ECOLOGY TEST 3

Which of the following cannot be a resource for an organism?

Which statement about allelopathy is true?

Two species of birds actively fight over berries. Injuries have been observed, and the presence of one species limits the survival and reproduction of the other. What type of competition is this?

Numerous studies have supported that

Competitive exclusion states that two organisms cannot indefinitely occupy the same niche when resources are limited. When this does occur, organisms tend to show some sort of competitive coexistence. Which of the following is an example of competitive exclusion?

In bumblebees (Bombus) species that live together, they usually have different length proboscises that allow them to collect nectar from different flowers. This is an example of

Which observation would be the strongest evidence that character displacement is occurring?

Which of the following would most likely contribute to the long-term persistence of a fugitive species?

A bear accidentally carries the seeds of a weedy plant in its fur. Transporting the seeds neither helps nor harms the bear, but is beneficial to the plant. This is an example of a(n)

A wasp pollinating a plant in exchange for food is an example of

Spider crabs live on the ocean floor in shallow areas and greenish-brown algae live on their backs. This provides the algae with a home and the algae's greenish-brown color helps the crab blend in and stay safe from predators. This association can be considered a mutualism because

Most wasps are carnivores, but one group feeds on pollen and nectar and pollinates the flowers they visit. Wasps are less efficient than bees at pollination because their bodies are not covered with fuzzy hairs and therefore, pollen is less likely to stick to them. But masarine wasps specialize in pollinating certain species, including beardtongues (Penstemon sp.). Given this information, how will the costs and benefits of masarine wasp-plant mutualisms likely compare to those of bee-plant mutualisms?

Which species has been documented as imposing penalties on individuals of its mutualistic partner that are engaged in overexploitation?

A group of interacting species that occur together at the same place and time is known as a

Suppose you are wanting to study a tropical rainforest community. You choose to use a guild subset to study this community. Which of the following would be appropriate as this subset?

The lowest possible value of the Shannon index is _______ . Low values indicate species diversity. _______

Suppose you wanted to determine whether you had adequately sampled the species richness of a given amphibian community. Which result would most likely lead to the conclusion that more sampling was needed to assess the species richness?

Consider two tropical forests, each of which has 2,700 species. Both forests possess 2,500 of the same species, but 200 of the species are present in either one or the other tropical forest, but not both. This consideration is a measure of

The trophic facilitation phenomenon described by Hacker and colleagues involves direct interactions between two plant species in the form of _______, with indirect effects benefiting a(n) _______ of one of the plants.

Which scenario is a competitive network? Scenario I: Species 1 outcompetes species 2, which outcompetes species 3, which outcompetes species 4. Scenario II: Species 5 outcompetes species 6, which outcompetes species 7. Scenario III: Species 8 outcompetes species 9

Steelhead fish are predators of predatory insects, which in turn feed on midge larvae. The midge larvae feed on algae. By indirect effects, a reduction in the number of steelhead fish should lead to a(n) _______ in midges and a(n) _______ in algae.

Which statement about foundation species is true?

Despite having a relatively small biomass, populations of grizzly bears often have strong effects on their communities. The grizzly bear is therefore an example of a

Species that feed on more than one trophic level are called

Mushroom-feeding Drosophila species, including the species D. neotestacea, D. falleni, D. putrida, and D. recens, are prevalent in the Great Lakes region of the United States. Suppose a biologist collects flies from three different communities and obtains the results shown in the tables. What is the Shannon index of community 1?

Which statement about foundation species is true?

Despite having a relatively small biomass, populations of grizzly bears often have strong effects on their communities. The grizzly bear is therefore an example of a

Species that feed on more than one trophic level are called

A mudslide kills a large fraction of a population of a flower species. The reduction in this flower population allows for an increase in the population size of a fern that competes with the flower. This is an example of

What type of disturbance regime is most likely to result in gradual changes in community composition?

A forest community has reestablished itself after an ice storm damaged most, but not all, of the trees in one area. Which type of succession best describes the reestablishment of the community after the storm?

In a hypothetical example of succession, the early succession plants produce toxins that hinder both the subsequent colonization of other early succession species and colonization by later succession plants. This scenario fits the _______ model of succession

Suppose late succession plants that are surrounded by early succession plants grow at a rate of 0.7 cm per day. If the early succession plants are removed experimentally, the late succession plants are observed to grow at a rate of 0.6 cm per day. This experiment shows that the early succession plants have a _______ effect on the late succession plants, and this observation is most consistent with the _______ model of succession

A region that is experiencing very frequent disturbances of intermediate intensity will most likely exhibit _______ . If the intensity of these disturbances increases noticeably, the region will most likely exhibit _______

Which statement about regional scale is true?

Which of the following groups exhibits an atypical latitudinal species gradient?

Which statement about global biogeographic patterns is true?

Which statement comparing island biogeography to mainland biogeography is true?

Humans impact all of the factors that determine which species end up in a local community, including those that lead to the introduction of invasive species such as the zebra mussel (Dreissena polymorpha) in the Great Lakes. Which factor did humans most impact which led to the zebra mussel's invasion of the Great Lakes?

The algae Caulerpa taxifolia is native to warm tropical waters. However, a cold- tolerant strain was selectively bred for aquariums and as a result, it has become an invasive species in the Mediterranean where it grows in much colder water than its native range. Which of the following factors did humans have the greatest impact on?

The failure of some non-native species to become incorporated into communities is often attributed to _______ (i.e., the phenomenon whereby interactions with native species exclude or slow the growth of non-native species)

Which combination of attributes of a community should result in the lowest species richness?

Consider two species in competition for shared resources, species 1 and species 2. If these species are coexisting, which statement must be true?

Which of the following is not an assumption of a neutral model of species coexistence?

The ability of a community to remain the same in terms of its structure and function despite some perturbation is known as

Where would you be most likely to find abundant small evergreen shrubs with sclerophyllous leaves?

The fly species Drosophila santomea is found only on a single small island. Thus, this fly is considered to be

Which statement about New Zealand biogeography is true?

Which statement about species richness and composition is true?

Regional species diversity is also referred to as _______ diversity.

Suppose that multiple sites in a large geographic region have been found to have very similar species compositions of herbivorous insects, even though each site has a large number of species. These herbivorous insects are therefore said to have low _______ diversity.

In the figure, assume that the top line has a slope of 1 and the middle line a slope of 0.7. Which of the three relationships shown illustrates a scenario in which local processes most strongly limit species richness in a community?

A grassland region can be divided into several different local communities. For six different groups of butterflies (A–F), biologists have sampled the regional species diversity and the average local species diversity. Their results are presented in the table. Which conclusion can be made based on these data alone?

Which scientist conceptualized Earth as divided into six biogeographic regions and is considered the father of biogeography?

Kenya is located in the _______ biogeographic region.

Brazil is located in the _______ biogeographic region.

Which biogeographic region lies directly north of the Ethiopian biogeographic region?

Which biogeographical region is represented by X?

Which biogeographical region is represented by Y?

In some regions where two tectonic plates meet, one plate forces the other plate downward. Such areas are called

At the end of the Permian period (about 250 mya), Earth’s land masses

Which statement about the mammal fauna native to North and South America is true?

Suppose that a new river cuts through a land mass, separating populations of mice on either side. These mice then evolve into new species on the two sides of the land mass. This is an example of evolution by
a. continental drift.

Which of the following is not a common barrier to dispersal for organisms that live in the oceans?

Which group shows greater species richness in the temperate regions than in the tropics?

Which climatic zone has the greatest land area?

The table shows the number of species of a group of mammals present in the tropics, the subtropics, and the temperate zone over the last fifty million years. Of the three broad categories of hypotheses that have been proposed to explain latitudinal gradients (diversification rate, diversification time, and productivity or carrying capacity), these data most clearly fit which hypothesis?

The table shows the number of species of a group of mammals present in the tropics, the subtropics, and the temperate zone over the last fifty million years. Which specific hypothesis is best supported by the data in the table?

According to the study by Jablonski and colleagues, the majority of extant marine bivalve taxa originated in the

What is the meaning of the statement: “The tropics are a museum of species diversity”?

Which of the following hypotheses for the global latitudinal gradient in species is not supported by the figure?

Which of the following statements is most clearly supported by the data in the figure?

The figure shows the relationship between size of habitat and the number of mammalian species. According to the figure, we would expect a habitat that is 1,000 square kilometers to have _______ species of mammals.

The figure shows the relationship between size of habitat and the number of mammalian species. Based on the relationship between size and habitat, the area would have to increase approximately _______ times in order to support an additional five species.

The data shown in the figure were log-transformed before plotting. How would this plot look different if the original untransformed data were plotted instead?

The equilibrium theory of island biogeography was developed by

The equilibrium point for species diversity on a small island near the mainland would be represented by which letter?

The equilibrium point for species diversity on a large island near the mainland would be represented by which letter?

In accordance with Wilson and MacArthur’s theory of island biogeography, the following equations represent the immigration and extinction rates of species of beetles on a small island. (I = immigration rate of species per month; E = extinction rate of species per month; S = number of species currently on the island.)
I = 9 ‒ 0.2S
E = 0.3S
If there are 25 species on the island, the expected immigration rate is _______ species per month and the expected extinction rate is _______ species per month.

In accordance with Wilson and MacArthur’s theory of island biogeography, the following equations represent the immigration and extinction rates of species of beetles on a small island. (I = immigration rate of species per month; E = extinction rate of species per month; S = number of species currently on the island.)
I = 9 ‒ 0.2S
E = 0.3S
Based on these equations, what is the expected equilibrium species diversity on that island?

Which statement about the equilibrium model of island biogeography is false?

Which experimental manipulation was made on the island of Krakatau to test the equilibrium theory of island biogeography?

The figure shows bird species richness for islands of different sizes that are close to New Guinea, far from New Guinea, or intermediate in distance from New Guinea. Based on this figure, which of the following statements is false?

The figure shows bird species richness for islands of different sizes that are close to New Guinea, far from New Guinea, or intermediate in distance from New Guinea. Based on the figure, an island of around 2,600 km2 in area that is far from New Guinea has approximately how many bird species?

In their classic test of the equilibrium theory of island biogeography, Simberloff & Wilson removed arthropods from a set of small mangrove islands, then tracked the recovery of the arthropod fauna on these islands through time. Which of the following can be inferred from the figure?

In the equilibrium model of island biogeography, once an “island” has reached equilibrium,

Which of the following is a finding of the Biological Dynamics of Forest Fragments Project (BDFFP)?

Which statement about the Biological Dynamics of Forest Fragments Project (BDFFP) is true?

Fire-tolerant plant species in the Amazon are _______ abundant at the edges of forest fragments than inside the forest. The result is a _______ feedback loop and a(n) _______ in the effective size of the forest fragment.

Across various sites within the rainforest of Panama, different species of trees are found with little overlap among sites. Based on this pattern of species turnover, Panama’s rainforest is best described as having _______ diversity.

3. Witman’s studies of marine invertebrate communities demonstrated that in the systems studied

Which of the following is not a finding from the study on local and regional species richness by Witman et al. (2004)?

Which present-day continent was not part of Gondwana?

Which statement about plate tectonics is true?

The table shows the number of species of lizards present in the tropics, the subtropics, and the temperate zone over the last fifty million years. Of the three broad categories of hypotheses that have been proposed to explain latitudinal gradients (diversification rate, diversification time, and carrying capacity), these data best fit which hypothesis?

Which statement is closest to Alfred Russel Wallace’s early hypothesis for the higher diversity of life in the tropics?

Which position would best represent the equilibrium point for species diversity on a large island far from the mainland?

In accordance with Wilson and MacArthur’s theory of island biogeography, the following equations represent the extinction and immigration rates of species of spiders on a small island. (I = immigration rate of species per year; E = extinction rate of species per year; S = number of species currently on the island.)
I = 3 ‒ 0.1S
E = 0.2S
If there are five species on the island, the expected immigration rate is _______ species per year and the expected extinction rate is _______ species per year.

In accordance with Wilson and MacArthur’s theory of island biogeography, the following equations represent the extinction and immigration rates of species of spiders on a small island. (I = immigration rate of species per year; E = extinction rate of species per year; S = number of species currently on the island.)
I = 3 ‒ 0.1S
E = 0.2S
Based on these equations, what is the expected equilibrium species diversity on this island?

Which statement about Simberloff and Wilson’s test of the equilibrium theory of island biogeography using small mangrove islands in the Florida Keys is true?

Which statement about change in communities is true?

Which of the following is not an abiotic factor that can be an agent of change?

Which of the following is a biotic factor that can be an agent of change?

Which of the following would be considered a community stress?

The figure shows examples of possible disturbance intensity (y-axis) and frequency (x- axis) combinations. What type of disturbance would be likely represented by B?

The figure shows examples of possible disturbance intensity (y-axis) and frequency (x- axis) combinations. What type of succession occurs after the disturbance in A?

The figure shows examples of possible disturbance intensity (y-axis) and frequency (x- axis) combinations. What type of succession occurs after the disturbance in C?

The figure shows examples of possible disturbance intensity (y-axis) and frequency (x- axis) combinations. What type of succession occurs after the disturbance in D?

Which type of succession involves colonization of habitats devoid of life?

Which statement about early primary succession is false?

The final theoretical stage of succession is called the _______ stage.

Assume that the melting of a glacier is taking place at a constant rate of 50 meters per year, and that site A is 1.6 km farther from the ice edge than site B is. Based on this data, and the principle of “space for time substitution,” we can assume that the conditions seen at site A in the year 2011 are the same as those that _______ seen at site B in _______.

If Cowles is correct about succession, then

In the dunes near Lake Michigan studied by Cowles, the dominant plant species in the early stages of succession was

Which early ecologist maintained that plant communities are analogous to “superorganisms”?

Which statement best summarizes Elton’s views on succession?

Suppose that following a lava flow, pine grass (a hypothetical species) is the first species to colonize the area. Chemicals produced by pine grass change the soil chemistry in the environment, but these chemicals promote subsequent colonization by later species. Which model would best explain this scenario of succession?

The tolerance and the inhibition models of primary succession hold different assumptions about the

According to the _______ model of succession, the early successional species modify the environment so as to facilitate the subsequent colonization of other early colonizing species.

In their work on aspen–fir interactions, Calder and St. Clair claim that aspens are facilitated by the presence of fir trees. From these data, what is the primary evidence for aspen being facilitated by fir?

Suppose that a late succession plant that is surrounded by early succession plants grows at a rate of 0.5 cm per day. If the early succession plants are removed experimentally, the late succession plants are observed to grow at a rate of 0.9 cm per day. This experiment shows that the early succession plants have a _______ effect on the late succession plants, and this observation is most consistent with the _______ model of succession.

In his studies of succession in Glacier Bay, Chapin found that as communities went from early to latter stages of succession, soil moisture _______ and nitrogen _______.

In their studies of succession in Glacier Bay, Alaska, Chapin and colleagues found that the survival rate of germinated spruce seeds was highest at the _______ stage.

The studies by Chapin and colleagues on Glacier Bay succession provide empirical support for which model(s) of succession?

Chapin et al. conducted their work in Glacier Bay in 1994. If we were to return today to his plots, what could we predict to find in his former ten year-old pioneer communities that had been dominated by low shrubs, herbs, mosses, liverworts, and lichens?

At which stage of succession is facilitation usually the most significant factor?

In Farrell’s (1991) work on algal succession, the presence of limpets had what effect on the growth of algae?

Which statement about succession in the glaciers of Alaska is false?

You are in Glacier Bay. Starting at a location dominated by alders, you would most likely first run into the _______ stage if you travelled toward the glacier’s edge and the _______ stage if you travelled away from the glacier’s edge.

Which manipulation(s) did Bertness and Shumway perform in their studies of succession in a New England salt marsh?

In their manipulative studies of succession in a New England salt marsh, Bertness and Shumway altered salt stress in certain fields by

Bertness and Shumway’s studies of high salt stress conditions in the middle intertidal regions of New England salt marshes led to which conclusion?

Sousa’s studies of intertidal zones in southern California showed that

Farrell’s studies of algal succession on the Oregon coast showed that

The figure is derived from studies of algal succession in the presence and absence of the barnacle Balanus and limpets. Which condition is represented by the purple line (indicated by the black arrow)?

Alternative stable states most often arise

Which principle is best supported by the results of Sutherland’s studies in which fish predators were excluded from a marine fouling community?

Connell and Sousa criticized Sutherland’s experiments on alternative stable states in fouling communities on the grounds that

Suppose you are studying succession patterns in two species, species A and species B, both small aquatic organisms that colonize bare surfaces underwater. You replicated Sutherland’s experiments in this new system by placing bare tiles underwater in predator- protected areas and areas with predators. You collect data on the percent of cover for each species, as shown in the figure. Without predation, which species is a better competitor?

Suppose you are studying succession patterns in two species, species A and species B, both small aquatic organisms that colonize bare surfaces underwater. You replicated Sutherland’s experiments in this new system by placing bare tiles underwater in predator- protected areas and areas with predators. You collect data on the percent of cover for each species, as shown in the figure. Based on the data, what would you expect that a newly colonized area in a natural pond would look like?

Which human activity can bring about shifts in communities to alternative stable states?

. Plants with bacterial symbionts that fix _______ are often important players in _______ stages of succession.

Which statement about plants with nitrogen-fixing bacteria is true?

Which statement concerning Cowles’s early work on succession is false?

Assume that a glacier is melting at a constant rate of 50 meters per year and that site A is 1.6 km closer to the ice edge than site B is. Based on this data and the principle of “space for time substitution,” we can assume that the conditions seen at site A in 2011 are the same as those that _______ seen at site B in _______.

Suppose that you are in Glacier Bay, Alaska, and standing at a location that is dominated by Dryas. If you moved toward the edge of the glacier, you would most likely next encounter _______. If you moved in the opposite direction, away from the edge of the glacier, you would most likely next encounter _______.

Which statement about Bertness and Shumway’s studies of succession in a New England salt marsh is true?

Sousa’s studies of southern California boulders showed that algal succession is driven predominately by

Farrell’s studies of intertidal communities along the Oregon coast demonstrated that

Sutherland’s experiments showed that the capacity of the tunicate Styela to dominate communities depends primarily on

The inability of a system to shift back to the original community state, even after the original conditions have been restored, is called

The regime shift from kelp forests to urchin barrens along the west coast of the United States illustrates how human actions have caused communities to shift to alternate states. This particular shift was caused because of a decline in sea otters, most likely due to hunting. Why would the reintroduction or protection of sea otters not return the system to its original state?

Which statement best describes the difference between the theoretical concept of a community and the ways in which communities are delineated in practice?

Members of the same functional group must belong to the same

If a biologist wanted to study a hot spring community and were to sample the bacterial species causing its various colors, this would be an example of what type of subset?

Which value can be measured the most easily?

7. What is the primary difference between interaction webs and food webs?

8. Species that feed on more than one trophic level are called

Considering the food web, imagine a circumstance where a new, mutually beneficial relationship develops between H2 and H3, increasing both of their numbers. The effects of this on P2 and C2 are best described as

10. Lions prey on animals such as zebras and wildebeest, which feed primarily on grasses. Thus, lions should be considered

11. Which statement about food webs is true?

Which web(s) in the figure is(are) an interaction web?

Which species in the figure is an omnivore?

Which species in the figure is a primary producer?

According to the figure, species A is a(n)

How many total trophic levels are present in a food web in which the top trophic level consists of secondary consumers? (Do not consider decomposers or omnivores.)

The Shannon index is a measure of

Mushroom-feeding Drosophila species, including the species D. neotestacea, D. falleni, D. putrida, and D. recens, are prevalent in the Great Lakes region of the United States. Suppose a biologist collects flies from three different communities and obtains the results shown in the tables. Based on the Shannon index, rank the species diversity from highest to lowest.

Mushroom-feeding Drosophila species, including the species D. neotestacea, D. falleni, D. putrida, and D. recens, are prevalent in the Great Lakes region of the United States. Suppose a biologist collects flies from three different communities and obtains the results shown in the tables. What is the Shannon index of community 1?

Mushroom-feeding Drosophila species, including the species D. neotestacea, D. falleni, D. putrida, and D. recens, are prevalent in the Great Lakes region of the United States. Suppose a biologist collects flies from three different communities and obtains the results shown in the tables. If the four D. recens individuals in community 1 were replaced by four D. putrida, what would the Shannon index be?

What is the Shannon index value for an area in which only a single species is present?

Four species of fish in a pond are found in equal abundance. The Shannon index of the fish community is therefore

Suppose you wanted to determine whether you had adequately sampled the species richness of a given community. Which result would lead most strongly to the conclusion that the current sampling had adequately assessed the species diversity?

In the study by Jennifer Hughes and colleagues, in which community did it appear that the species richness had been adequately sampled?

Which statement describes a limitation of a species accumulation curve in terms of its ability to determine whether species diversity has been adequately sampled?

Which of the following example emphasizes the importance of species composition?

Cougars prey on both white-tailed deer and mule deer. Because of their shared predator, each deer’s species abundance is affected by the presence of the other deer species. The white-tailed and mule deer are engaged in a(n)

Cougars prey on both white-tailed deer and mule deer. Because of their shared predator, each deer’s species abundance is affected by the presence of the other deer species. The cougar and the mule deer are engaged in a(n)

Research has suggested that in some cases, killer whales (Orcinus orca) have increased their predation on sea otters. This would have a(n) _______ effect on kelp.

If another predator were to begin competing with sea otters for the urchins, they would have a(n) _______ effect on otters and a(n) _______ effect on urchins.

Considering the figure, which of the following scenarios would be best described as trophic facilitation?

The presence of a mutualist spider in a certain area improves the survival of an herbaceous shrub by reducing the impact of herbivorous insects. These spiders are preyed on by lizards, and lizards are eaten by birds. The removal of birds from the area would most likely have a(n) _______ effect on spiders and a(n) _______ effect on the plant.

In their studies of a salt marsh community, Sally Hacker and colleagues found that removing _______ led to a(n) _______.

Which statement about the difference between a competitive network and a competitive hierarchy is true?

Which conclusion was the primary finding of Buss and Jackson’s study of coral- associated invertebrates and algae in Jamaica?

Menge and colleagues performed experiments in which they exposed some populations of mussels to sea stars and excluded sea stars from other mussel populations. Suppose two populations of mussels are the same size prior to treatment, and after treatment there are 600 mussels in the treatment without sea stars and 200 mussels in the treatment with sea stars. Suppose further that the sea star population consists of 10 individuals. What is the per capita interaction strength of sea stars on mussels?

Suppose two populations of Anolis lizards are of equal size at the beginning of an experiment. One population (the experimental group) is exposed to a predator (16 predatory lizards), and the other (the control) is not. The final size of the experimental population is 50, and the final size of the control population is 200. What is the per capita interaction strength of predatory lizards on Anolis lizards?

When wolves were returned to Yellowstone National Park in 1995, some of the effects noted were increasing levels of berries available to black bears, stabilization of stream banks, increased nesting habitat for birds, and increasing beaver numbers as a result of rejuvenating aspen trees. These were later determined to be the results of reduced numbers and altered feeding behavior of elk as they were preyed upon by the wolves. Given this information, which of the following best describes wolves in Yellowstone National Park?

Where would a keystone species most likely be located in the figure?

Where would a foundation species most likely be located in the figure?

41. Which statement about keystone predators is true?

Which statement about the studies by Mary Power and colleagues on California rivers is true?

43. Estimates show that oceans absorb about _______ of all the atmospheric CO2.

Alsterberg and colleagues showed that with ocean acidification and warming, the biomass of benthic microalgae declined in the absence of omnivores. This was the result of increased negative interactions with its macroalgal competitors and herbivores. Given this information, the relationship between the omnivores and benthic microalgae can best be described as a(n) _______ interaction.

Which technique was used to determine the source of the alga Caulerpa taxifolia that invaded the coast of California?

The figure is of a species accumulation curve, based on the studies of Hughes and colleagues. The orange line (indicated by the black arrow) represents the species accumulation curve for which community in the study?

The studies by Power and colleagues of northern California river ecosystems
demonstrated

Menge and colleagues performed experiments in which they exposed some populations of mussels to sea stars and excluded sea stars from other mussel populations. Suppose that the sea star population consists of 20 individuals and the two populations of mussels are of the same size prior to the mussel treatment. In the treatment condition, there are 500 individuals without sea stars and 100 individuals with sea stars. What is the per capita interaction strength of sea stars on mussels?

Which statement about the seagrass Posidonia oceanica is false?

A bird species nests in a specific kind of tree. The tree is not harmed by the bird building its nest in the tree’s branches, but the bird benefits from the shelter provided by the tree and is better able to successfully raise young. This is an example of

In one interaction, a bird feeds on the seeds of a specific plant. Some of the seeds are digested, while others pass unharmed through its digestive tract and are deposited in new locations. In a second interaction, a bird digests all of the seeds from the plant and therefore, none of the seeds are dispersed. The plant is not damaged because the number of seeds eaten is relatively small. Which term best describes both of these interactions?

Three examples of associations in nature include: 1) Sea anemones riding on the backs of hermit crabs where the two species protect each other from their different enemies; 2) Lactobacillus bacteria living inside the human gut, having a beneficial effect on human health; and 3) Leaf-cutting ants farming and feeding on specific fungi, which receive free food and protection. How can these three associations best be classified?

Which criterion is most important in determining whether an ecological relationship is a symbiosis?

The loss of mycorrhizae-plant associations, in both angiosperms and gymnosperms, would have which effect on the plants?

A mycorrhizal-associated fungus grows between the cells of the root of a plant, forming a mantle around the exterior of the root. This is an example of which type of association?

Which statement describes the critical distinction between arbuscular mycorrhizae and ectomycorrhizae?

Algae called zooxanthellae live in the tissues of corals. Their photosynthesis provides organic compounds that the corals use as food and the corals provide the algae with a safe place to live and with nutrients to use in photosynthesis. This relationship is best described as

Cord grass is a major plant in saltmarshes in southeastern United States. It provides habitat for many saltmarsh species, such as snails, crabs, conch, and mullet. Within these species, cord grass could best be described as a

An ant colony maintains and farms a species of fungus on which it feeds. The fungus, in turn, is parasitized by a bacterium. The ant/fungus interaction is _______ and the fungusacterium is _______.

The table contains data on the effects of symbiosis between a fly (host) and a fungus over many years. It shows the upper and lower bounds for the effects of the association; positive numbers denote net benefits and negative numbers denote net costs. (If zero is between the upper and lower bounds, consider the effect to be zero, since it is statistically indistinguishable from zero.) According to the table, the relationship between the fungus and the fly in 1990 was a....

The table contains data on the effects of symbiosis between a fly (host) and a fungus over many years. It shows the upper and lower bounds for the effects of the association; positive numbers denote net benefits and negative numbers denote net costs. (If zero is between the upper and lower bounds, consider the effect to be zero, since it is statistically indistinguishable from zero.) According to the table, the relationship between the fungus and the fly in 1996 was a

The table contains data on the effects of symbiosis between a fly (host) and a fungus over many years. It shows the upper and lower bounds for the effects of the association; positive numbers denote net benefits and negative numbers denote net costs. (If zero is between the upper and lower bounds, consider the effect to be zero, since it is statistically indistinguishable from zero.) According to the table, in what year did the relationship between the fungus and the fly first become a mutualism?

Which factor in the association between figs and fig wasps, if true, indicates that they have gone and/or are undergoing coevolution?

In desert environments, many larger plants serve as “nurse” plants for smaller species that grow beneath them and benefit from their shade. Which characteristic of this association suggests that coevolution is not a major factor?

All other factors being equal, which scenario is least likely to involve coevolution?

The figure shows the influence of soil temperature on the interaction between two wetland plants, forget-me-nots and cattails. Cattails have extensive air channels for transporting oxygen in their leaves, stems, and roots. Forget-me-nots lack air channels. Based on the figure, as soil temperature increased, the influence of cattails on the growth of forget-me-nots changed from

The RNE (relative neighbor effect) measures growth of a target plant species in the presence and absence of neighboring species. The figure shows graphs of the RNE at eleven sites around the world. RNE was measured at high and at low elevations at each site. RNE values above zero (blue) indicate that neighboring plants increased the growth of target species; RNE values below zero (red) indicate that neighbors decreased target species growth. This study showed that the presence of neighboring plants most often benefited the target plants at

The RNE (relative neighbor effect) measures growth of a target plant species in the presence and absence of neighboring species. The figure shows graphs of the RNE at eleven sites around the world. RNE was measured at high and at low elevations at each site. RNE values above zero (blue) indicate that neighboring plants increased the growth of target species; RNE values below zero (red) indicate that neighbors decreased target species growth. What type of ecological interaction did plants show at high elevations and at low elevations, respectively?

The figure shows the RNE (relative neighbor effect) correlated to summer temperatures in alpine plants. Higher summer temperatures indicate communities at lower elevations, where plants are less stressed. The RNE is one measurement of the degree of mutualism in a community—the higher the RNE, the stronger the mutualistic interaction. Based on the data in this figure, which conclusion can be drawn about the importance of mutualism in this community?

A bacterium provides essential amino acids to an aphid, which in turn provides sugars to the bacterium. Assuming that each partner is benefiting from the interaction, this would be an example of which type of mutualism?

A fungus increases the ability of a plant to grow under high-salt conditions. For the plant, this association is which type of mutualism?

Because leaf-cutter ants and fungi help each other overcome plant defenses, the leaf- cutter ant–fungus mutualism can be described as which type of mutualism?

Which of these scenarios represents an example of habitat mutualism?

Medicago truncatula, or barrelclover, is a clover-like legume that has a mutualistic association with mycorrhizal fungi. In the experiment illustrated in the figure, fungi in contact with Medicago had access to either no phosphorus, or to either 35 or 700 μM of phosphorus. According to the figure, how did Medicago alter the amount of carbohydrate it transferred to the fungi in response to the change in fungal phosphorus levels?

In a plant-pollinator interaction, the plant expends energy to produce colors and scents that attract the pollinator. This energy is therefore not available to use in the plant’s growth and reproduction. This interaction provides evidence in favor of which statement?

For an ecological interaction to be a mutualism, the net benefits must

From the act of pollinating flowers, a bee population gains the benefit of a 0.06 growth rate increase per month. However, the costs imposed by the flower (bees occasionally getting stuck, time spent pollinating the flower instead of pollinating other species, etc.) is a 0.02 reduction in growth rate per month. The flower gains benefits from the pollination that enhance its population growth rate by 0.05 per month, but it incurs costs (feeding the bees, damage done by the bees) that reduce its growth rate by 0.05 per month. In this situation, what is the best description of the relationship between the bees and the flowers?

The studies by Pellmyr and Huth on yuccas and yucca moths showed that

Yucca plants retain 62% of the flowers that contain up to six moth eggs, but only 11% of the flowers containing nine or more eggs. The yucca aborts these flowers before the moth eggs hatch. This process is only effective for reducing exploitation by moths if

. An insect removes nectar from a flower without pollinating it. This is an example of a. the insect acting as a cheater.

The fruit fly Drosophila neotestacea carries a bacterial symbiont; the fly can also be infected by a nematode worm. The figure shows the number of eggs produced by female flies that are or are not infected by the nematode and that have or do not have the bacterial symbiont. Assuming that the nematode benefits by being inside the fly, the fly‒ nematode relationship, when there is no bacterial symbiont, is best described as a(n)

The fruit fly Drosophila neotestacea carries a bacterial symbiont; the fly can also be infected by a nematode worm. The figure shows the number of eggs produced by female flies that are or are not infected by the nematode and that have or do not have the bacterial symbiont. According to the figure, the bacterial symbiont

Acacia plants often have ants of the genus Pseudomymex associated with them. Removal of ant colonies from individuals of the bullhorn acacia species results in which change in the acacias?

When Daniel Janzen studied the ant–acacia system by removing ant colonies from some acacias, he found much lower growth rates in the acacia after ants were removed. Which other changes were seen in the responses of the acacia to ant removal?

What characteristics are found in Pseudomyrmex ants that depend on acacias, compared to species of Pseudomyrmex that are not associated with acacias?

In the study by van der Heijden and colleagues comparing the effects of differing numbers of mycorrhizal species (0–14) on the same 15 plant species, the shoot biomass of the target plants was found to

Which statement describes the most likely reason that a fish associated with a cleaner fish like Labroides dimidiatus does not eat the cleaner fish, even when the cleaner fish is in its mouth?

Grutter tested the effect of cleaner fish on species diversity in the Great Barrier Reef by

In a prairie ecosystem, mycorrhizal fungi form associations with the roots of prairie grasses, such as big bluestem. When the mycorrhizae are removed, the performance of big bluestem decreases, while the performance of other prairie grasses and wildflowers increases. This effect most clearly shows the influence of mutualisms on

In the study illustrated in the figure, van der Heijden and colleagues compared the effects of differing numbers of mycorrhizal species (0–14) on the same 15 plant species. They measured the effects of this mycorrhizal species diversity on net primary production (measured as shoot and root biomass) and on cycling of nutrients (measured as phosphorus content). Based on the figure, what can be concluded about the effect of mycorrhizal diversity on plant ecosystems?

Based on Grutter’s studies, we can conclude that the presence of cleaner fish

When leaf-cutter ants encounter the parasitic fungus Escovopsis, they

A seedling begins to grow very close to a leaf-cutter ant colony. What is a possible cost or benefit of growing in that area?

In the study by van der Heijden et al. of mycorrhizal fungi, the root biomass of the target plants (shown in the figure) was found to

What is the best description of the relationship identified by van der Heijden et al. between the average shoot biomass of the target plants and the number of mycorrhizal fungal species associated with them?

In Grutter’s studies in the Great Barrier Reef off of Australia, he measured the number of fish species and the number of individual fish on the parts of the reef where cleaner fish were present (controls) and where cleaner fish had been removed (experimental). Based on the figures, what is the best conclusion that can be drawn regarding the effects of cleaner fish on reef fish abundance and diversity?

In Daniel Janzen’s study of the ant–acacia association, which question was Janzen attempting to answer?

Scientists have studied the value of positive interactions in ecosystems by measuring the “relative neighbor effect” (RNE), or the effect that neighboring species have on the growth of a target species. Given the usual purposes of positive interactions, in which ecosystem would the neighboring plant species be most likely to help a target species?

Bromeliads and other tropical plants live in and on rainforest trees, obtaining food and living space from the trees but not helping or harming them. What type of association do trees and bromeliads have, and how much coevolution is occurring to maintain this relationship?

The table contains data on the effects of a symbiosis between a bee (host) and a bacterium over 22 years. The table shows the upper and lower bounds for the effects of the association; positive numbers denote net benefits and negative numbers denote net costs. (If zero is between the upper and lower bounds, consider the effect to be zero, since it is statistically indistinguishable from zero.) According to the table, this interaction first become a commensalism in