Bio 106 C22-24
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.
2 → 4 → 1 → 3
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
2, 4, 1, 3
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 _____.
28
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
3 and 5
If a plant species with 2n = 14 forms an allopolyploid with a plant species with 2n = 18, what would be the likely diploid (2n) number of the allopolyploid?
32
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 expectations for this gene, what percentage of the population must be heterozygous for this trait?
48%
Which of these habitats is likely to harbor the most recently diverged species?
A1
he Panama Canal was completed in 1914, and its depth is about fifty feet. After 1914, snapping shrimp species from which habitats should be most likely to form hybrids as the result of the canal?
A1 and B1
Which habitats should harbor snapping shrimp species with the greatest degree of genetic divergence from each other?
A5 and B5
Evolution in a population of island iguanas can be caused by the following agent(s):
All of the above.
Refer to the figure above. In their investigation of natural selection on Mc1r alleles (the gene that determines coat color) in Arizona pocket mice, Hoekstra et al. determined the frequency of the D and d alleles in each population. They also determined the frequency of alleles for two neutral mitochondrial DNA genes (genes that do not affect and are not linked to coat color). Why did the researchers include the mitochondrial DNA genes as part of their experimental design?
Allele change for the neutral mitochondrial genes serves as a control and gives information on any general background genetic difference among these populations.
Which of the following statements explains why animals are less likely than plants to speciate by polyploidy?
Animals self-fertilize less often than plants, so diploid gametes are less likely to fuse.
Genetic drift occurs in a population. Which of the following statements might be true?
Any of the statements can be true.
In which habitat should one find snapping shrimp most closely related to shrimp that live in habitat A4?
B4
Which is not a limitation when understanding the fossil records
Berksonian bias
What is the best way to promote fusion between two related populations of mosquitofish, one of which lives in a predator-rich pond and the other of which lives in a predator-poor pond?
Build a canal linking the two ponds that permits free movement of mosquitofish, but not of predators.
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
ale frogs give calls that attract female frogs to approach and mate. Researchers examined mating calls of closely related tree frogs in South America. If reinforcement is occurring, what would you expect if you compare the calls of the two species in zones of sympatry versus zones of allopatry?
Calls would be more different in areas of sympatry.
A researcher wants to know if gene flow is contributing to evolution of drought tolerance of pitcher plants in a specific bog. As a control, she should
Determine if the population is in Hardy-Weinberg equilibrium.
Refer to the figure above. Which of the following forms a monophyletic group?
E, F, and G
Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true?
Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted.
Which of the following statements best summarizes evolution as it is viewed today?
Evolution is the differential survival and reproduction of the most-fit phenotypes.
which is an ancestral trait?
Fur in the ancient mammals such as xenarthrans
Which of the graphs above best represents the relationship between the intensity of directional selection and the genetic variation present within a population?
Graph B
Which of the following statements about species, as defined by the biological species concept, is (are) correct? I. Biological species are defined by reproductive isolation. II. Biological species are the model used for grouping extinct forms of life. III. All members of a species can potentially interbreed.
I and III
Male frogs give calls that attract female frogs to approach and mate. Researchers examined mating calls of closely related but separate species of tree frogs in South America. What outcomes could possibly occur where the ranges of two species overlap? I) The species will interbreed, eventually fusing over time. II) A stable hybrid zone will form if hybrids are better adapted to the area of overlap than either parent species is. III) Species will continue to diverge and be isolated by behavioral or genetic mechanisms.
I, II, and III
Fly species W, found in a certain part of the island, produces fertile offspring with species Y. Species W does not produce fertile offspring with species X or Z. If no other species can hybridize, then which of the following statements about species W and Y are true? I) Species W and Y have genomes that are still similar enough for successful meiosis to occur in hybrid flies. II) Species W and Y have more genetic similarity with each other than either did with the other two species. III) Species W and Y may fuse into a single species if their hybrids remain fertile over the course of many generations.
I, II, and III are correct.
which of the following homology (or) homologies is/are useful to make the phylogenetic trees (I) Genetic homology (II) Developmental homology (III)Structural homology
I,II, and III
Swine are vulnerable to infection by bird flu virus and human flu virus, which can both be present in an individual pig at the same time. When this occurs, 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 new virus, and if the new virus is introduced to an environment lacking Tamiflu, then what is most likely to occur?
If the Tamiflu-resistance gene involves a cost, it will experience directional selection leading to reduction in its frequency.
Why doesn't inbreeding depression, by itself, cause evolution?
It does not change the population's allele frequencies.
What must be true of any organ described as vestigial?
It must be homologous to some feature in an ancestor.
which is the first theory to suggest that species are not static and evolves through time
Lamarckian Theory
How do mass extinctions differ from background extinctions?
Mass extinctions cause a larger proportion of organism to go extinct than background extinctions
n 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?
Mutation led to increased genetic variation.
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. Refer to the figure above. Is this population in Hardy-Weinberg equilibrium?
No; there are more homozygotes than expected.
DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Instead, DDT is largely useless against many insects. Which of these would have prevented this evolution of DDT resistance in insect pests?
None of the insect pests would have genetic variations that resulted in DDT resistance.
Inbreeding is said to increase ......... population I) homozygous dominant II) homozygous recessive III) heterozygous dominant
Only I and II
Why is speciation by polyploidy more likely in plants than in animals?
Plant gametes can be produced by meiosis from somatic cells that have undergone many rounds of mitosis.
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?
Postzygotic isolation exists between the two frog species.
Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree?
Relationships between DNA sequences among the species did not match relationships between skeletal patterns.
Biological fitness is best defined as
Relative the ability of an individual to produce offspring that survive and reproduce.
When nonrandom mating occurs in a population so that individuals prefer to mate with similar individuals, allele frequencies should
Remain the same, but homozygotes will be overrepresented in the population.
Parasitic species tend to have simple morphologies. Which of the following statements best explains this observation?
Simple morphologies convey some advantage in most parasites.
Suppose that a group of male pied flycatchers migrated from a region where there were no collared flycatchers to a region where both species were present. Assuming events like this are very rare, which of the following scenarios is LEAST likely?
The frequency of hybrid offspring would decrease.
Which of the following could be a vicariance event for species in that habitat?
The level of water in a lake recedes, creating two lakes where there used to be one.
laytonia 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?
The percentage of pink flowers should increase over time.
Two frog populations (same species) living in two neighboring lakes sing slightly different courtship songs. Increased irrigation makes the land between the two lakes wetter, allowing frogs to expand their ranges to the area between the lakes. Females in both populations prefer loud frogs to quieter frogs, but do not distinguish between the two slightly different songs. Assuming that courtship song differences have a genetic basis, predict what will likely happen to the songs of the two frog populations.
The songs will become more similar to each other.
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? (Y. Kondo and A. Kashiwagi. 2004. Experimentally induced autotetraploidy and allotetraploidy in two Japanese pond frogs. Journal of Herpetology 38(3):381-92.)
The tetraploids would be reproductively isolated from both parent species.
Bird guides once listed the myrtle warbler and Audubon's warbler as distinct species. Recently, these birds have been classified as eastern and western forms of a single species, the yellow-rumped warbler. Which of the following pieces of evidence, if true, would be cause for this reclassification?
The two forms interbreed often in nature, and their offspring have good survival and reproduction
About thirteen different species of finches inhabit the Galápagos Islands today, all descendants of a common ancestor from the South American mainland that arrived a few million years ago. Genetically, there are four distinct lineages, but the thirteen species are currently classified among three genera. The first lineage to diverge from the ancestral lineage was the warbler finch (genus Certhidea). Next to diverge was the vegetarian finch (genus Camarhynchus), followed by five tree finch species (also in genus Camarhynchus) and six ground finch species (genus Geospiza). If the six ground finch species have evolved most recently, then which of these is the most logical prediction?
Their genomes should be more similar to each other than are the genomes of the five tree finch species.
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?
Their winter habitat has no bearing on their degree of reproductive isolation.
If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, what would happen in environments that lack antibiotics?
These bacteria would be outcompeted and replaced by bacteria that have lost these genes.
Why should deepwater shrimp on different sides of the isthmus have diverged from each other earlier than shallow-water shrimp?
They have been geographically isolated from each other for a longer time.
There is an island in the middle of a large river that houses a large population of ants. Damming of the river causes the island to flood and only the highest points of the island are now above water. The ants cannot swim, so are now in multiple isolated populations. Which of the following best describes this event?
This situation represents isolation by vicariance.
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 explanations best explains what happened?
Triazine-resistant weeds were more likely to survive and reproduce.
Which of the following is a fitness trade-off (compromise)?
Turtle shells provide protection but are heavy and burdensome when moving.
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, each of these structures presented greater costs than benefits.
There is a population of beetles that typically have black wings. A scientist studying these beetles knows that their eggs hatch in early spring, the young insects grow through the late spring and summer, they lay eggs in the early fall, and they die in the early winter. Recently some beetles have been born with white wings. Early in life, the black- and white-winged beetles seem to be very similar in number of mating events, eggs laid, and survival rates, but shortly after laying their eggs the white beetles die and there are only black-winged beetles during the late fall. Which of the following is a true statement about the beetles?
White- and black-winged beetles have equal fitness.
The figure above shows the distribution of pocket-mouse coat colors in several Arizona populations found either on light-colored granite substrate or on dark volcanic rock (dark substrate). The Melanocortin-1 receptor (Mc1r) alleles, D and d, differ by four amino acids. Mice with DD and Dd genotypes have dark coats, whereas mice with the dd genotype are light colored. What sort of genotype frequencies might you expect to find in the Xmas, Mid, and O'Neill populations?
Xmas-high dd frequency; Mid-high DD frequency, O'Neill-high Dd frequency
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 behavioral reproductive isolating mechanism
populations of mocking jays look very similar, but the males have courtship that looks very different. What functioning would this difference in dance likely serve if the populations came in contact?
a behavioral reproductive isolating mechanism
Refer to the paragraph on dark-eyed junco birds. 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 founder effect
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 genetic bottleneck
an earthquake at Haiti (2010) decimated stygian owl population, killing 95% of the owls. The surviving populations happens to have large-sized dusky colored, on average, than the initial population. If color of owls is genetically determined, what effect has the stygian owl population experienced during the earthquake?
a genetic bottleneck
The largest unit within which gene flow can readily occur is _____.
a species
Many crustaceans (for example, lobsters, shrimp, and crayfish) use their tails to swim, but crabs have reduced tails that curl under their shells and are not used in swimming. This is an example of _____.
a vestigial trait
The sickle-cell allele is pleiotropic (that is, it affects more than one phenotypic trait). Specifically, this allele affects oxygen delivery to tissues and affects one's susceptibility to malaria. Under conditions of low atmospheric oxygen availability, individuals heterozygous for this allele can experience life-threatening sickle-cell "crises." Such individuals remain less susceptible to malaria. Thus, pleiotropic genes/alleles reveal that _____.
adaptations are often compromises
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 _____.
allopatric speciation
How are two different species most likely to evolve from one ancestral species?
allopatrically, after the ancestral species has split into two populations
A hybrid zone is properly defined as
an area where mating occurs between members of two closely related species, producing viable offspring
A hybrid zone is properly defined as _____.
an area where mating occurs between members of two closely related species, producing viable offspring
The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two populations meet again and _____.
an increasing number of viable, fertile hybrids is produced over the course of the next one hundred generations
When individuals are produced when mutations results in a doubling a chromosome number and all the chromosomes come from the same species
autopolyploidy
Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian Islands have different elaborate courtship rituals. These rituals involve fighting other males and making stylized movements that attract females. What type of reproductive isolation does this represent?
behavioral isolation
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 type of reproductive isolation operates to keep the mosquitofish isolated, even when fish from different ponds are reunited in the same body of water?
behavioral isolation
On the banks if chesapeake bay, stingrays, Urolophus halleri populations live in various, isolated, water ponds that were once united with atlantic ocean. Currently, some ponds contain male stingrays that developed a blue colored claspers and tails; while other ponds contain sting rays with normal white colored claspers. When placed together in the same body of water, the two kinds of female stingrays exhibit exclusive breeding preferences. Which type of reproductive isolation operates to keep the stingrays isolated, even when stingrays from different ponds are reunited in the same body of water?
behavioral isolation
Of the following anatomical structures, which is homologous to the bones in the wing of a bird?
bones in the flipper of a whale
Natural selection _____.
can favor beneficial mutations
Cystic fibrosis is a genetic disorder in homozygous recessive (ff) humans that typically causes death in the early thirties. Over time, we would expect the f allele frequency to _____ for this trait.
decrease
Students in Bio 106 Lab identified that small lizards that grows in HU trees had higheer reproductive success than larger lizards. Small lizards can easily run and less predated by the hawks, while the larger lizards are slow and easily predated. Thus, we can hypothesized that lizard size will _________ as the students closer to their graduation
decrease
Currently the only predators of Galápagos marine iguanas are Galápagos hawks. Iguana body size is not correlated with risk of hawk predation, although small iguanas can sprint faster than large iguanas. If predators (for example, cats) that preferably 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 is the most predictable outcome of increased gene flow between two populations?
decreased genetic difference between the two populations
One morphological feature of modern cetaceans is a vestigial pelvic girdle. If it is determined that the cetacean lineage diverged from the artiodactyls' lineage after the divergence of pigs and other artiodactyla, then the vestigial pelvic girdle of cetaceans should be considered a shared _____.
derived character of the cetaceans
The observation that island D. yakuba are more closely related to mainland D. yakuba than island D. yakuba are to D. santomea is best explained by proposing that D. santomea _____.
descended from an original colony of D. yakuba, of which there are no surviving members. The current island D. yakuba represent a second colonization event from elsewhere.
Which of the following is the best modern definition of evolution?
descent with modification
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 _____.
determine if hair length is heritable
Similar gill pouches in embryos of a chick, human, and cat are an example of _____.
developmental homology
The two populations are _____.
different subspecies, under the morphological species concept
the disadvantages of biological species concept is that it cannot be applied to?
dinosaur fossils
The recessive allele that causes phenylketonuria (PKU) is harmful, except when an infant's diet has appropriate levels of the amino acid phenylalanine. What maintains the presence of this harmful allele in a population's gene pool?
diploidy
In seedcracker finches from Cameroon, small- and large-billed birds specialize in cracking soft and hard seeds, respectively. If long-term climatic change resulted in all seeds becoming hard, what type of selection would then operate on the finch population?
directional selection
Darwin and Wallace's theory of evolution by natural selection was revolutionary because it _____.
dismissed the idea that species are constant and emphasized the importance of variation and change in populations
The historic jamestown in virginia is the first permanent english settlement in United States. The archaelogist found there is strikingly unique DNA feature that exist between the people who lived in Jamestown and the bone samples found in modern England. The movement of populations is an example of
dispersal
Three-spined stickleback fish (Gasterosteus aculeatus) show substantial heritable 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 of the following is most likely to produce an African butterfly species in the wild whose populations show two strikingly different color patterns?
disruptive selection
A researcher notices that in a certain moth species, some females prefer to feed and lay eggs on domesticated solanaceous plants like potatoes and tomatoes. Other females prefer to feed and lay eggs on wild solanaceous plants like Datura. Both male and female moths primarily use scent to find these plants from afar. Females tend to mate where they feed, and the researcher finds a genetic basis for scent preference in these moths. Based on the above information, what might be occurring in this moth species?
divergence in sympatry
Which of the following, if discovered, could refute our current understanding of the pattern of evolution?
diverse fossils of mammals in Precambrian rock
Mutation is the only evolutionary mechanism that _____.
does little to change allele frequencies
After the drought of 1977, researchers on the island of Daphne Major hypothesized that medium ground finches that had large, deep beaks, survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. If this hypothesis is correct, what would you expect to observe if a population of these medium ground finches colonizes a nearby island where Tribulus cistoides is the most abundant food for the next 1000 years? Assume that (1) even the survivors of the 1977 drought sometimes had difficulty cracking the tough T. cistoides fruits and would eat other seeds when offered a choice; and (2) food availability is the primary limit on finch fitness on this new island.
evolution of yet larger, deeper beaks over time
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 model?
f(A1) = 0.9700, f(A2) = 0.0300
The purpose of the natural selection is to make perfect human beings i.e. to make better alleles
false
what was the central claim of Aristotle about the species
fixed
_______ is the trace of organisms that lived in the past
fossil
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 likely explains the genetic uniqueness of this population?
founder effect and genetic drift
Soon after Huricane Irma (2017), coastal Florida obsered a new species of Ocellated gecko, yellow colored lizards that are native to western caribean islands Antigua and Barbuda islands. Lets say in 2030, biologists find the genome of Florida lizards are genetically diverse from that of the native Caribbean lizards. What type of event caused the evolution of Ocellated gecko?
founder's effect
When imbalances occur in the sex ratio of sexual species that have two sexes (that is, other than a 50:50 ratio), 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. This is most clearly an example of _____.
frequency-dependent selection
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 _____.
gametic isolation
What does the biological species concept use as the primary criterion for determining species boundaries?
gene flow
Which of the following does not tend to promote speciation?
gene flow
when an individual leaves the population, joins another, breeds, ......... is said to occur
gene flow
which one of the factors tend to equalize the allele frequencies among populations
gene flow
In hybrid zones where reinforcement is occurring, we should see a decline in _____.
gene flow between distinct gene pools
Although each of the following has a better chance of influencing gene frequencies in small populations than in large populations, which one most consistently requires a small population as a precondition for its occurrence?
genetic drift
Which of the following describes the most likely order of events in allopatric speciation?
genetic isolation, genetic drift, divergence
There are currently two large, permanent bridges that span the Panama Canal. The bridges are about eight miles apart. If snapping shrimp avoid swimming at night and avoid swimming under shadows, then what do these bridges represent for the snapping shrimp?
geographic barriers
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. (N. Knowlton, L. A. Weigt, L. A. Solorzano, D. K. Mills, and E. Bermingham. 1993. Divergence in proteins, mitochondrial DNA, and reproductive incompatibility across the Isthmus of Panama. Science 260:1629-32.) Refer to the paragraph about the formation of the Isthmus of Panama. If the isthmus formed gradually rather than suddenly, what pattern of genetic divergence would you expect to find in these species pairs?
greater percentage of difference in DNA sequence between species that inhabit deep water than between species that inhabit shallow water
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
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?
habitat isolation
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 fourteen million years ago. Which of the following reduces gene flow between the gene pools of the two species on Sao Tomé, despite the existence of hybrids?
hybrid sterility
Reinforcement is most likely to occur when _____.
hybrids have lower fitness than either parent population
Wikelski and Romero (2003) found that large marine iguanas had higher reproductive success than smaller iguanas did. However, the large iguanas were generally in poor body condition because they could not eat enough; at higher temperatures their foraging efficiency improved, allowing them to eat more. Thus, Wikelski and Romero hypothesized that iguana size will _____ as global warming gradually increases air and water temperatures in the Galápagos Islands.
increase
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?
increased variation in beak size and shape over time
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 warm-blooded. The fossils of Thrinaxodon are consistent with the hypothesis that _____.
mammals evolved from a reptilian ancestor
Mating fails because of the male and female reproductive structures are incompatible
mechanical
Genetic variation _____.
must be present in a population before natural selection can act upon the population
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. The actual forelimbs of these mammals do not seem to be optimally arranged because _____.
natural selection is generally limited to modifying structures that were present in previous generations and in previous species
a biological term that is used to describe the range of ecological resources for species to be used
niche
In a small population of alpine foxes, you observe increased ear length over a ten-year period. Can you conclude that increase in ear length is advantageous in this population?
no
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-nineteenth 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?
no
For a biologist studying a small fish population in the lab, which Hardy-Weinberg condition is easiest to meet?
no gene flow
For biologists studying a large flatworm population in the lab, which Hardy-Weinberg condition is most difficult to meet?
no mutation
Vestigial traits and neutral changes in DNA sequences are good examples of _____.
nonadaptive traits
The Irish "elk" described by Georges Cuvier suggests that _____.
organisms could go extinct
what distinguishes a morphospecies?
physical structure
if there is change in single nucleotides of the ancestor species leading to a new descendant species ________ is said to occur
point mutation
Most causes of speciation are relatively slow, in that they may take many generations to see changes, with the exception of _____.
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?
polyploidy
an event that does not promote new speciation is?
polyploidy
Individuals of the same species living in the same area at the same time are called
population
hybrid offspring do not develop normally and die as embryos. This is an example of
postzygotic
If the low number of hybrid flies in the hybrid zone, relative to the number of D. santomea flies there, is due to the fact that hybrids are poorly adapted to conditions in the hybrid zone, and if fewer hybrid flies are produced with the passage of time, these conditions will most likely lead to _____.
reinforcement
The difference between geographic isolation and habitat differentiation (isolation) is the _____.
relative locations of two populations as speciation occurs
Which statement represents the best explanation for the observation that the nuclear DNA of wolves and domestic dogs has a very high degree of sequence homology? Dogs and wolves______.
share a very recent common ancestor
the mortability of babies that are under-weight and over-weight is an example of
stabilizing natural selection
Examine the figure above. What type of selection for body size appears to be occurring in these marine iguanas?
stabilizing selection
Heterozygote advantage should be most closely linked to which of the following?
stabilizing selection
Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer or more than this have reduced fitness. Which of the following terms best describes this situation?
stabilizing selection
The same basic internal organs (kidneys, stomach, heart, lungs) are found in frogs, birds, snakes, and rodents. This is primarily an example of _____.
structural homology
The origin of a new plant species by hybridizing two existing species, coupled with accidents during cell division, is an example of _____.
sympatric speciation and allopolyploidy
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 _____.
sympatric speciation and habitat isolation
Among known plant species, which of these have been the two most commonly occurring phenomena that have led to the origin of new species?
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?
sympatric speciation; habitat differentiation
Except ......... all other process can happen when a group of species move from one population to another population
sympatry
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. These new arrivals _____.
tend to retard adaptation to the new food plants
What is the disadvantage of applying species concept to a intact fossil of Prunus dulcis that was found in Egyptian pyramids?
the biological species concept cannot be applied
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 _____.
the founder effect
The inability of organisms to evolve anything that could be an advantage reflects _____.
the limits of historical constraints
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. (N. Knowlton, L. A. Weigt, L. A. Solorzano, D. K. Mills, and E. Bermingham. 1993. Divergence in proteins, mitochondrial DNA, and reproductive incompatibility across the Isthmus of Panama. Science 260:1629-32.) Refer to the paragraph about the formation of the Isthmus of Panama. The sister populations on opposite sides of the isthmus are true species under which species concept?
the morphological species, biological species, and phylogenetic species concepts
Which factor is most important for explaining why there are equal numbers of snapping shrimp species on either side of the isthmus?
the relative shortness of time they have been separated
Cave-dwelling animals that lost their visions is an example of_____.
transitional feature
a monophyletic group also called clade or tribe consists of ancestral population only of descendants.
true
If x indicates the fossils of two closely related species, neither of which is extinct, then their remains may be found in how many of these strata?
two strata
a hypothetical situation, the National Park Service, which administers Grand Canyon National Park in Arizona, builds a footbridge over the Colorado River near the bottom of the canyon. The footbridge permits migration to occur between populations of two closely related antelope squirrels. Previously, one type of squirrel had been restricted to the terrain south of the river, and the other type had been restricted to terrain on the north side of the river. Immediately before and ten years after the bridge's completion, researchers collected ten young antelope squirrels from both sides of the river, took blood samples, and determined frequencies of alleles unique to the two types of antelope squirrels (see the following graphs). The data in the previous graphs indicate that _____.
two-way migration of squirrels occurred across the bridge, but without hybridization
Which of the following evidence most strongly supports the common origin of all life on Earth? All organisms _____.
use essentially the same genetic code
Researchers discovered that a new strain of bacteria that cause tuberculosis (M. tuberculosis) taken from a dead patient has a point mutation in the rpoB gene that codes for part of the RNA polymerase enzyme. This mutant form of RNA polymerase does not function as well as the more common form of RNA polymerase. A commonly used antibiotic called rifampin does not affect the mutant rpoB bacteria. A researcher mixes M. tuberculosis with and without the rpoB mutation and adds the bacteria to cell cultures. Half the cell cultures contain only standard nutrients, while the other half of the cell cultures contain rifampin and the standard nutrients. After many cell generations, the researcher finds that _____.
very few M. tuberculosis in the standard nutrient cell cultures carry the rpoB gene mutation, but almost all of the M. tuberculosis in the cell cultures with rifampin carry the rpoB mutation
________ is a reduced or incompletely developed trait in a living organisms that has no function, but is clearly similar to functioning organs or structures in a closely related species
vestigial
if a physical barrier such as mountain range or river splits the geographic range of a species,......... is said to take place
vicariance