Exam 54: Community Ecology

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?

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. Which fact is correct when describing species interactions?

As you study two closely related predatory insect species, the two-spot and the three-spot avenger beetles, you notice that each species seeks prey at dawn in areas without the other species. However, where their ranges overlap, the two-spot avenger beetle hunts at night and the three-spot hunts in the morning. When you bring them into the laboratory and isolate the two different species, you discover that the offspring of both species are found to be nocturnal. You have discovered an example of ________.

The principle of competitive exclusion states that

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. During a one-year study, researchers found no difference in treehopper populations in any of their control and experimental groups. What could they measure during the second year to gain information about why this might have occurred?

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

Keystone predators can maintain species diversity in a community if they ________.

Use the graph to answer the following question. What does the graph tell you about the effect of a keystone species?

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?

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

Recall that Clements's view of biological communities is that of a highly predictable and interrelated structure, while Gleason's view of biological communities is that individual species operate independently. If we set up many identical sterilized ponds in the same area and allowed them to be colonized, what result should we expect Gleason had a more accurate view of communities than did Clement's hypothesis?