Mastering Biology CH 22-24

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 evolutionary tree?

-[=z{x/y

In a Hardy-Weinberg population with two alleles A1 and A2 that are in equilibrium, the frequency of the allele A2 is 0.3. What is the frequency of individuals that are homozygous for this allele?

0.09

In a Hardy-Weinberg population with two alleles A1 and A2 that are in equilibrium, the frequency of allele A2 is 0.2. What is the frequency of individuals that are heterozygous for this allele?

0.32

A scientist samples a population of butterflies and finds that 56% are heterozygous at a particular locus. If the population is in Hardy-Weinberg equilibrium, what should be the frequency of the homozygous individuals in this population?

0.44

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. One allele (T1) codes for an enzyme that makes the toxin, and another allele (T2) codes for a nonfunctional enzyme that cannot produce the toxin. Heterozygotes produce an intermediate amount of toxin. The allele frequency of T1 is determined to be 0.6 and the allele frequency of T2 is 0.4. What is the expected frequency of heterozygotes if the population is in Hardy-Weinberg equilibrium?

0.48

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 (A2A2), the same percent 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 most likely heterozygous (A1A2) for this trait?

0.50

In peas, a gene controls flower color such that R1 = purple and R2 = white. The purple allele is dominant to the white allele. 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?

0.80

A species of moth lays eggs on oak trees in spring and summer. Spring caterpillars eat oak flowers and look like oak flowers. Summer caterpillars eat oak leaves and look like twigs. To investigate how the same population of moths can produce such variable caterpillars, a researcher collected eggs from a population of moths and allowed them to hatch and grow under the conditions shown in the table below. Comparison of which treatments would allow the researcher to assess the effect of food type on caterpillar morphology?

1, 3, 5, and 7 versus 2, 4, 6, and 8

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

28

A species of moth lays eggs on oak trees in spring and summer. Spring caterpillars eat oak flowers and look like oak flowers. Summer caterpillars eat oak leaves and look like twigs. To investigate how the same population of moths can produce such variable caterpillars, a researcher collected eggs from a population of moths and allowed them to hatch and grow under the conditions shown in the table below. If day length causes the different development of caterpillars, which treatments will most likely produce twig-like caterpillars rather than flower-like caterpillars?

3, 4, 7, and 8

Suppose 64% of the individuals in 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 percent of the population must be heterozygous for this trait?

48%

The figure shows an outcrop of sedimentary rock whose strata are labeled A-D. If x indicates the location of fossils of two closely related species, then fossils of their most-recent common ancestor are most likely to occur in which stratum?

C

Pigs are vulnerable to infection by bird flu virus and human flu virus, both of which can be present in an individual pig at the same time. When both viruses infect a pig simultaneously, it is possible for genes from bird flu virus and human flu virus to be combined. If the human flu virus contributes a gene for Tamiflu resistance (Tamiflu is an antiviral drug) to the bird flu virus, and if this new virus is introduced to an environment lacking Tamiflu, then which of the following scenarios is most likely to occur?

If the tamiflue-resistance gene involves a cost, it will experience directional selection, leading to reduction in its frequency

Which of the following statements best describes Linnaeus' method of classifying organisms?

Linnaeus grouped organisms into increasingly more inclusive categories

An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population has broader stripes, on average, than the initial population. If broadness of stripes is genetically determined, which of the following processes most likely caused the change?

a bottleneck effect

A small number of birds arrive on an island from a neighboring larger island. This small population begins to adapt to the new food plants available on the island, and their beaks begin to change. About twice a year, one or two more birds from the neighboring island arrive. Which of the following effects is most likely to result from the immigration?

a decraese in a birds' adaption to the new food plants

Which of the following observations would provide evidence supporting Lamarck's proposed evolutionary mechanism of "inheritance of acquired characteristics"?

a decrease in tail length in dogs after 20 generations of dogs that had their tais docked (cut off) as puppies

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

a tetraploid plant is more likely to self-fertilize and produce viable offspring, but a tetraploid animal would need a second, independently-produced tetraploid with which to mate

Which of the following statements about vestigial structures is accurate?

a vestigial structure in species A can be homogolous to a functional structure in species B

Which of the following observations most strongly supports the common origin of all life on Earth?

all organisms use essentially the same genetic code

Which of the following statements is accurate with regard to a population in Hardy-Weinberg equilibrium?

allele frequencies should not change from one generation to the next

Which of the following situations leads to microevolution?

alleles move between populations that differ in allele frequencies

House finches (birds) occurred only in western North America until 1939, when a few individuals were released in New York City. These individuals established a breeding population and gradually expanded their range. The western population also expanded its range somewhat eastward, and the two populations have recently come in contact. Which of the following terms best describes the process that had occurred if the two forms did not interbreed when their expanding ranges met?

allopatric speciation

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

allopatrically, after the ancestral species has split into two populations

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

an area where mating occurs between members of two closely related species, producing viable offspring

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

an earthquake that pushes debris into the middle of a lake and makes two unconnected lakes

Which of the following factors would most likely cause an increase in population size of a prey animal?

an improvement in eyesight

Imagine a human population with an extremely low frequency of sickle cell alleles. Which of the following changes is most likely in the human population 15 generations after introducing a mosquito population that carries the malaria parasite?

an increase in the sickle cell allele

One possible outcome of hybridization is fusion of two species. Which of the following conditions is most likely to increase the probability of fusion of the two species as a result of hybridization?

an increasing number of viable, fertile hybrids is produced over the course of the next 100 generations

Given what we know about evolutionary biology, which of the following places would be the most likely to have the highest number of species that are unique to the area (that is, that had evolved in that place). Assume that the conditions have existed for at least a few million years.

an isolated group of ocean islands

Which of the following statements best defines artificial selection?

artificial selection is process in which humans decide which plants and/or animals will and will not breed

Three populations of crickets look very similar, but the males have different courtship songs. If the cricket populations were to contact each other in the wild, the different courtship songs would most likely function as which type of reproductive isolating mechanism?

behavioral

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

behavioral isolation

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

biological

Of the following anatomical structures, which is most homologous to the bones in the wings of a bird?

bones in the flippers of a whale

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

breeding in zoos is most likely the effect of isolation from available, appropiate mates

Cotton-topped tamarins are small primates with tufts of long white hair on their heads. While studying these creatures, a scientist noticed that males with longer hair get more opportunities to mate and that they father more offspring than males with shorter hair. Which of the following possible studies would be the best design for testing if longer hair is an adaptive trait? Assume that hair length is a trait that is inherited.

capture a group of males with long hair at random, and cut the hair very short in half of the males; then compare the number of matings of males with thier hair left unchanged vs. males with shortened hair

A team of scientists plans to study divergence of populations and needs to maximize the rate of divergence to see results within the period of their grant funding. They will form a new population by taking some individuals from a source population and isolating them so the source and new populations cannot interbreed. Which of the following strategies would maximize the likelihood of seeing divergence between the source and new populations in this study?

choosing individuals from one extreme of the population to form the new population and placing the new population in a novel environment

Imagine a small herbaceous flowering plant whose conservation status is "endangered." Which of the following possible experiments would best test if a lack of genetic variability was partially responsible for low population numbers?

compare seed production in plants that are hand pollinated with pollen from with pollen from nearby individuals versus individuals 10 kilometers away

A researcher has maintained a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, the viability of the flies decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, which of the following approaches would be the best way to reverse this trend of decreased viability?

cross the flies with flies from another lab

Which of the following statements best describes Darwin's theory of evolution by natural selection?

darwin's theory emphasized that populations vary and change over time

Two scientists measured the snout-to-vent (anus) length of Galapagos marine iguanas (lizards) and observed the percent survival of different-sized animals, all of the same age. The graph shows the log snout-vent length (SVL, a measure of overall body size) plotted against the percent survival of these different size classes for males and females. (Data from M. Wikelski and L. Michael Romero. Body size, performance and fitness in Galapagos marine iguanas. Integrative and Comparative Biology 43:376-386 [2003].)Currently, the only predators of Galapagos marine iguanas are Galapagos hawks. Although small iguanas can sprint faster than large iguanas, iguana body size is not correlated with risk of hawk predation. If predators (for example, cats) that preferentially catch and eat slower iguanas are introduced to the island, iguana body size is likely to ________ in the absence of other factors; the iguanas would then be under ________ selection.

decrease ; directional

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

decreased gebetic difference between the two populations

In a very large population, a measurable trait has the distribution pattern shown in the diagram. Assume the trait is genetically determined. If there is no gene flow and the curve shifts to the left or to the right, which of the following processes is most likely occurring?

directional selection

Emerald ash borers are beetles whose larvae eat the leaves of ash trees. Without treatment of the trees, the beetles usually kill all ash trees in an area within 10 years. Which of the following events would provide the best possible avenue for saving the ash trees?

discovery of a gene in ash trees that prevents feeding by emerald ash borers and subsequent breeding of more ash trees with this chemical

A biologist doing a long-term study on a wild spider population observes increased variation in silk thickness. Which of the following processes is the most likely to be affecting the spider population?

disruptive selection

Three-spined stickleback fish (Gasterosteus aculeatus) show substantial genetic variation in gill-raker length related to differences in their diets. Longer gill rakers appear to function better for capturing open-water prey, while shorter gill rakers function better for capturing shallow-water prey. Which of the following types of selection is most likely to be found in a large lake (open water in the middle and shallow water around the sides) with a high density of these fish?

disruptive selection

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

each bird's survival was strongly influenced by the depth and strength of it's beak as the drought persisted

Which of the following reasons best explains why separate populations of a given species are likely to vary genetically from one another?

environmental and weather conditions vary on a small scale

Which of the following statements about evolutionary trees is accurate?

evolutionary trees are considered evolutionary hypothesis

Cystic fibrosis is a genetic disorder in humans where the person has two homozygous recessive alleles for the gene. If the disease is left untreated, it causes severe health problems in the individual. 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?

f( A^1 ) = 0.9700 , f( A^2 ) = 0.0300

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 allele frequencies at many loci from all other populations, including those in their original homeland. Which of the following mechanisms most likely explains the genetic uniqueness of this population?

founder effect and genetic drift

When a species deviates from a 50:50 sex ratio (male to female), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. Which of the following processes most likely causes this pattern?

frequency-dependent selection

Restriction enzymes in bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, they in turn select for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. Which of the following factors is most likely to cause the changes?

frewuency-dependent selection

Studies 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. These patterns indicate that interbreeding occurred before human migration further east. Which evolutionary force most likely generated these results?

gene flow

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

gene flow

The effect of which Hardy-Weinberg condition is affected by population size?

genetic drift

Which of the following statements about genetic variation is accurate?

genetic variation must be present in a population before natural selection can act upon the population

In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp, 15 species on the Pacific side and 15 different species on the Atlantic side. Species live at different water depths. Morphological and genetic data show that Atlantic and Pacific species that live at similar depths are sister species. Geological evidence indicates that the Isthmus of Panama started rising about 10 million years ago and the oceans were completely separated by the isthmus about 3 million years ago. If the isthmus indeed formed gradually, which of the following patterns of genetic differences is most likely in these species pairs?

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

Two species of fruit flies occur on the volcanic, equatorial West African island of Sao Tome that rose from the Atlantic Ocean 14 million years ago. Drosophila santomea occurs only on at higher elevations, while D. yakuba inhabits the lowlands. D. yakuba also occurs on the African mainland. On Sao Tome a hybrid zone between the two species exists at middle elevations. Hybrid males, but not females, are sterile, and hybrids are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Using this information, which of the following phenomena is the best initial hypothesis for how D. santomea descended from D. yakuba?

habitat differentiation

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?

habitat isolation

Fossil evidence indicates that modern whales and other cetaceans (dolphins and porpoises) are closely related to even-toed ungulates (hippopotamuses, pigs, deer, and cows). Which of the following predictions would you make if you wanted to test this idea using the amino acid sequence of hemoglobin?

hemoglobin sequences of whales will be more similar to hippopotumuses than horses

Which of the following statements best explains the need for the "2" in the 2pq term in the Hardy-Weinberg equation?

heterozygotes can come about in two ways

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

hybrid breakdown

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

hybridize species R and S; plant the hybrid offspring in environmental conditions resmbling those of species R, S, and T; follow morphological and genetic changes in the offspring of the hybrids; and compare the observed changes to species T

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

hybrids have lower fitness than either parent population

Which of the following statements best describes the effect of natural selection on a population?

improved match between a population and its environment

Which of the following factors contribute to limiting the capacity of organisms to overreproduce?

inability of individuals to tolerate physical conditions, lack of food, and mortality of predators

Antibiotic resistance in bacteria is an increasingly dangerous public health problem. Which of the following strategies would be most likely to reduce public health problems?

increased funding for research into finding new antibiotics with new mechanisms of action

Over time, humans have steadily increased their movements across the continents of the Earth. Which of the following results has most likely been derived from these movements?

increased gene flow

After a drought in 1977, researchers hypothesized that on the Galapagos 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 the following events is now most likely to occur to finch beaks on this island?

increases variation in beak size and shape over time

Which of these conditions do NOT occur in populations evolving due to natural selection?

individuals pass on most traits that they acquire during their lifetime

It has been observed that organisms on many islands are different from, but closely related to, similar forms found on the nearest continent. Which of the following possible conclusions is best derived from this observation?

island forms are descended from mainland forms

In some jacana (a bird) species, males take care of the eggs and young, and females compete with each other for territories that contain one to several males. Female jacanas are significantly larger than males. Which of these statements is likely NOT an accurate description of this bird species?

males and females have equal variation in reproduction success

Fossils of Thrinaxodon, a species that lived during the Triassic period, have been found in both South Africa and Antarctica. Thrinaxodon had a reptile-like skeleton and laid eggs, but small depressions on the front of its skull suggest it had whiskers and, therefore, fur. Thrinaxodon may have been endothermic (able to generate its own internal heat). Which of the following statements is likely most accurate about Thrinaxodon?

mammals evolved from a relative of Thrinaxodon

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

members of a given species have the potential to interbreed in nature and produce viable, fertile offspring

Restriction enzymes in bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, they in turn select for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. Which of the following outcomes is most likely to occur over the course of evolutionary time?

methylated and nonmethylated strains should be maintained among both bacteria and bacteriophages, with ratios that vary overtime

Recently, a museum scientist discovered a case of preserved grasshoppers that do not resemble any named species. No information about when and where the specimens were collected is available. Which of the following species concepts would be most appropriate to use in identifying and naming the new specimens?

morphological

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. Which of the following events most likely occurred in the rodent populations following the accident?

mutation led to increased genetic variation

A population of dark-eyed junco birds became established near the California coastline, 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. Population sizes in the coastal areas have been reasonably large, and there are significant differences between the coastal and the mountain habitats. The coastal habitat is more open (making birds more visible) and has a lower junco density (decreasing intraspecific competition) than the mountain forests. Given this information, which of the following evolutionary mechanisms is the most likely cause of the difference between the coastal and mountain populations?

natural selection

A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses, whales, and bats. Which of the following statements best explains why the actual forelimbs of these mammals do not seem to be optimally arranged?

natural selection is generally limited to modifying structures that were present in the previous generation

Imagine that you are an explorer who has discovered an isolated land mass in the middle of the Pacific Ocean. You find a predator that resembles a North American wolf except that it lays eggs. You name it the "mid-ocean wolf." The physical similarity between the mid-ocean wolf and the North American wolf is most likely due to which of the following factors?

natural selection that favors similar traits for organisms with similar ecological roles

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

no random mating

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. One allele (T1 ) codes for an enzyme that makes the toxin, and another allele (T2 ) codes for a nonfunctional enzyme that cannot produce the toxin. Heterozygotes produce an intermediate amount of toxin. The researchers measured the abundance of each of the three possible genotypes and compared those numbers to the expected numbers if the population were in Hardy-Weinberg equilibrium. Those numbers are shown in the chart. Based on these data, which answer correctly identifies whether the population is likely in Hardy-Weinberg equilibrium?

no, there are more homozygotes than expected

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

nucleotide variability and average heterozygosity

Which of the following statements is most consistent with data obtained from the fossil record?

older strata carry fossils that differ greatly from living organisms

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

polyploidy

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

polyploidy

Which of the following statements best describes evolution?

populations change genetically from one generation to the next

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

reduced hybrid fertility

Two species of frogs belonging to the same genus occasionally mate, but the embryos stop developing after a day and then die. Which of the following mechanisms keep the species separate?

reduced hybrid viability

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

reproductive isolation

Which of the following statements is most accurate in comparing scientific theories and scientific hypotheses?

scientistic theories are supported by, and make sense of, many observations, whereas scientific hypothesis are narrow, testable ideas

Adult male humans generally have deeper voices than do adult female humans. Which of the following processes was most likely occurring given that the fossil records of apes and humans alike show a trend toward decreasing larynx size in adult females and increasing larynx size in adult males?

sexual dimorphism was developing over time in these species

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

sexual selection and habitat differences

In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp, 15 species on the Pacific side and 15 different species on the Atlantic side. Species live at different water depths. Morphological and genetic data show that Atlantic and Pacific species that live at similar depths are sister species. The sister species on each side of the isthmus cannot interbreed because the water in the canal is fresh water, not salt water, and provides a barrier to reproduction. A sea-level, salt-water canal between the two oceans has been proposed to make transport across the isthmus easier. Which of the following outcomes is the most likely result if such a canal were built?

shallow water species from the two oceans that are sister species would be more likely to interbreed with each other than would be deep water species

In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp, 15 species on the Pacific side and 15 different species on the Atlantic side. Species live at different water depths. Morphological and genetic data show that Atlantic and Pacific species that live at similar depths are sister species. Geological evidence indicates that the Isthmus of Panama started rising about 10 million years ago and the oceans were completely separated by the isthmus about 3 million years ago. If the geological evidence has been misinterpreted and the isthmus had formed very rapidly (in less than 1,000 years), which of the following predictions is most likely?

similar percentage in difference in DNA sequences between all pairs of sister species

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

speciation

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

speciation occured rapidly in geological time

A female fly, full of fertilized eggs, is swept by high winds to an island far from the mainland. She is the first, and only, fly to arrive on this island. Thousands of years later, her numerous offspring occupy the island, but none of them resembles her. There are, instead, several species and their geographic ranges overlap. Each species eats a different kind of food. None of the species can fly and the balancing organs of males differ among species and are now used in courtship displays. Fly species W produces fertile offspring with species Y, but not with species X or Z. Furthermore, X and Z do not hybridize. Which of the following statements about species W and Y is most likely to be accurate?

species W and Y may fuse into a single species if their hybrids remain fertile over the course of many generations

Currently, two living elephant species (X and Y) are classified in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which of the following statements would be accurate?

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

Most Swiss starlings (birds) produce four to five eggs in each clutch. Starlings producing more or less eggs have reduced fitness. Which of the following terms best describes this situation?

stabilizing selection

Two researchers measured the snout-to-vent (anus) length of Galapagos marine iguanas (lizards) and observed the percent survival of different-sized animals, all of the same age. The graph shows the log snout-vent length (SVL, a measure of overall body size) plotted against the percent survival of these different size classes for males and females. (Data from M. Wikelski and L. Michael Romero. Body size, performance and fitness in Galapagos marine iguanas. Integrative and Comparative Biology 43:376-386 [2003].)Based on the data in the figure, what type of selection for body size appears to be occurring in these marine iguanas?

stabilizing selection

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

stable hybrid zones are likely even if hyrids are selected against, if the hybrid zone is narrow and the parental species come in contact frequently

The figure shows an outcrop of sedimentary rock whose strata are labeled A-D. If x indicates the earliest appearance of fossils of two closely related species, neither of which is extinct, then their remains may be found in which of these strata?

strata A and B only

In the western United States, pronghorn antelopes and domestic cattle often associate with one another in the same open rangeland. In a hypothetical situation, a certain species of flea originally fed only on pronghorn antelopes. Some of these fleas developed a strong preference for cattle blood and mated only with other fleas that also preferred cattle blood. The host mammal can be considered as the fleas' habitat. Which of the following processes most likely occurred if the situation persisted and a new species evolved?

sympatric speciation and habitat isolation

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

sympatric speciation; habitat differentiation

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

the biological species concept can be applied because species are, in part, defined by the ability to produce viable, fertile offspring with other species

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

the biological species concept cannot be applied to fossils because the biological species concept uses reproductive isolation to define species

Members of two different species possess a similar-looking structure that they use in a similar way to perform about the same function. Which of the following observations would suggest that the relationship more likely represents homology than convergent evolution?

the embryological developement of the two structures are similar

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

the female is less likely to mate with the immigrant than with a male native to the area

A species of moth lays eggs on oak trees in spring and summer. Spring caterpillars eat oak flowers and look like oak flowers. Summer caterpillars eat oak leaves and look like twigs. To investigate how the same population of moths can produce such variable caterpillars, a researcher collected eggs from a population of moths and allowed them to hatch and grow under the conditions shown in the table below. Which of the following statements is NOT a testable hypothesis in the described experiment?

the food eaten by the female parent as a catepillar determines the different catepillar morphologies

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

the frequency of R declines in hybrids as animals are sampled closer to the range of B. bombina

There are a group of 13 related species of birds on a group of about 20 isolated oceanic islands. These species are grouped into four subgroups, with subgroup 1 evolving first (3 species), subgroup 2 evolving second (1 species), subgroup 3 evolving third (5 species), and subgroup 4 evolving last (6 species). If subgroup 4 evolved most recently, then which of the following statements is the most logical prediction?

the genomes of subgroup 4 should be more similar to each other than the genomes of subgroup 3

In this diagram, each fork represents which of the following ideas?

the most recent common ancestor of the subsequent species

Continental drift (plate tectonics) has moved continents around the globe. Which of the following predictions would be most likely?

the most recently separated continents will have the most closely related species

Claytonia virginica is a plant 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 over white flowers, so that Claytonia with pink flowers produce more seeds 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 predict will most likely happen to the percentage of flower colors in the population over time?

the percentage of pink flowers will increase overtime

In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp, 15 species on the Pacific side and 15 different species on the Atlantic side. Species live at different water depths. Morphological and genetic data show that Atlantic and Pacific species that live at similar depths are sister species. Geological evidence indicates that the Isthmus of Panama started rising about 10 million years ago and the oceans were completely separated by the isthmus about 3 million years ago. Which of the following statements would best explain why the shallow-water sister species are more similar to each other than are the deeper-water species?

the shallow water sister species have been geographically isolated from each other for a shorter time than the the deep water sister species have been

James Hutton and Charles Lyell provided which of the following ideas that paved the way for Darwin's thinking?

the surface features of Earth were formed slowly and gradually and the geological processes are still at work

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

the tetraploids would be reproductively isolated from both parent species

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 (A2A2), 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 (A2A2) has not changed over time?

the two phenotypes are about equally adaptive under labrotory conditions

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

the two species are sympatric and breed during the same seasons of the year

DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Instead, DDT is now largely ineffective against many insects. Which of the following possible actions would have had the best chance of preventing this evolution of DDT resistance?

the use of DDT should have been interspersed with the use of other pesticides that have a different mode of action

Starting from the wild mustard Brassica oleracea, plant breeders have created the strains known as Brussels sprouts, broccoli, kale, and cabbage. Which of the following statements is correct with regard to the wild mustard?

there is enough heritable variation in the wild mustard to permit these different varieties

The diagram shows two sets of islands. Group A is located 2,500 kilometers from the nearest mainland, whereas Group B is located about 25 kilometers from the mainland. Which of the following statements is most likely accurate in comparing the number of unique species (that is, that had evolved in that place) in Island Groups A and B?

there will be more unique species in group A

If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, what would be most likely to happen in environments that lack antibiotics?

these bacteria would be outcompeted and replaced by bacteria that have lost the antibiotic resistant genes

Almost all peppered moths in England were light colored before the Industrial Revolution. However, some dark forms were collected-the dark color is determined by a single, dominant allele of one gene. The bark of trees became darker during the Industrial Revolution in areas where heavy coal use in factories caused pollution. By about 1900, approximately 90% of the moths around industrial areas were dark, whereas light-colored moths were still abundant elsewhere. Apparently, birds could readily find the light moths against the dark trees in industrial areas and, therefore, were eating more light moths. Recently, use of cleaner fuels has resulted in tree bark becoming lighter again and the dark-colored moths have been disappearing. Which of the following statements best explains whether we should consider the forms different species?

they are NOT different species- as shown by the fact that they can interbreed

The common edible frog of Europe is a hybrid between two named species, Rana lessonae and Rana ridibunda. The hybrids were first described in 1758 and have a wide distribution, from France across central Europe to Russia. Both male and female hybrids exist, but when they mate among themselves, they rarely produce offspring. Which of the following statements is the best inference about the two Rana species?

they are different species and postzygotic isolation exists between the two frog species

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

they are more likely to be seperate species at time Z than at time X

The value of the Hardy-Weinberg equation is that it allows scientists to perform which of the following assessments?

to detect whether an evolutionary force is acting upon a population

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; however, after several years, the farmer sees more and more pigweed growing once again in the fields. Which of the following statements best explains the return of pigweed to the farmer's fields?

triazine-resistant weeds were more likely to survive and reproduce than were none-resistant individuals

Over long periods of time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?

under particular circumstances that persisted for long periods, natural selection reduced each of these strctures because they presented greater costs than benefits

Which of the following statements about evolutionary forces is accurate?

unlike the other evolutionary forces, natural selection is the only force that mproves the match between the organism and it's environment