Why are the top predators in food chains most severely affected by pesticides such as

Currently, the number one cause of biodiversity loss is ______________.

According to the concept of competitive exclusion, a. two species cannot coexist in the same habitat. b. extinction or emigration is the only possible result of competitive interactions. c. intraspecific competition results in the success of the best-adapted individuals. d. two species cannot share the same niche in a community.

The concept of trophic structure emphasizes the a. prevalent form of vegetation. b. keystone species concept. c. feeding relationships within a community. d. species richness of the community.

Match each organism with its trophic level (you may choose a level more than once). a. alga b. grasshopper c. zooplankton d. eagle e. fungus 1. decomposer 2. producer 3. tertiary consumer 4. secondary consumer 5. primary consumer

Why are the top predators in food chains most severely affected by pesticides such as DDT?

Over a period of many years, grass grows on a sand dune, then shrubs grow, and then eventually trees grow. This is an example of ecological __________.

According to the pyramid of production, why is eating grain-fed beef a relatively inefficient means of obtaining the energy trapped by photosynthesis?

Local conditions, such as heavy rainfall or the removal of plants, may limit the amount of nitrogen, phosphorus, or calcium available to a particular terrestrial ecosystem, but the amount of carbon available to the ecosystem is seldom a problem. Why?

A __________ is a local grouping of interacting ecosystems with several adjacent habitats.

Movement corridors are a. strips or clumps of habitat that connect isolated fragments. b. landscapes that include several different ecosystems. c. edges or boundaries between ecosystems. d. buffer zones that protect the long-term viability of protected areas.

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. Then she enclosed one of the plots with a fence to keep out 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. Using the concepts discussed in the chapter, what do you think happened?

Imagine 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 the organisms you choose, creating an ecosystem that will support you and five other people for two years. Describe the main functions you expect the organisms to perform. List the types of organisms you would select, and explain why you chose them.

Interpreting Data In a classic study, John Teal measured energy flow in a salt marsh ecosystem. The table below shows some of his results. Form of energy Kcal/m2 /yr Efficiency of energy transfer (%) Sunlight 600,000 n/a Chemical energy in producers 6,585 Chemical energy in primary consumers 81 Data from: J. M. Teal, Energy Flow in the Salt Marsh Ecosystem of Georgia. Ecology 43: 61424 (1962). a. Calculate the efficiency of energy transfer by the producers. That is, what percentage of the energy in sunlight was converted into chemical energy and incorporated into plant biomass? b. Calculate the efficiency of energy transfer by the primary consumers. What percentage of the energy in plant biomass was incorporated into the bodies of the primary consumers? What became of the rest of the energy (see Figure 20.27)? c. How much energy is available for secondary consumers? Based on the efficiency of energy transfer by primary consumers, estimate how much energy will be available to tertiary consumers. d. Draw a pyramid of production for the producers, primary consumers, and secondary consumers for this ecosystem (see Figure 20.28).

Some organizations are starting to envision a sustainable societyone in which each generation inherits sufficient natural and economic resources and a relatively stable environment. The Worldwatch Institute, an environmental policy organization, estimates that we must reach sustainability by the year 2030 to avoid economic and environmental collapse. In what ways is our current system not sustainable? What might we do to work toward sustainability, and what are the major roadblocks to achieving it? How would your life be different in a sustainable society?

The Biological Dynamics of Forest Fragmentation Project, which has contributed so much to our understanding of threats to biodiversity, is itself endangered. Encouraged by Brazilian government agencies, urban sprawl and intensive forest settlement are closing in on the study site. Activities such as clear-cutting, burning, hunting, and logging threaten the integrity of the surrounding forest. Researchers at the BDFFP, which is jointly operated by a Brazilian research agency and the Smithsonian Tropical Research Institute, hope that they can bring attention to the problem through the Brazilian media and pressure the government into protecting the project. How would you argue the importance of protecting the BDFFP against ecologically destructive activities in a letter to a newspaper editor or to a government official?

Some scientists have argued that livestock production is the single greatest threat to biodiversity. What concepts that you learned about in this chapter might be used to support this contention?