ecology chp 16

estimates show that oceans absorb about______of all the atmospheric CO2

48%

trophic cascade

A change in the rate of consumption at one trophic level that results in a series of changes in species abundance or composition at lower trophic levels.

interaction web

A concept that describes both the trophic (vertical) and non-trophic (horizontal) interactions among the species in a traditional food web.

species accumulation curve

A graph that plots species richness as a function of the total number of individuals that have accumulated with each additional sample.

rank abundance curve

A graph that plots the proportional abundance of each species in a community relative to the others in rank order, from most abundant to least abundant.

interaction strength

A measure of the effect of one species (the interactor) on the abundance of another species (the target species).

foundation species

A species that has large, community-wide effects on the habitat or food of other species by virtue of its size or abundance.

ecosystem engineers

A species that influences its community by creating, modifying, or maintaining physical habitat for itself and other species.

functional group

A subset of a community that includes species that function in similar ways, but do not necessarily use the same resources.

trophic facilitation

An interaction in which a consumer is indirectly facilitated by a positive interaction between its prey or food plant and another species.

indirect interaction

An interaction in which the relationship between two species is mediated by a third (or more) species.

direct interaction

An interaction that occurs between two species, such as competition, exploitation, or a positive interaction.

redundant species

Having the same function in a community as other species in that community within a larger functional group.

Most food webs do not include information about symbiotic relationships.

In a competitive hierarchy, one species dominates the interaction; in an interaction network, no one species dominates the interaction.

Which statement best describes the difference between the theoretical concept of a community and the ways in which communities are delineated in practice?

In theory, communities consist of all species present; in practice, biologists usually study only a subset of the species.

Which statement describes a limitation of a species accumulation curve in terms of its ability to determine whether species diversity has been adequately sampled?

It assumes that the sampling methods are consistent throughout the study.

In their studies of a salt marsh community, Sally Hacker and colleagues found that removing _______ led to a(n) _______.

Juncus; decrease in the abundance of aphids through indirect effects

Which statement about food webs is true?

Most food webs do not include information about symbiotic relationships.

horizontal interactions

Non-trophic interactions, such as competition and some positive interactions, that occur within a trophic level.

competitive networks

Sets of competitive interactions involving multiple species in which every species negatively interacts with every other species, thus promoting species coexistence.

Which statement about the studies by Mary Power and colleagues on California rivers is true?

Species, such as the steelhead, that are keystone predators during normal years are minor players in the food web during drought years.

shannon index

The index most commonly used to describe species diversity quantitatively.

Which statement about keystone predators is true?

They usually influence primary producers indirectly.

food web

a diagram showing the connection between organisms and the food they consume

community

a group of interacting species that occur together at the same place and time

trophic level

a group of species that obtain energy in similar ways classified by the number of feeding steps by which the group is removed from primary producers, which are the first trophic level

species diversity

a measure that combines the number of species ( species richness) in a community and their relative abundances compared with one another (species evenness)

In the study by Jennifer Hughes and colleagues, in which community did it appear that the species richness had been adequately sampled?

a plant community from a forest in Michigan

guild

a subset of a community that includes species that use the same resource whether or not they are taxonomically related

An experiment by Alsterberg and colleagues showed that with ocean acidification and warming, the biomass of benthic microalgae

both a and b ( did not change with omnivores/ declined without omnivores)

Although beavers are relatively rare, they have considerable influence over species interactions in communities in which they are present because of the dams that they construct. The beaver is thus an example of a(n)

both b and c (ecosystem engineer/ keystone species)

Ecologists are concerned about the establishment of invasive species in new areas because invasive species

can have large ecological effects in their new communities

which conclusion was the primary finding of buss and Jackson's study of coral- associated invertebrates and algae in Jamaica?

competitive networks can be circular

Cougars prey on both white-tailed deer and mule deer. Because of their shared predator, each deer species' abundance is affected by the presence of the other deer species. The white-tailed and mule deer are engaged in a(n)

indirect interaction

what is the primary difference between interaction webs and food webs?

interaction webs include non-trophic interactions; food webs do not

Which statement about the "killer alga," Caulerpa taxifolia, is false?

it is toxic to humans and other mammals

Menge and colleagues performed experiments in which they exposed some populations of mussels to sea stars and excluded sea stars from other mussel populations. Suppose two populations of mussels are the same size prior to treatment, and after treatment there are 600 mussels in the treatment without sea stars and 200 mussels in the treatment with sea stars. Suppose further that the sea star population consists of 10 individuals. What is the per capita interaction strength of sea stars on mussels?

ln (0.33/10)

Members of the same functional group must belong to the same

none of the above

Species that feed on more than one trophic level are called

omnivores

Lions prey on animals such as zebras and wildebeest, which feed primarily on grasses. Lions thus should be considered

secondary consumers

the shannon index is a measure of

species diversity

Which value can be measured the most easily?

species richness

biodiversity

the diversity of important ecological entities that span multiple spatial scales, from genes to species to communities

species richness

the number of species in a community

species evenness

the relative abundances of different species compared to one another in a community

community structure

the set of characteristics that shape a community, including the number, compositions, and abundance of species