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Exam 54: Community Ecology

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Question 31

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Which of the following is a correct statement about MacArthur and Wilson's island equilibrium model?

A) As the number of species on an island increases, the emigration rate decreases.
B) Competitive exclusion is less likely on an island that has large numbers of species.
C) Small islands receive few new immigrant species.
D) Islands closer to the mainland have higher extinction rates.

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Question 32

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Red-cheeked salamanders are partially protected from predators because of cardiac glycosides they produce from glands on their back. When ingested, cardiac glycosides disrupt normal heart rhythms. A different salamander species, the imitator salamander, also has red cheek patches, but does not produce cardiac glycosides. It does gain protection from predators that have learned to avoid red-cheeked salamanders. How does this relationship affect the population dynamics of both species?

A) Both species are negatively affected.
B) Both species are positively affected.
C) The red-cheeked salamander is positively affected; the imitator is negatively affected.
D) The red-cheeked salamander is not affected; the imitator is positively affected.

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Question 33

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Food chains are sometimes short because

If two species are close competitors, and one species is experimentally removed from the community, the remaining species would be expected to ________.

Which of the following statements is consistent with the principle of competitive exclusion?

Use the following diagram of five islands formed at around the same time near a particular mainland, as well as MacArthur and Wilson's island equilibrium model principles to answer the question. Which region would likely have the greatest species diversity?

Use the figures to answer the following question. Connell conducted this experiment to learn more about ________.

Use the figure to answer the following question. Treehoppers (a type of insect) produce honeydew, which ants use for food. Treehoppers have a major predator, the jumping spider. Researchers hypothesized that the ants would protect the treehoppers from the spiders. In an experiment, researchers followed study plots with ants removed from the system and compared them to a control plot. From the figure, what can you conclude?

Use the following diagram of five islands formed at around the same time near a particular mainland, as well as MacArthur and Wilson's island equilibrium model principles to answer the question. Which island would likely have the lowest extinction rate?

How might an ecologist test whether a species is occupying all of its fundamental niche or only a portion of it?

Approximately how many kilograms (kg) of carnivore (secondary consumer) biomass can be supported by a field plot containing 1000 kg of plant material?

Use the figure to answer the following question. The figure proposes a combination of a top-down and bottom-up model (a hypothesis) to describe the variable effects of biological control herbivores on the fitness (growth and reproduction) of an invasive, non-native plant, spotted knapweed (Centaurea stoebe) . These herbivores include multiple insects that were first studied in the plant's native home range in eastern Europe, where the plant is not dominant in grassland communities and does not pose a problem to land managers and conservationists. Many insects there were found to consume the plant's tissues, including stems, leaves, and seeds, and some were very host specific and were not found to attack plants other than C. stoebe. Several insects were subsequently transported and released in an attempt to reduce densities of this non-native and problematic weed in the United States. The y-axis shows C. stoebe plant fitness, and the x-axis represents the intensity of herbivory by the insects, from low to high. As the vertical shaded bar is moved along the x-axis, the ultimate effect of herbivory (now A, B, and C) on plant fitness can change based on its intensity and also may depend on the other factors. The horizontal dashed line represents no predicted change in fitness under the effects of varying intensity of herbivory, plant competition, and soil resources available to the plant (such as nitrogen or water) , while the three solid lines represent other possible outcomes. (D) G. Knochel and T.R. Seastedt. 2011. Reconciling contradictory findings of herbivore impacts on spotted knapweed (Centaurea stoebe) growth and reproduction. Ecological Applications 20(7) :1903-1912. What is the model's prediction for C. stoebe plant fitness when growing under high soil resource conditions?

Which of the following is an example of aposematic coloration?

Which of the following measurements would be most helpful in understanding the structure of an ecological community? I. determining how many species are present overall II. determining which particular species are present III.determining the kinds of interactions that occur among individuals of the same species IV.determining the abundance of resources available for one species

Which of the following is an example of a commensalism?

The symbols +, -, and 0 are used to show the results of interactions between individuals and groups of individuals. The symbol + denotes a positive interaction, - denotes a negative interaction, and 0 denotes interactions in which individuals are not affected. The first symbol refers to the first organism mentioned. What interactions exist between a lion pride and African wild dogs, if the dogs are found to typically avoid areas with lions?

Which of the following is an example of Batesian mimicry?

Use the figure to answer the following question. In the figure, imagine that community 4 represents a marine community off the coast of Florida, where overfishing of a particular trophy fish (imagine a species G. for two decades gradually shifted it to resemble community 3. The species that was overfished was likely ________.

Use the following diagram of a hypothetical food web to answer the question. The arrows represent the transfer of energy between the various trophic levels. Which letter represents an organism that could be a producer?

Based on the intermediate disturbance hypothesis, a community's species diversity is increased by ________.