Q. A. An ecologist studying desert plants performed the following experiment. She staked out two identical plots that included a few sagebrush plants and numerous small annual wildflowers. She found the same five wildflower species in similar numbers in both plots. The she enclosed one of the plots with a fence to maintain kangaroo rats, the most common herbivores in the area. After two years, four species of wildflowers were no longer present in the fenced plot, but one wildflower species had increased dramatically. The unfenced control plot had not changed significantly in species composition. By means of the concepts discussed in the chapter, what do you think happened?

B. supposes that you have been chosen as the biologist for the design team implementing a self-contained space station to be assembled in orbit. It will be stocked with organisms you choose, creating an ecosystem that will support you and five other people for two years. Explain the main functions that you expect organisms to perform. List the types of organisms you would select, and explain why you chose them.