetle species?

Directional selection In this example of directional selection, evolution has shifted the bacterial phenotype toward one extreme.

In the chapter story, scientists explored evolution of populations of bacteria in hospitals. Bacteria such as Staphylococcus aureus evolved resistance to such antibiotics as methicillin and vancomycin when they were exposed to the selective pressure of those chemicals. The evolution of antibiotic resistance in the story represents one of three common patterns of natural selection.Match each pattern of selection with the description(s) that correctly exemplifies it. Bacterial populations in the chapter story became more resistant to antibiotics.

Stabilizing selection Intermediate-size hyena birth canals have a greater adaptive benefit than shorter or longer phenotypes, so the hyena population experiences stabilizing selection.

In the chapter story, scientists explored evolution of populations of bacteria in hospitals. Bacteria such as Staphylococcus aureus evolved resistance to such antibiotics as methicillin and vancomycin when they were exposed to the selective pressure of those chemicals. The evolution of antibiotic resistance in the story represents one of three common patterns of natural selection.Match each pattern of selection with the description(s) that correctly exemplifies it. Female hyenas with elongated birth canals have more mating opportunities than those with average-size birth canals; however, hyenas with really long birth canals tend to die during birth along with their pups.

Stabilizing selection In this example of stabilizing selection, the extreme phenotypes for human birth weight are less adaptive than the intermediate phenotypes. The phenotype selected for defines one of three natural selection patterns. In directional selection, one extreme phenotype has an advantage and is selected for. In disruptive selection, either extreme has an advantage over more intermediate phenotypes. In stabilizing selection, the intermediate phenotype has an advantage and is selected for.

In the chapter story, scientists explored evolution of populations of bacteria in hospitals. Bacteria such as Staphylococcus aureus evolved resistance to such antibiotics as methicillin and vancomycin when they were exposed to the selective pressure of those chemicals. The evolution of antibiotic resistance in the story represents one of three common patterns of natural selection.Match each pattern of selection with the description(s) that correctly exemplifies it. Human birth weights average approximately 8 pounds; babies weighing much more or much less than this average at birth generally have higher mortality rates.

Disruptive selection For toadfish undergoing disruptive selection, the extremely large and extremely small phenotypes have a reproductive advantage over intermediate phenotypes.

In the chapter story, scientists explored evolution of populations of bacteria in hospitals. Bacteria such as Staphylococcus aureus evolved resistance to such antibiotics as methicillin and vancomycin when they were exposed to the selective pressure of those chemicals. The evolution of antibiotic resistance in the story represents one of three common patterns of natural selection.Match each pattern of selection with the description(s) that correctly exemplifies it. Large male toadfish guard nests to attract females. Small male toadfish sneak mating opportunities.

Directional selection In this example of directional selection, rattlesnakes are more likely to survive in the presence of humans when they have extremely small rattles.

In the chapter story, scientists explored evolution of populations of bacteria in hospitals. Bacteria such as Staphylococcus aureus evolved resistance to such antibiotics as methicillin and vancomycin when they were exposed to the selective pressure of those chemicals. The evolution of antibiotic resistance in the story represents one of three common patterns of natural selection.Match each pattern of selection with the description(s) that correctly exemplifies it. Rattlesnakes in the western United States have reduced rattles on their tails and therefore draw less human attention.

Genetic Drift Bacterial populations are nearly wiped out by a lava flow; only the bacteria on the edge of the flow survive and reproduce. Founder events occur when a single or small group of individuals establishes an isolated population. Random events affect survival and reproduction. Natural selection Bacterial populations regularly exposed to antibiotics show increasing resistance to antibiotics. Nonrandom changes in allele frequency occur when beneficial genes are reproduced.

In this chapter, you read a story about how hospitals are finding that populations of bacteria such as Staphylococcus aureus are evolving resistance to more commonly used antibiotics such as methicillin, as well as to the antibiotics of "last resort," such as vancomycin. Natural selection is not the only mechanism for evolution. Genetic drift also can lead to evolution. Identify which examples below refer to genetic drift and which refer to natural selection. In both genetic drift and natural selection, the allele frequency changes in the population. In genetic drift, those changes are due to random events, but in natural selection, they are due to the nonrandom survival and reproduction of beneficial genes.

Correct answer Ovaries Testes Incorrect answer Heart Liver Breast tissue

In which of the following adult tissues could a mutation occur and be passed on to an offspring? Mutations that occur in the germ lines, such as those in the ovaries, can be passed on to offspring. Only mutations that occur in germ lines—not any other organ—can be passed on to offspring.

convergence: Tree-dwelling primates have prehensile tails for gripping branches. Tree-dwelling opossums also have prehensile tails. Primates and marsupials do not have a recent evolutionary ancestor. Their prehensile tails are a convergent trait due to tree-dwelling habits. Many birds and some kinds of bats that feed on plant nectar all have long flexible tongues. Two very different species of bird and a species of mammal have converged on a similar adaptation to make use of a similar food source. Common Descent: Hawaiian honeycreepers, with their elongated, nectar-sipping bills, all evolved from a finch-like ancestor. In this case, the wide, diverse group of honeycreepers all share an ancestor and share homologous traits expected in common descent. Primates use opposable thumbs to help climb. New World monkeys also have prehensile tails, but Old World monkeys do not. Monkeys that share a common ancestor may have different adaptations in different areas, while other traits reveal their common descent. Marsupial mammals throughout Australia show a wide diversity of forms that reflect the habitats in which they live. Marsupial mammals exhibit different adaptations in different habitats, but because they all share an ancestor, they retain evidence (including their reproductive pouch) of common descent.

Natural selection can, through common descent, produce closely related species that have similarities due to their shared ancestry. Natural selection can also, through convergent evolution, lead to distantly related species appearing very similar. Identify which examples reflect common descent and which reflect convergence.

Convergent evolution, in which similar structures evolve independently, seems to have taken place countless times. For example, many different lineages of aquatic organisms evolved limbs with paddle-like flippers instead of independent digits (e.g., dolphins, seals, ducks, manatees, etc.). If these structures didn't evolve from a common ancestor, what is a good explanation for their similarity?

Paddle-like limbs are more efficient at moving organisms through water than independent digits. Many times, convergent evolution independently leads to similar traits because the different organisms are facing similar challenges, such as moving through water.

The figure below displays the relationships among three populations of mountain ants (1, 2, and 3). The size of each circle represents the relative size of the population, and the size of each arrow represents the relative rate of gene flow between two populations. Based on this figure, which of the following statements about the genetic relationships among these three populations is most likely true? https://ncia.wwnorton.com/media/57f7e5595e4ef6e50579a9d1/Inq_BN_12.6-1_BIOLNOW1_CH11.jpg?nc=1573612288444

Population 1 & 3 should be more genetically related to each other than either is to population 2. The figure indicates that more ants are travelling between populations 1 and 3 than between any other pair of populations. Therefore, those two populations should be the most genetically related.

True

Similar structures among organisms can sometimes arise independently via convergent evolution.

Place the following events in the order they must occur for natural selection to lead to evolution

Some individuals in a shrub population possess spines near their leaves. Shrubs without thorns are more frequently eaten by rabbits. Most shrubs in the resulting population now possess thorns. Since the thorn-bearing plants survive to reproduce more, their genes (and phenotypes) become more prominent.

Short plants are outcompeted for sunlight, while extremely tall plants are more susceptible to wind damage; thus, more plants of medium height survive.

Stabilizing

Birds that lay too few eggs do not leave behind many offspring. Birds that lay too many eggs are often unable to care for them. Therefore, most birds lay an intermediate number of eggs. In cases of stabilizing selection, individuals with intermediate values of an inherited phenotypic trait, like producing an intermediate number of eggs, have an advantage over both extremes, like very high and very low numbers of eggs.

Stabilizing selection

Many hospitals are facing the challenge of battling methicillin-resistant Staphylococcus aureus (MRSA). The populations of these bacteria found in the treatment and operating rooms of a single hospital may be the descendants of the first bacteria in the hospital to develop resistance to the antibiotic methicillin. This common descent means closely related groups have the same homologous traits because they have the same ancestor. Meanwhile, the evolution of vancomycin-resistant Staphylococcus aureus (VRSA) has been documented 14 times in unrelated populations. The appearance of similar analogous traits in genetically distinct populations is convergent evolution.

This chapter in the textbook includes a story about how hospitals are finding that populations of bacteria such as Staphylococcus aureus are evolving resistance to more commonly used antibiotics such as methicillin, as well as to the antibiotics of "last resort," such as vancomycin. Drag the terms to correctly complete the passage.

Correct Answer: Bacteria that happen to have mutations for antibiotic resistance are more likely to survive and reproduce. Bacteria acquire antibiotic resistance through gene flow; the antibiotic-resistance gene then increases in a population as the bacteria survive and reproduce. Incorrect Answer: Antibiotics stimulate mutations that cause resistance in bacteria. If antibiotics are used, then bacteria will certainly evolve resistance to them. Evolution of antibiotic resistance can happen in even a single bacterium.

This chapter of the textbook includes a story about how hospitals are finding that populations of bacteria such as Staphylococcus aureus are evolving resistance to more commonly used antibiotics such as methicillin, as well as to the antibiotics of "last resort," such as vancomycin. Which of the statements below are correct about how bacteria evolve antibiotic resistance?

Correct answer A palm tree evolves a single trunk with branches and leaves only on the top from grass-like ancestors and a cycad tree evolves a single trunk with branches and leaves only on the top from cone-bearing ancestors. This is an example of convergent evolution because the similar traits of palm trees and cycad trees evolved independently from separate ancestors. A snake evolves a long, slender, and legless body from lizard-shaped ancestors; and an eel evolves a long, slender, legless body from regular fish-shaped ancestors. This is an example of convergent evolution because the similar traits of snakes and eels evolved independently from separate ancestors. Incorrect answer A lizard and a salamander both evolve a long, slender body with four limbs from the same four-limbed vertebrate ancestor. This is not an example of convergent evolution because the similar traits of lizards and salamanders evolved from a common ancestor. Flamingos and ducks evolved two hind limbs for walking and two forelimbs for flying from a common ancestor with these traits. This is not an example of convergent evolution because the similar traits of flamingos and ducks evolved from a common ancestor.

Which of the following are examples of convergent evolution?

Correct answer: mutation Random changes in DNA sequences can lead to new alleles. Mutation is likely the only means by which new alleles are generated. Incorrect answer: gene flow Gene flow is only a mechanism by which pre-existing alleles are transferred among populations. natural selction Natural selection operates by changing the relative frequency of pre-existing alleles in the population, most often by eliminating traits—not creating them. genetic bottleneck A genetic bottleneck reduces the genetic variation in a population.

Which of the following mechanisms generates new alleles?

Correct answer: A city development bisects a swamp, which divides the land into two separate swamps. Isolating portions of the swamp from one another decreases gene flow between populations in those portions, which should result in increased genetic diversity among them. A dam is built, which keeps water from flowing in upstream portions of a stream. Isolating portions of the stream from one another decreases gene flow between populations in those portions, which should result in increased genetic diversity among them. Incorrect answer: The temperature of a bay warms by two degrees. Warming of a bay may cause changes in its populations, but it is not likely increase the genetic variation. Rainfall increases and water levels rise, connecting previously isolated lakes. Connecting previously unconnected streams to one another increases gene flow between two populations, which should result in an overall decrease in genetic diversity in the newly joined population.

Which of the following scenarios should lead to two populations becoming more different from each other?

Ten frogs live in a pond in your backyard, five are homozygous for an allele that results in dark skin, and five are homozygous for an allele that results in lighter skin. A drought occurs, killing three frogs with light skin alleles. The rest of the population breeds and produces the next generation of frogs. Did the frog population evolve?

Yes. The allele frequencies of light to dark alleles were 1:1 before the drought. After the drought the frequency of light to dark skin alleles became 3:5.