What are adaptations?

A) geologic changes over time

B) rocks containing fossils

C) inherited characteristics of organisms that enhance their survival

D) descent with modification from a common ancestor

C) inherited characteristics of organisms that enhance their survival

Which of these conditions are always true of populations evolving due to natural selection?

Condition 1: The population must vary in traits that are heritable.

Condition 2: Some heritable traits must increase reproductive success.

Condition 3: Individuals pass on most traits that they acquire during their lifetime.

A) Condition 1 only

B) Condition 2 only

C) Conditions 1 and 2

D) Conditions 2 and 3

C) Conditions 1 and 2

A farmer uses triazine herbicide to control pigweed in his field. For the first few years, the triazine works well and almost all the pigweed dies; but after several years, the farmer sees more and more pigweed. Which of these statements explains why the pigweed reappeared?

A) The herbicide company lost its triazine formula and started selling poor-quality triazine.

B) Natural selection caused the pigweed to mutate, creating a new triazine-resistant species.

C) Triazine-resistant pigweed has less-efficient photosynthesis metabolism.

D) Triazine-resistant weeds were more likely to survive and reproduce.

D) Triazine-resistant weeds were more likely to survive and reproduce.

Which one of the following statements best defines artificial selection?

A) Process that occurs when individuals inherit traits that enable them to survive and reproduce

B) Process where humans decide which plants and/or animals will not breed

C) Process of human directed breeding aimed to produce selective traits in selected species

D) Process that favors beneficial mutations

C) Process of human directed breeding aimed to produce selective traits in selected species

After the drought of 1977, researchers hypothesized that on the Galápagos Island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of these events is now most likely to occur to finch beaks on this island?

A) evolution of yet larger, deeper beaks over time, until all birds have relatively large, deep beaks

B) evolution of smaller, pointier beaks over time, until all birds have relatively small, pointy beaks

C) increased variation in beak size and shape over time

D) no change in beak size and shape over time

C) increased variation in beak size and shape over time

The following question is based on information from Frank M. Frey, "Opposing Natural Selection from Herbivores and Pathogens May Maintain Floral-Color Variation in Claytonia virginica (Portulacaceae)," Evolution 58(11), 2004: 2426-37.

Claytonia virginica is a woodland spring herb with flowers that vary from white, to pale pink, to bright pink. Slugs prefer to eat pink-flowering over white-flowering plants (due to chemical differences between the two), and plants experiencing severe herbivory are more likely to die. The bees that pollinate this plant also prefer pink to white flowers, so that Claytonia with pink flowers have greater relative fruit set than Claytonia with white flowers. A researcher observes that the percentage of different flower colors remains stable in the study population from year to year. Given no other information, if the researcher removes all slugs from the study population, what do you expect to happen to the distribution of flower colors in the population over time?

A) The percentage of pink flowers should increase over time.

B) The percentage of white flowers should increase over time.

C) The distribution of flower colors should not change.

D) The distribution of flower colors should randomly fluctuate over time.

A) The percentage of pink flowers should increase over time.

Which statement illustrates the connection between natural selection and overreproduction of a population?

A) Populations vary in their inherited traits.

B) Species produce more offspring than can survive in the environment.

C) Individuals with inherited traits that promote survival tend to have more surviving offspring.

D) Individuals with traits that do not enhance survival cannot reproduce.

C) Individuals with inherited traits that promote survival tend to have more surviving offspring.

Darwin used the phrase "descent with modification" to explain ________.

A) unity of life

B) descent of all organisms from a single, ancient ancestor

C) that habitat differences stimulate change in organisms

D) evolution of the unity and diversity of life

D) evolution of the unity and diversity of life

Which of the following statements describe evolution?

A) Individuals evolve in response to their environment.

B) The match between organism and their environment decreases.

C) Natural selection chooses the most popular trait.

D) Quick changes occur in an individual's phenotype.

A) Individuals evolve in response to their environment.

Given a population that contains genetic variation, what is the correct sequence of the following events under the influence of natural selection?

1. Well-adapted individuals leave more offspring than do poorly adapted individuals.
2. A change occurs in the environment.
3. Genetic frequencies within the population change.
4. Poorly adapted individuals have decreased survivorship.

A) 2 → 4 → 1 → 3

B) 4 → 2 → 1 → 3

C) 4 → 2 → 3 → 1

D) 2 → 4 → 3 → 1

A) 2 → 4 → 1 → 3

Which of the following factors could cause a surge in population size?

A) a decrease in available food

B) an increase in the number of predators

C) better eyesight evolves in the population

D) decreased camouflage evolves in the population

C) better eyesight evolves in the population

Which of the following statements describe the effect of evolution on a population?

A) increasingly better match between a population and its environment

B) increased genetic variation among individuals in a population

C) increased variation among individuals in a population

D) increased sexual reproduction in a population

A) increasingly better match between a population and its environment

Which of Darwin's ideas had the strongest connection to his reading of Malthus's essay on human population growth?

A) descent with modification

B) variation among individuals in a population

C) struggle for existence

D) that the ancestors of the Galápagos finches had come from the South American mainland

C) struggle for existence

If Darwin had been aware of genes and their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement?

A) If natural selection can change gene frequency in a population over generations, given enough time and genetic diversity, then natural selection can cause sufficient genetic change to produce new species from old ones.

B) If an organism's somatic cell genes change during its lifetime, making it more fit, then it will be able to pass these genes on to its offspring.

C) If an organism acquires new genes by engulfing, or being infected by, another organism, then a new genetic species will result.

D) A single mutation in a single gene in a single gamete, if inherited by future generations, will produce a new species.

A) If natural selection can change gene frequency in a population over generations, given enough time and genetic diversity, then natural selection can cause sufficient genetic change to produce new species from old ones.

Which one of the following observations did Darwin first make during his discovery of evolution?

A) The ability of individuals to survive and reproduce is not equal.

B) There is variation in inherited traits.

C) Individuals who reproduce more leave more offspring.

D) The unequal ability to reproduce leads to the accumulation of favorable traits in a population.

B) There is variation in inherited traits.

Currently, two extant elephant species (X and Y) are classified in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true?

A) Species X and Y are not related to species Z.

B) Species X and Y share a greater number of homologies with each other than either does with species Z.

C) Species X and Y share a common ancestor that is alive today.

D) Species X and Y are the result of artificial selection.

B) Species X and Y share a greater number of homologies with each other than either does with species Z.

In a hypothetical environment, fishes called pike-cichlids are visual predators of large, adult algae-eating fish (in other words, they locate their prey by sight). The population of algae-eaters experiences predatory pressure from pike-cichlids. Which of the following is least likely to result in the algae-eater population in future generations?

A) selection for drab coloration of the algae-eaters

B) selection for nocturnal algae-eaters (active only at night)

C) selection for larger female algae-eaters, bearing broods composed of more, and larger, young

D) selection for algae-eaters that become sexually mature at smaller overall body sizes

C) selection for larger female algae-eaters, bearing broods composed of more, and larger, young

Currently, two of the living elephant species (X and Y) are placed in the genus Loxodonta, and a third surviving species (Z) is placed in the genus Elephas. Assuming this classification reflects evolutionary relatedness, which of the following is the most accurate phylogenetic tree?

Cotton-topped tamarins are small primates with tufts of long white hair on their heads. While studying these creatures, you notice that males with longer hair get more opportunities to mate and father more offspring. To test the hypothesis that having longer hair is adaptive in these males, you should ________.

A) test whether other traits in these males are also adaptive

B) look for evidence of hair in ancestors of tamarins

C) determine if hair length is heritable

D) test whether males with shaved heads are still able to mate

C) determine if hair length is heritable

Which of the following is the best modern definition of evolution?

A) descent with modification

B) change in the number of genes in a population over time

C) survival of the fittest

D) inheritance of acquired characters

A) descent with modification

Microevolutions occur when ________.

A) a bird has a beak of a particular size that does not grow larger during a drought

B) changes in allele frequencies in a population occur over generations

C) gene flow evenly transfers alleles between populations

D) individuals within all species vary in their phenotypic traits

B) changes in allele frequencies in a population occur over generations

Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true?

A) Each bird evolved a deeper, stronger beak as the drought persisted.

B) Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted.

C) Each bird that survived the drought produced only offspring with deeper, stronger beaks than seen in the previous generation.

D) The frequency of the strong-beak alleles increased in each bird as the drought persisted.

B) Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted.

Which statement about variation is true?

A) All phenotypic variation is the result of genotypic variation.

B) All genetic variation produces phenotypic variation.

C) All nucleotide variability results in neutral variation.

D) All new alleles are the result of nucleotide variability.

D) All new alleles are the result of nucleotide variability.

Which of the following descriptions illustrates phenotype variation caused by environment?

A) inheritance of body builder "physique"

B) diet of caterpillars changes their morphology

C) variation in horse coat color

D) average beak depth during drought

B) diet of caterpillars changes their morphology

Genetic variation ________.

A) is created by the direct action of natural selection

B) arises in response to changes in the environment

C) must be present in a population before natural selection can act upon the population

D) tends to be reduced when diploid organisms produce gametes

C) must be present in a population before natural selection can act upon the population

HIV's genome of RNA includes the code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for antiretroviral drugs. Drugs called nucleoside analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR.

Which of the following treatment options would most likely avoid the evolution of drug-resistant HIV (assuming no drug interactions or side effects)?

A) Use a series of NAs, one at a time, and change about once a week.

B) Use a single PI, but slowly increase the dosage over the course of a week.

C) Use high doses of NA and a PI at the same time for a period not to exceed one day.

D) Use moderate doses of NA and two different PIs at the same time for several months.

D) Use moderate doses of NA and two different PIs at the same time for several months.

HIV's genome of RNA includes the code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for antiretroviral drugs. Drugs called nucleoside analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR.

Which mechanism produces variation for evolution by shuffling existing alleles?

A) rapid reproduction

B) sexual reproduction

C) mutation

D) changes in chromosome numbers

B) sexual reproduction

A researcher discovered a species of moth that lays its eggs on oak trees. Eggs are laid at two distinct times of the year: early in spring when the oak trees are flowering and in midsummer when flowering is past. Caterpillars from eggs that hatch in spring feed on oak flowers and look like oak flowers. But caterpillars that hatch in summer feed on oak leaves and look like oak twigs.

How does the same population of moths produce such different-looking caterpillars on the same trees? To answer this question, the biologist caught many female moths from the same population and collected their eggs. He put at least one egg from each female into eight identical cups. The eggs hatched, and at least two larvae from each female were maintained in one of the four temperature and light conditions listed below.

In each of the four environments, one of the caterpillars was fed oak flowers, the other oak leaves. Thus, there were a total of eight treatment groups (4 environments × 2 diets).

Which of the following is a testable hypothesis that would explain the differences in caterpillar appearance observed in this population?

A) The longer day lengths of summer trigger the development of twig-like caterpillars.

B) Winter causes ugly caterpillar and trees.

C) Differences in air pressure, due to differences in elevation, trigger the development of different types of caterpillars.

D) Differences in diet trigger the development of different types of caterpillars.

D) Differences in diet trigger the development of different types of caterpillars.

Genetic drift produces variation for evolution when ________.

A) a gene pool decreases because a smaller group establishes a new population

B) chance events cause allele frequencies to fluctuate unpredictably

C) sudden change in environment drastically reduces the gene pool

D) a population has heritable traits better suited to the environment

B) chance events cause allele frequencies to fluctuate unpredictably

Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years. If 9 in 10,000 newborn babies have the disease, what are the expected frequencies of the dominant (A1) and recessive (A2) alleles according to the Hardy-Weinberg equation?

A) f(A1) = 0.9997, f(A2) = 0.0003

B) f(A1) = 0.9800, f(A2) = 0.0200

C) f(A1) = 0.9700, f(A2) = 0.0300

D) f(A1) = 0.9604, f(A2) = 0.0392

C) f(A1) = 0.9700, f(A2) = 0.0300

Suppose 64% of a remote mountain village can taste phenylthiocarbamide (PTC) and must, therefore, have at least one copy of the dominant PTC taster allele. If this population conforms to Hardy-Weinberg equilibrium for this gene, what percentage of the population must be heterozygous for this trait?

A) 16%

B) 32%

C) 40%

D) 48%

D) 48%

If individuals tend to mate within a subset of the population, there is ________.

A) no selection

B) no genetic drift

C) no gene flow

D) random mating

D) random mating

Which Hardy-Weinberg condition is affected by population size?

A) selection

B) genetic drift

C) gene flow

D) no mutation

B) genetic drift

Researchers studying a small milkweed population note that some plants produce a toxin and other plants do not. They identify the gene responsible for toxin production. The dominant allele (T) codes for an enzyme that makes the toxin, and the recessive allele (t) codes for a nonfunctional enzyme that cannot produce the toxin. Heterozygotes produce an intermediate amount of toxin. The genotypes of all individuals in the population are determined (see chart) and used to determine the actual allele frequencies in the population.

Is this population in Hardy-Weinberg equilibrium?

A) Yes.

B) No; there are more heterozygotes than expected.

C) No; there are more homozygotes than expected.

D) More information is needed to answer this question.

C) No; there are more homozygotes than expected.

Which one of the following conditions would allow gene frequencies to change by chance?

A) large population

B) small populations

C) mutation

D) gene flow

B) small populations

The higher the proportion of loci that are "fixed" in a population, the lower are that population's ________.

A) nucleotide variability

B) chromosome number

C) average heterozygosity

D) nucleotide variability and average heterozygosity

D) nucleotide variability and average heterozygosity

Whenever diploid populations are in Hardy-Weinberg equilibrium at a particular locus, ________.

A) the allele's frequency should not change from one generation to the next

B) natural selection, gene flow, and genetic drift are acting equally to change an allele's frequency

C) two alleles are present in equal proportions

D) individuals within the population are evolving

A) the allele's frequency should not change from one generation to the next

In the formula for determining a population's genotype frequencies, the "2" in the term 2pq is necessary because ________.

A) the population is diploid

B) heterozygotes can come about in two ways

C) the population is doubling in number

D) heterozygotes have two alleles

B) heterozygotes can come about in two ways

In the formula for determining a population's genotype frequencies, the "pq" in the term 2pq is necessary because ________.

A) the population is diploid

B) heterozygotes can come about in two ways

C) the population is doubling in number

D) heterozygotes have two alleles

D) heterozygotes have two alleles

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.3. What is the frequency of individuals that are homozygous for this allele?

A) 0.09

B) 0.49

C) 0.9

D) 9.0

A) 0.09

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.2. What is the frequency of individuals that are heterozygous for this allele?

A) 0.020

B) 0.04

C) 0.16

D) 0.32

D) 0.32

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.1. What is the frequency of individuals with AA genotype?

A) 0.20

B) 0.32

C) 0.42

D) 0.81

D) 0.81

You sample a population of butterflies and find that 56% are heterozygous at a particular locus. What should be the frequency of the homozygous individuals in this population?

A) 0.08

B) 0.09

C) 0.70

D) 0.50

D) 0.50

In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?

A) 0.36

B) 0.64

C) 0.75

D) 0.80

D) 0.80

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants.

What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait (aa) has not changed over time?

A) The two phenotypes are about equally adaptive under laboratory conditions.

B) The genotype AA is lethal.

C) There has been a high rate of mutation of allele A to allele a.

D) There has been sexual selection favoring allele a.

A) The two phenotypes are about equally adaptive under laboratory conditions.

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants.

What is the estimated frequency of allele A in the gene pool?

A) 0.25

B) 0.50

C) 0.75

D) 0.125

B) 0.50

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants.

What proportion of the population is probably heterozygous (Aa) for this trait?

A) 0.05

B) 0.25

C) 0.50

D) 0.75

C) 0.50

Which one of these processes describes bottleneck effect?

A) chance events that change allele frequency

B) alleles transferred to the next generation in portions that differ from previous generation

C) transfer of alleles in and out of a population due to movement of fertile individuals

D) sudden change in environments that alters gene frequency of a population

D) sudden change in environments that alters gene frequency of a population

Comparisons of Neanderthal DNA revealed that there are more similarities to non-African DNA than reference sequences from West Africans. Additionally, scientists found that Neanderthal DNA is as closely related to East Asians as to Europeans. This indicates that interbreeding occurred before human migration further east. What process of population genetics generated these results?

A) adaptive evolution

B) gene flow

C) gene drift

D) nonrandom mating

B) gene flow

Soon after the island of Hawaii rose above the sea surface (somewhat less than one million years ago), the evolution of life on this new island should have been most strongly influenced by ________.

A) a genetic bottleneck

B) sexual selection

C) habitat differentiation

D) the founder effect

D) the founder effect

In 1983, a population of dark-eyed junco birds became established on the campus of the University of California, San Diego (UCSD), which is located many miles from the junco's normal habitat in the mixed-coniferous temperate forests in the mountains. Juncos have white outer tail feathers that the males display during aggressive interactions and during courtship displays. Males with more white in their tail are more likely to win aggressive interactions, and females prefer to mate with males with more white in their tails. Females have less white in their tails than do males, and display it less often. (Pamela J. Yeh. 2004. Rapid evolution of a sexually selected trait following population establishment in a novel habitat. Evolution 58[1]:166-74.)

The UCSD campus male junco population tails were, on average, 36% white, whereas the tails of males from nearby mountain populations averaged 40-45% white. If this observed trait difference were due to a difference in the original colonizing population, it would most likely be due to ________.

A) mutations in the UCSD population

B) gene flow between populations

C) a genetic bottleneck

D) a founder effect

D) a founder effect

The Dunkers are a religious group that moved from Germany to Pennsylvania in the mid-1700s. They do not marry with members outside their own immediate community. Today, the Dunkers are genetically unique and differ in gene frequencies, at many loci, from all other populations including those in their original homeland. Which of the following mechanisms likely explains the genetic uniqueness of this population?

A) population bottleneck and Hardy-Weinberg equilibrium

B) heterozygote advantage and stabilizing selection

C) mutation and natural selection

D) founder effect and genetic drift

D) founder effect and genetic drift

An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population happens to have broader stripes, on average, than the initial population. If broadness of stripes is genetically determined, what effect has the ground-squirrel population experienced during the earthquake?

A) directional selection

B) disruptive selection

C) a founder event

D) a genetic bottleneck

D) a genetic bottleneck

Which of the following is the most predictable outcome of increased gene flow between two populations?

A) lower average fitness in both populations

B) higher average fitness in both populations

C) increased genetic difference between the two populations

D) decreased genetic difference between the two populations

D) decreased genetic difference between the two populations

In 1986, a nuclear power accident in Chernobyl, USSR (now Ukraine), led to high radiation levels for miles surrounding the plant. The high levels of radiation caused elevated mutation rates in the surviving organisms, and evolutionary biologists have been studying rodent populations in the Chernobyl area ever since. Based on your understanding of evolutionary mechanisms, which of the following most likely occurred in the rodent populations following the accident?

A) Mutations caused major changes in rodent physiology over time.

B) Mutation led to increased genetic variation.

C) Mutation caused genetic drift and decreased fitness.

D) Mutation caused the fixation of new alleles.

B) Mutation led to increased genetic variation.

Over time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing ________.

A) nonrandom mating

B) geographic isolation

C) genetic drift

D) gene flow

D) gene flow

You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice that the viability of the flies has decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to ________.

A) cross your flies with flies from another lab

B) reduce the number of flies that you transfer at each generation

C) transfer only the largest flies

D) change the temperature at which you rear the flies

A) cross your flies with flies from another lab

Two populations of birds with somewhat different coloration live on opposite sides of a peninsula. The habitat between the populations is not suitable for these birds. When birds from the two populations are brought together, they produce young whose appearance is intermediate between the two parents. These offspring will breed with each other or with birds from either parent population, and all offspring of these pairings appear intermediate to various degrees.

What keeps the two populations separate?

A) temporal reproductive isolation

B) lack of hybrid viability

C) behavior isolates reproductive activities

D) habitat isolation

D) habitat isolation

If biological species are defined in terms of reproductive compatibility, the formation of a new species hinges on ________.

A) gene flow

B) reproductive isolation

C) hybrid formation

D) gene pool expansion

B) reproductive isolation

Which of the following statements describes mechanical isolation prezygotic barrier?

A) two species live in different habitats

B) two species mate at different times

C) two species share courtship activities

D) two snails have shells that spiral in different directions

A) two species live in different habitats

Three populations of crickets look very similar, but the males have courtship songs that sound different. What function would this difference in song likely serve if the populations came in contact?

A) a temporal reproductive isolating mechanism

B) a postzygotic isolating mechanism

C) a behavioral reproductive isolating mechanism

D) a gametic reproductive isolating mechanism

C) a behavioral reproductive isolating mechanism

Many songbirds breed in North America in the spring and summer, and then migrate to Central and South America in the fall. They spend the winter in these warmer areas where they feed and prepare for the spring migration north and another breeding season. Two hypothetical species of sparrow, A and B, overwinter together in mixed flocks in Costa Rica. In spring, species A goes to the east coast of North America, and species B goes to the west coast. What can you say about the isolating mechanisms of these two species?

A) They must have strong postzygotic isolating mechanisms to spend winter in such close proximity.

B) They must have strong prezygotic isolating mechanisms to spend winter in such close proximity.

C) These two species mate in different climates.

D) Reinforcement must be occurring when they winter together.

C) These two species mate in different climates.

The peppered moth provides a well-known example of natural selection. The light-colored form of the moth was predominant in England before the Industrial Revolution. In the mid-19th century, a dark-colored form appeared. The difference is produced by a dominant allele of one gene. By about 1900, approximately 90% of the moths around industrial areas were dark colored, whereas light-colored moths were still abundant elsewhere. Apparently, birds could readily find the light moths against the soot-darkened background in industrial areas and, therefore, were eating more light moths. Recently, use of cleaner fuels has greatly reduced soot in the landscape, and the dark-colored moths have been disappearing. Should the two forms of moths be considered separate species?

A) Yes; natural selection has affected the frequency of the two different forms.

B) Yes; they have completely different coloration.

C) Yes; they are reproductively isolated based on habitat.

D) No; they still can interbreed.

D) No; they still can interbreed.

Which statement describes unity within a species?

A) A species can be distinguished by body shape and other structural features.

B) Members have the potential to interbreed in nature and produce viable, fertile offspring.

C) A species is described in terms of its interaction with living and non-living environment.

D) The DNA sequence lacks similarities.

B) Members have the potential to interbreed in nature and produce viable, fertile offspring.

The common edible frog of Europe is a hybrid between two species, Rana lessonae and Rana ridibunda. The hybrids were first described in 1758 and have a wide distribution, from France across central Europe to Russia. Both male and female hybrids exist, but when they mate among themselves, they are rarely successful in producing offspring. What can you infer from this information?

A) Postzygotic isolation exists between the two frog species.

B) Prezygotic isolation exists between the two frog species.

C) These two species are likely in the process of fusing back into one species.

D) The hybrids form a separate species under the biological species concept.

A) Postzygotic isolation exists between the two frog species.

Macroevolution is ________.

A) the same as microevolution, but includes the origin of new species

B) evolution above the species level

C) defined as the evolution of microscopic organisms into organisms that can be seen with the naked eye

D) defined as a change in allele or gene frequency over the course of many generations

B) evolution above the species level

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

A) genetic

B) ecological

C) biological

D) morphological

C) biological

There is still some controversy among biologists about whether Neanderthals should be placed within the same species as modern humans or into a separate species of their own. Most DNA sequence data analyzed so far indicate that there was probably little or no gene flow between Neanderthals and Homo sapiens. Which species concept describing species relationship between modern humans and Neanderthals is most applicable in these observations?

A) genetic

B) ecological

C) morphological

D) biological

D) biological

You are confronted with a box of preserved grasshoppers of various species that are new to science and have not been described. Your assignment is to separate them into species. There is no accompanying information as to where or when they were collected. Which species concept will you have to use?

A) biological

B) genetic

C) ecological

D) morphological

D) morphological

Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile. This kind of isolation is most similar to which of the following reproductive isolating mechanisms?

A) temporal isolation

B) behavioral isolation

C) habitat isolation

D) gametic isolation

C) habitat isolation

Rank the following in order from most general to most specific.

1. gametic isolation
2. reproductive isolating mechanism
3. sperm-egg incompatibility in sea urchins
4. prezygotic isolating mechanism

A) 2, 3, 1, 4

B) 2, 4, 1, 3

C) 4, 1, 2, 3

D) 4, 2, 1, 3

B) 2, 4, 1, 3

Two species of frogs belonging to the same genus occasionally mate, but the embryos stop developing after a day and then die. These two frog species separate by ________.

A) reduced hybrid viability

B) hybrid breakdown

C) reduced hybrid fertility

D) gametic isolation

A) reduced hybrid viability

The production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) is an example of ________.

A) reduced hybrid viability

B) hybrid breakdown

C) reduced hybrid fertility

D) mechanical isolation

C) reduced hybrid fertility

Which postzygotic barriers prevent formation of hybrids beyond the first generations?

A) increased hybrid vulnerability

B) increased hybrid fertility

C) hybrid breakdown

D) hybrid gamete isolation

C) hybrid breakdown

Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. Pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species. These two juniper species are kept separate by ________.

A) habitat isolation

B) temporal isolation

C) gametic isolation

D) behavioral isolation

C) gametic isolation

What does the biological species concept use as the primary criterion for determining species boundaries?

A) geographic isolation

B) niche differences

C) gene flow

D) morphological similarity

C) gene flow

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

A) a population

B) a species

C) the entire range of a genus

D) the hybrid zone

B) a species

About 3 million years ago, the Isthmus of Panama (a narrow strip of land connecting North and South America) formed, dividing marine organisms into Pacific and Caribbean populations. Researchers have examined species of snapping shrimp on both sides of the isthmus. Based on the morphological species concept, there appeared to be seven pairs of species, with one species of each pair in the Pacific and the other in the Caribbean. The different species pairs live at somewhat different depths in the ocean. Using mitochondrial DNA sequences, the researchers estimated phylogenies and found that each of these species pairs, separated by the isthmus, were indeed each other's closest relatives. The researchers investigated mating in the lab and found that many species pairs were not very interested in courting with each other, and any that did mate almost never produced fertile offspring. (Reference: Y. Kondo and A. Kashiwagi. 2004. Experimentally induced autotetraploidy and allotetraploidy in two Japanese pond frogs. Journal of Herpetology 38(3):381-92.)

If the isthmus formed gradually rather than suddenly, what pattern of genetic divergence would you expect to find in these species pairs?

A) similar percentages of difference in DNA sequence between all pairs of sister species

B) greater percentage of difference in DNA sequence between species that inhabit deep water than between species that inhabit shallow water

C) greater percentage of difference in DNA sequence between species that inhabit shallow water than between species that inhabit deep water

D) smaller percentage of difference DNA sequence between species that inhabit than between shallow water

B) greater percentage of difference in DNA sequence between species that inhabit deep water than between species that inhabit shallow water

Which of the following describes the most likely order of events in allopatric speciation?

A) genetic drift, genetic isolation, divergence

B) genetic isolation, divergence, genetic drift

C) divergence, genetic drift, genetic isolation

D) genetic isolation, genetic drift, divergence

D) genetic isolation, genetic drift, divergence

You want to study divergence of populations, and you need to maximize the rate of divergence to see results within the period of your grant funding. You will form a new population by taking some individuals from a source population and isolating them so the two populations cannot interbreed. What combination of characteristics would maximize your chance of seeing divergence in this study?

1. Choose a random sample of individuals to form the new population.
2. Choose individuals from one extreme to form the new population.
3. Choose a species to study that produces many offspring.
4. Choose a species to study that produces a few, large offspring.
5. Place the new population in the same type of environment as the source population.
6. Place the new population in a novel environment compared to that of the source population.

A) 1, 3, and 6

B) 1, 4, and 6

C) 2, 3, and 5

D) 2, 3, and 6

D) 2, 3, and 6

Which of these animals could overcome the geographic barrier of water that causes allopatric speciation?

A) birds

B) pollen

C) small rodents

D) mountain lions

D) mountain lions

How are two different species most likely to evolve from one ancestral species?

A) sympatrically, by a point mutation affecting morphology or behavior

B) sympatrically, due to extensive inbreeding

C) allopatrically, due to extensive inbreeding

D) allopatrically, after the ancestral species has split into two populations

D) allopatrically, after the ancestral species has split into two populations

House finches were found only in western North America until 1939, when a few individuals were released in New York City. These individuals established a breeding population and gradually expanded their range. The western population also expanded its range somewhat eastward, and the two populations have recently come in contact. If the two forms were unable to interbreed when their expanding ranges met, it would be an example of ________.

A) prezygotic isolation

B) reinforcement

C) allopatric speciation

D) sympatric speciation

C) allopatric speciation

Most causes of speciation are relatively slow in that they may take many generations to see changes, with the exception of ________.

A) polyploidy

B) reinforcement

C) colonization

D) natural selection

A) polyploidy

Two researchers experimentally formed tetraploid frogs by fertilizing diploid eggs from Rana porosa brevipoda with diploid sperm from Rana nigromaculata. When they mated these tetraploid frogs with each other, most of the offspring that survived to maturity were tetraploid, with chromosome sets of both diploid parent species. Based on these results, if this type of tetraploid formed in the wild, what would be the result? (Reference: Y. Kondo and A. Kashiwagi. 2004. Experimentally induced autotetraploidy and allotetraploidy in two Japanese pond frogs. Journal of Herpetology 38(3):381−92.)

A) The two parent species would interbreed and fuse into one species.

B) The two parent species would recognize each other as mates.

C) The tetraploids would be reproductively isolated from both parent species.

D) The tetraploids would be selected against.

C) The tetraploids would be reproductively isolated from both parent species.

How can reproductive barriers form sympatric populations while their members remain in the same geographic area?

A) increased gene flow

B) polyploidy

C) decreased sexual selection

D) habitat sharing

B) polyploidy

Two species of tree frogs that live sympatrically in the northeastern United States differ in ploidy: Hyla chrysoscelis is diploid, and Hyla versicolor is tetraploid. The frogs are identical in appearance, but their mating calls, which females use to find mates, differ. Which difference most likely evolved first?

A) polyploidy

B) difference in mating calls

C) habitat differentiation

D) Polyploidy and different mating calls must have evolved at the same time.

A) polyploidy

In a hypothetical situation, a certain species of flea feeds only on pronghorn antelopes. In the western United States, pronghorns and cattle often associate with one another in the same open rangeland. Some of these fleas develop a strong preference for cattle blood and mate only with other fleas that prefer cattle blood. The host mammal can be considered as the fleas' habitat. If this situation persists, and new species evolve, this would be an example of ________.

A) sympatric speciation and habitat isolation

B) sympatric speciation and temporal isolation

C) allopatric speciation and habitat isolation

D) allopatric speciation and gametic isolation

A) sympatric speciation and habitat isolation

The difference between geographic isolation and habitat differentiation (isolation) is the ________.

A) relative location of two populations as speciation occurs

B) speed (tempo) at which two populations undergo speciation

C) amount of genetic variation that occurs among two gene pools as speciation occurs

D) identity of the kingdom or domain in which these phenomena occur

A) relative location of two populations as speciation occurs

Among known plant species, which of these have been the two most commonly occurring phenomena that have led to the origin of new species?

A) allopatric speciation and sexual selection

B) allopatric speciation and polyploidy

C) sympatric speciation and sexual selection

D) sympatric speciation and polyploidy

D) sympatric speciation and polyploidy

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

A) allopatric speciation; ecological isolation

B) sympatric speciation; habitat differentiation

C) allopatric speciation; behavioral isolation

D) sympatric speciation; allopolyploidy

B) sympatric speciation; habitat differentiation

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands and is also found on the African mainland, located about two hundred miles away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago.

Using only the information provided in the paragraph, which of the following is the best initial hypothesis for how D. santomea descended from D. yakuba?

A) allopolyploidy

B) autopolyploidy

C) habitat differentiation

D) sexual selection

C) habitat differentiation

On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences.

Which two of the following have operated to increase divergence between mosquitofish populations on Andros?

1. improved gene flow
2. bottleneck effect
3. sexual selection
4. founder effect
5. natural selection

A) 1 and 3

B) 2 and 3

C) 2 and 4

D) 3 and 5

D) 3 and 5

In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. The oceans were completely separated by the isthmus about 3 million years ago.

In the figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1-5), with 1 being the shallowest.

Why should deepwater shrimp on different sides of the isthmus have diverged from each other earlier than shallow-water shrimp?

A) They have been geographically isolated from each other for a longer time.

B) Cold temperatures, associated with deep water, have accelerated the mutation rate, resulting in faster divergence in deepwater shrimp.

C) The rise of the land bridge was accompanied by much volcanic activity. Volcanic ash contains heavy metals, which are known mutagens. Ash fall caused high levels of heavy metals in the ocean sediments underlying the deep water, resulting in accelerated mutation rates and faster divergence in deepwater shrimp.

D) Fresh water entering the ocean from the canal is both less dense and cloudier than seawater. The cloudy fresh water interferes with the ability of shallow-water shrimp to locate mating partners, which reduces the frequency of mating, thereby slowing the introduction of genetic variation.

A) They have been geographically isolated from each other for a longer time.

In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. The oceans were completely separated by the isthmus about 3 million years ago.

In the figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1-5), with 1 being the shallowest.

In which habitat should one find snapping shrimp most closely related to shrimp that live in habitat A4?

A) A3

B) A5

C) B4

D) either A3 or A5

C) B4

In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. The oceans were completely separated by the isthmus about 3 million years ago.

In the figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1-5), with 1 being the shallowest.

Which of these habitats is likely to harbor the most recently diverged species?

A) A5

B) B4

C) A3

D) A1

D) A1

In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. The oceans were completely separated by the isthmus about 3 million years ago.

In the figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1-5), with 1 being the shallowest.

Which habitats should harbor snapping shrimp species with the greatest degree of genetic divergence from each other?

A) A1 and A5

B) A1 and B5

C) A5 and B5

D) Both A1/A5 and B1/B5 should have the greatest, but equal amounts of, genetic divergence

C) A5 and B5

In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. The oceans were completely separated by the isthmus about 3 million years ago.

In the figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1-5), with 1 being the shallowest.

Which factor is most important for explaining why there are equal numbers of snapping shrimp species on either side of the isthmus?

A) the relative shortness of time they have been separated

B) the depth of the sea

C) the number of actual depth habitats between the surface and the sea floor

D) the elevation of the isthmus above sea level

A) the relative shortness of time they have been separated

In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. The oceans were completely separated by the isthmus about 3 million years ago.

In the figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1-5), with 1 being the shallowest.

The Panama Canal was completed in 1914, and its depth is about 50 feet. After 1914, snapping shrimp species from which habitats should be most likely to form hybrids as the result of the canal?

A) A5 and B5

B) A3 and B3

C) A1 and B1

D) A1-A3 and B1-B3 have equal likelihoods of harboring snapping shrimp species that can hybridize.

C) A1 and B1

Plant species A has a diploid number of 12. Plant species B has a diploid number of 16. A new species, C, arises as an allopolyploid from A and B. The diploid number for species C would probably be ________.

A) 14

B) 16

C) 28

D) 56

C) 28