Exam 56: Communities

Gopher tortoises are native to the southeastern United States.Which characteristic of gopher tortoises would best support the claim that they act as both keystone and ecosystem engineering species in their communities?

In a desert food web, cacti are eaten by flies.Flies are eaten by scorpions, which are eaten by roadrunners.In this food web, the primary consumers are the _______.

The regional species pool of a community defines the conditions for a species to

The stomach contents of a mammal are examined and found to contain the remains of mice, birds, insects, worms, snails, berries, seeds, grass, and leaves.This organism is therefore a(n)

What factor can best be used to distinguish a disturbance from a stress in a community?

Refer to the figure. In which list are organisms ordered correctly from lowest to highest trophic level, according to the figure?

The golden toad of Central America is thought to be extinct in the wild.The mountaintop cloud forests in which it lived no longer exist, because of drought and other changes associated with climate change.In this case, it appears that changing environmental conditions affected the habitat of the golden toad by

As a community develops, more species enter the community and become established.How will this affect the Shannon index (H) of the community?

Following a severe ice storm, the composition of the trees changed in a community as it recovered from the disturbance.This is an example of _______ succession.

Which of these organisms is a primary producer?

In comparing the terms "species diversity" and "biodiversity," it would be most correct to say that

Refer to the graph, showing the interaction between the elk population and the presence or absence of wolves in Yellowstone National Park. Elk culling (hunting by humans) occurred until 1968.Based on this information, what factor had the most influence on the population of elk between 1926 and 1968?

A tropical rainforest is home to hundreds of species of trees that overlap in their resource requirements.Assuming multiple tree species have similar rates of population growth and similar access to the space and resources available, rainforest trees can be said to work in accordance with a neutral, or _______, model in maintaining species diversity.

Removal of a keystone species from a community will likely decrease species richness by interrupting

Students comparing insect communities in two fields find that both fields have ten species of insects.However, field A has mostly grasshoppers of a single species; the other nine species are rarely seen.Field B, in contrast, has approximately equal numbers of all ten species.This finding shows a difference in species diversity in the fields, which is due to a difference in species _______.

A gardener plants a bed that contains several blueberry bushes, several red clover and yarrow plants, and 100 strawberry plants.The strawberries provide a ground cover that conserves moisture and suppresses weeds.The red clover provides nitrogen, and the yarrow provides other nutrients for the blueberries.Because of its multiple species and their interactions, this bed can be considered a _______.

Area A has 50 species.One species is very dominant, making up 90 percent of the total biomass, while the others are very rare.Area B has only 20 species, but they are distributed so that all are present in relatively equal numbers.Compared with area B, area A has a very high level of _______.

Using examples, compare the stability of monocultures with that of polycultures, and explain why their stabilities are different.How have scientists learned about this difference in stability?

Two fish species live and compete on a coral reef.Fish A is dominant and maintains a larger population than fish B.During a very hot summer, a temperature spike occurs on the reef, killing off most of fish A's population.The fish B population then begins to increase.This scenario describes the process of

Zones created by the eruption of Mount St.Helens included the Pumice Plain nearest the lava dome, the Blowdown Zone along the mountain slopes, and beyond those, forests covered with debris and ash.Which, if any, of these zones would be the fastest to begin recovering living communities, and why?