Quiz 5 questions
There is still some controversy among biologists about whether Neanderthals should be placed within the same species as modern humans, or into a separate species of their own. Most DNA sequence data analyzed so far indicate that there was probably little or no gene flow between Neanderthals and Homo sapiens. Which species concept describing species relationship between modern humans and Neanderthals is most applicable in these observations?
biological
Which of the following describes the most likely order of events in allopatric speciation?
genetic isolation, genetic drift, divergence
Which of the following evidence most strongly supports the common origin of all life on Earth? All organisms...
use essentially the same genetic code
Scientific theories...
are supported by, and make sense of, many observations
A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. What is the estimated frequency of allele A in the gene pool?
0.50
A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. What proportion of the population is probably heterozygous (Aa) for this trait?
0.50
You sample a population of butterflies and find that 56% are heterozygous at a particular locus. What should be the frequency of the homozygous individuals in this population?
0.50
In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?
0.80
Why does the fitness of a phenotype depend on frequency-dependent selection?
Because frequency-dependent selection acts against extreme phenotypes
The following questions refer to the figure below, which shows an outcrop of sedimentary rock whose strats 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
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
For which one of the following observations were both Lamarck's hypothesis and Darwin's hypothesis in complete agreement?
Gradual evolutionary change explains why organisms are well-suited to their environments
The question below refers to the following evolutionary tree, in which the horizontal axis represents time (present time is on the far right) and the vertical axis represents morphological change. Which of these is the extant (that is, living) species most closely related to species X?
V
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
Which statement illustrates the connection between natural selection and overreproduction of a population?
Individuals with inherited traits that promote survival tend to have more surviving offspring
Which statement describes unity within a species?
Members have the potential to interbreed in nature and produce viable, fertile offspring
The common edible frog of Europe is a hybrid between two species, Rana lessonae and Rana ridibunda. The hybrids were first described in 1758 and have a wide distribution, from France across central Europe to Russia. Both male and female hybrids exist, but when they mate among themselves, they are rarely successful in producing offspring. What can you infer from this information?
Postzygotic isolation exists between the two frog species
Which one of the following statements best defines artificial selection?
Process of human directed breeding aimed to produce selective traits in selected species
The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V-Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. Which of the five species, labeled V-Z, is the common ancestor of the fewest number of species?
V
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
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
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
The question below refers to the following evolutionary tree, in which the horizontal axis represents time (present time is on the far right) and the vertical axis represents morphological change. Which species is most closely related to species W?
V
The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V-Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. Which of the five common ancestors, labeled V-Z, is the common ancestor of the greatest number of species, both living and extinct?
Y
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 reproduction isolating mechanism
Prior to the work of Lyell and Darwin, the prevailing belief was that Earth is...
a few thousand years old, and populations are unchanging
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
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
According to the biological species concept, for speciation to occur...
at least one gene, affecting one reproductive barrier, must change
Of the following anatomical structures, which is homologous to the bones in the wing of a bird?
bones in the flipper of a whale
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 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. What is the best way to promote fusion between the 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
Speciation...
can involve changes to a single gene
Microevolutions occur when...
changes in allele frequencies in a population occur over generations
Martin Wikelski and L. Michael Romero (Body size, performance and fitness in Galápagos marine iguanas, Integrative and Comparative Biology 43 [2003]:376-86) measured the snout-to-vent (anus) length of Galápagos marine iguanas and observed the percent survival of different-sized animals, all of the same age. The figure below 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. Currently the only predators of Galapagos marine iguanas are Galapagos 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 differences between the two populations
Which Hardy-Weinberg condition is affected by population size?
genetic drift
Which of the following is the best modern definition of evolution?
descent with modification
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
A biologist doing a long-term study on a wild spider population observes increased variation in silk thickness. Which of the following could the spider population be experiencing?
disruptive selection
Macroevolution is...
evolution above the species level
The Dunkers are a religious group that moved from Germany to Pennsylvania in the mid-1700s. They do not marry with members outside their own immediate community. Today, the Dunkers are genetically unique and differ in gene frequencies, at many loci, from all other populations including those in their original homeland. Which of the following mechanisms likely explains the genetic uniqueness of this population?
founder effect and genetic drift
When imbalances occur in the sex ratio of sexual species that have two sexes (i.e., 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
Comparisons of Neanderthal DNA revealed that there are more similarities to non-African DNA than reference sequences from West Africans. Additionally, scientists found that Neanderthal DNA is as closely related to East Asians as to Europeans. This indicates that interbreeding occurred before human migration further east. What process of population genetics generated these results?
gene flow
What does the biological species concept use as the primary criterion for determining species boundaries?
gene flow
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
In the formula for determining a population's genotype frequencies, the "2" in the term 2pq is necessary because...
heterozygotes can come about in two ways
If Darwin had been aware of genes, and of their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement?
if natural selection can change gene frequency in a population over generations, given enough time and genetic diversity, then natural selection can cause sufficient genetic change to produce new species from old ones
After the drought of 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 these events is now most likely to occur to finch beaks on this island?
increased variation in beak size and shape over time
Which of the following statements describe the effect of evolution on a population?
increasingly better match between a population and its environment
It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that...
island forms are descended from mainland forms
What must be true of any organ described as vestigial?
it must be homologous to some feature in an ancestor
Which of these animals could overcome the geographic barrier of water that causes allopatric speciation?
it says mountain lions? i feel like it should be birds
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 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. If one builds a canal linking a predator-rich pond to a predator-poor pond, then what type of selection should subsequently be most expected among the mosquitofish in the original predator-rich pond, and what type should be most expected among the mosquitofish in the formerly predator-poor pond?
less-intense directional selection; more-intense directional selection
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
A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horse, 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
The higher the proportion of loci that are "fixed" in a population, the lower are that population's...
nucleotide variability and average heterozygosity
When Cuvier considered the fossils found in the vicinity of Paris, he concluded that the extinction of species...
occurs, but that there is no evolution
How can reproductive barriers form sympatric populations while their members remain in the same geographic area?
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
If individuals tend to mate within a subset of the population, there is...
random mating
The difference between geographic isolation and habitat differentation (isolation) is the...
relative location of two populations as speciation occurs
Which one of the following conditions would allow gene frequencies to change by chance?
small populations
According to the concept of punctuated equilibrium, the "sudden" appearance of a new species in the fossil record means that...
speciation occurred rapidly in geologic time
Which of Darwin's ideas had the strongest connection to his reading of Malthus's essay on human population growth?
struggle for existence
Among known plant species, which of these have been the two most commonly occurring phenomena leading to the origin of new species?
sympatric speciation and polyploidy
Whenever diploid populations are in Hardy-Weinberg equilibrium at a particular locus...
the allele's frequency should not change from one generation to the next
The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V-Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. In Darwin's tree of life, each fork in the tree represents...
the most recent common ancestor of the subsequent branches
A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait (aa) has not changed over time?
the two phenotypes are about equally adaptive under laboratory conditions
How is the length of time for speciation estimated?
time that elapses when populations of a newly formed species diverge
Which of the following statements describes mechanical isolation prezygotic barrier?
two species live in different habitats? (apparently two snails have shells that spiral in different directions is wrong?)
