About a third of insect species measured are in decline, meaning that their populations are shrinking due to habitat destruction, pollution, and other factors. Predict how this change affects the bee pollination of crops such as apples and almonds.

The most plausible hypothesis to explain why species richness is higher in tropical than in temperate regions is thata. tropical communities are younger.b. tropical regions generally have more available water and higher levels of solar radiation.c. higher temperatures cause more rapid speciation.d. diversity increases as evapotranspiration decreases.

Draw a vertical food chain (part of a food web) showing that sea urchins eat kelp and that sea otters eat sea urchins. Use this model to (1) show or explain how a trophic cascade works; and (2)offer an explanation for why otters are considered a keystone species.

Community 1 contains 100 individuals distributed among four species: 5A, 5B, 85C, and 5D. Community 2 contains 100 individuals distributed among three species: 30A, 40B, and 30C. Calculate the Shannon diversity (H) for each community. Which community is more diverse?

In Southeast Asia, there's an old saying: 'There is only one tiger to a hill.' In terms of energy flow in ecosystems, explain why big predatory animals such as tigers and sharks are relatively rare.

Suppose that a two-acre lawn on your college's campus is allowed to undergo succession. Describe how species traits, species interactions, and the site's history might affect the community that develops.

There are fewer lions in Africa's Serengeti than there are zebras. This is principally because .a. zebras tend to drive off lions;b. lions compete directly with cheetahs, whereas zebras do not have any competitors;c. zebras have mutualists that increase their population, whereas lions do not;d. there is less energy available in zebras to support the lion population than there is in grass to support the zebras;e. zebras are a keystone species, whereas lions are not

A team of 102 scientists spent a year surveying a small area of the San Lorenzo rain forest in Panama to count the number of species of arthropods living there. After collecting 129,494 specimens—using nets, traps, shovels, tree-climbing harnesses, helium balloons, and other creative gear—it took the team eight years to sort and identify the arthropods.Rather than measuring the entire 6000-hectare (ha) forest, the researchers sampled arthropod diversity by intensively collecting as many arthropods as they could in 12 plots that measured 20m×20msquare. If 1ha=10,000m2,, how many hectares of forest did they sample in all?a. 20m×20m×12=4800hab. 4800m2×10,000m2/1ha=48,000,000hac. 20m×20m=400had. 4800 m^2 x 1ha/10,000 m^2 = 0.48 ha

SCIENTIFIC THINKING An ecologist studying plants in the desert performed the following experiment. She staked out two identical plots, which included a few sagebrush plants and numerous small, annual wildflowers. She found the same five wildflower species in roughly equal numbers on both plots. She then enclosed one of the plots with a fence to keep out kangaroo rats, the most common grain-­eaters of the area. After two years, to her surprise, four of the wildflower species were no longer present in the fenced plot, but one species had increased dramatically. The control plot had not changed. Using the principles of ecology, propose a hypothesis to explain her results. What additional evidence would support your hypothesis?