Exam 54: Community Ecology

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

Which of the following is the most accepted hypothesis as to why invasive species take over communities into which they have been introduced?

Elephants are not the most dominant species in African grasslands, yet they influence community structure. The grasslands contain scattered woody plants, but they are kept in check by the uprooting activities of the elephants. Take away the elephants, and the grasslands convert to forests or to shrublands. The newly growing forests support fewer species than the previous grasslands. Which of the following describes why elephants are the keystone species in this scenario?

Monarch butterflies are protected from birds and other predators because of cardiac glycosides they incorporate into their tissues from eating milkweed when they were in their caterpillar stage. The wings of a different species of butterfly, the Viceroy, look nearly identical to the Monarch so predators that have learned not to eat the bad-tasting Monarch avoid Viceroys as well. This example best describes

The next series of questions presumes that you have at least once visited and have some knowledge of the fast-food restaurant McDonald's. Use your knowledge of McDonald's and your understanding of community ecology to answer the following questions about an ecological community, McDonaldland. -Which two "species" are likely to compete for the same ecological niche?

Dwarf mistletoes are flowering plants that grow on certain forest trees. They obtain nutrients and water from the vascular tissues of the trees. The trees derive no known benefits from the dwarf mistletoes. Which of the following best describes the interactions between dwarf mistletoes and trees?

Why are food chains relatively short?

In a particular case of secondary succession, three species of wild grass all invaded a field. By the second season, a single species dominated the field. A possible factor in this secondary succession was

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

Which of the following could qualify as a top-down control on a grassland community?

Primary succession differs from secondary succession in what way?

Which of the following statements does not describe a zoonotic pathogen?

The energetic hypothesis and dynamic stability hypothesis are ideas that attempt to explain

The feeding relationships among the species in a community determine the community's

Which statement best describes the evolutionary significance of mutualism?

Why do moderate levels of disturbance result in an increase in community diversity?

Imagine five forest communities, each with 100 individuals distributed among four different tree species (W, X, Y, and Z). Which forest community would be most diverse?

Food chains are sometimes short because

Approximately how many kg of carnivore biomass can be supported by a field plot containing 1000 kg of plant material?

The oak tree pathogen, Phytophthora ramorum, has migrated 650 km in 10 years. West Nile virus spread from New York State to 46 other states in 5 years. The difference in the rate of spread is probably related to