Exam 18: Factors Influencing the Structure of Communities

The removal of a single species from a community can have unpredictable consequences.

When an indirect interaction is beneficial to one of two interacting species and neutral to the other,the indirect interaction is termed indirect ________.

Recent studies suggest that as species richness in a food web increases,the number of trophic links increases but the connectance decreases.

Competitive interactions are often diffuse,whereas mutualisms are not.

The "world is green" hypothesis suggests that herbivore populations limit the number of predators,allowing plant biomass to accumulate.

________ describes the number of trophic links in a food web.

Competition for belowground resources is considered to be asymmetric because larger plants have a disproportionate advantage in competition for those resources.

Patterns of temperature and ________ resulting from regional variations in climate are the major determinant of regional and global patterns of vegetation distribution.

The ________ is a group of plant and animal species that inhabits a given area.

The control of an herbivore population by a parasitoid is an example of top-down control.

The populations of keystone predators are controlled by the populations of their prey species.

When interspecific interactions involve more than just two species,they are said to be ________.

In aquatic communities,an increase in nutrients usually causes the number of autotrophic species to increase.

Plant community structure along an environmental gradient can often be explained by

In aquatic environments,the three major environmental gradients of water that directly influence the distribution and dynamics of communities include

Within a community,most species have a similar range of environmental tolerances.

The research of Sally Hacker has demonstrated that Juncus plants are strong antagonists,causing increases in conditions such as salinity that hinder the growth of other plants such as Iva.

________ or functional groups are groups of species in a community that are thought to have similar roles in the community.

A(n)________ model of community structure assumes that the presence and absence of individual species in a community result from independent responses to the physical environment,and interactions among species have no impact on community structure.

________ competition is a type of indirect interaction that occurs when a single species of predator feeds on two prey species.