Exam 56: Communities

A person studying a region's diversity at various levels, from genetic to species to community, is studying the region's _______.

A non-native fish species is accidentally introduced into a tropical river.It appears to be well adapted to its new river environment.However, it feeds on smaller fish and is less aggressive than native fish species, so it has difficulty competing and eventually dies out.This species' failure to become a member of the new community is due to which factor(s)?

An ecologist might subdivide a community on the basis of any of the following factors except

A single pitcher plant containing a group of interacting species and an entire forest, also filled with interacting species, both can be defined as _______.

During the eruption of Mount St.Helens, pocket gophers survived because they lived underground.After the eruption, their burrows were used by frogs and toads to move from pond to pond, which speeded up succession.This is an example of the process of _______.

Species cultivated for aquaculture can be set up so the byproducts or wastes of one crop (such as finfish or shrimp) are converted into fertilizer, food, and energy for the other crops, such as filter feeders (mussels) and algae.This process uses food, energy, and nutrients more efficiently by recycling them.This example shows the use of which practice to increase stability and productivity of the aquaculture system?

An animal species has the potential to become a member of a natural community forming in an area that is recovering from a massive hurricane.To become established in the new community, the first requirement is that the species must be able to

Ecologists found that, on Mount St.Helens, secondary succession proceeded much more rapidly than primary succession.What was one likely reason for this difference in time patterns?

Which situation would likely be considered a stress, rather than a disturbance?

A plant species is part of the regional species pool but fails to become established in a newly forming community.This failure to become established most likely occurs because

In an experiment in a Hawaiian forest, researchers removed all local birds from an enclosure.This resulted in an approximately 80-fold increase in the population of a non-native species of spider.This result suggests that the spider population was being limited by

Despite being so low in abundance that it is classified as a "near threatened" species, the jaguar plays an important role in structuring forest communities.It is thus considered a(n) _______ species.

A parasitic wasp preys on caterpillars, which in turn feed on leaves of cabbage and other garden plants.Because the parasitic wasps keep the caterpillar population low, the leaves of the garden plants are not damaged.This is an example of a(n) _______ interaction.

Beavers modify their habitat by building dams, which create wetlands, meadows, and ponds for themselves and other species.Humans also alter habitats, clearing forests and grasslands for agriculture and urban development.Beavers and humans can be considered both

The first limitation regarding which species can become members of a community is that they must be present in the regional _______ and be able to disperse into the new community.

The European green crab has become invasive in many places, including the Pacific Northwest.It is both carried in ships' ballast water and sold as fish bait.It becomes established during warm-water conditions like those that occur during El Niño years.The crab preys on many types of nearshore organisms, and its voracious appetite negatively affects the commercial shellfish industry.This information suggests that which factors enable the European green crab to become established?

A community that has only one species would have a Shannon diversity index (H) of

Refer to the graph, which is from Tilman's study on species diversity and community function in grassland ecosystems.It shows the change in efficiency of nitrogen use correlated with number of species in a community. Based on the graph, one can conclude that as species richness increases,

Wolves in Yellowstone National Park feed on elk, bison, and coyotes.When wolves were absent from the park, elk populations increased and browsed young aspen trees so much that they could not become established.The elk also browsed willows, which beavers required, and beavers disappeared from the area.When wolves were reintroduced into the park after many years of absence, elk declined, and aspen, willows, and beavers returned.This suggests that wolves in Yellowstone were responsible for

In what way is an invasive species most likely to harm the community it invades?