Ecology Ch 17

Identify which of the following interactions would be classified as only being direct interactions. Also, identify which of the following interactions have an indirect component to them. 1. direct interactions 2. indirect interactions A. acacia ants protect the acacia tree from herbivores B. cougars preying upon cotton-tailed rabbits C. a beaver constructs a dam creating a new pond ecosystem D. the lions kill multiple gazelles which results in an increase in the grass population E. a parasitoid wasp attacks the caterpillars that were feeding upon a farmers crop F. blue jays eating acorns produced by white oak trees.

1. A, B, F 2. C, D, E

Match the research approaches and information obtained to the particular research project. 1. ants 2. cleaner wrasses A. their population was reduced by a competing invasive species B. were experimentally removed from the community to determine their importance C. they play a critical role in sustaining the producer base D. when experimentally introduced to new areas, the community diversity increased E. species richness decreased by 24 % when removed and increased by 24 % when introduced

1. A, C 2. B, D, E

Identify the pros and cons of emphasizing strong interactions in food web studies 1. pros 2. cons A. determines the degree of community structure B. is not a measure of the quantity of energy flow C. focused only on the strongest feeding relationships D. emphasizes the more biologically significant trophic interactions

1. A, D 2. B, C

Match the correct organisms with their respective feeding level in the Antarctic pelagic food web. 1. diatom 2. squid 3. krill 4. emperor penguin 5. killer whale 6. leopard seal A. level 3 B. level 6 C. level 2 D. level 1 E. level 5 F. level 4

1. D 2. A 3. C 4. F 5. B 6. E

The feeding activities of a keystone species may control the structure of communities. Paine (1966, 1969) proposed that keystone species affect community structure in specific directions. Complete each sentence with the correct term describing his research. 1. Paine predicted that some predators may _____ species diversity in intertidal communities 2. this outcome is predicted because some predators _____ the probability of competitive exclusion by lower trophic levels increase reduce

1. increase 2. reduce

Identify the potential consequences of removing Cyanistes caeruleus from the ecosystem. check all that apply: A. There would be a corresponding decrease in the Aprostocetus calamarius population. B. There would be minimal change in the Aprostocetus gratus populations. C. The Phragmites australis population would suffer an increase in predation. D. There would be a significant decrease in the Aprostocetus gratus populations.

A, B, C

Identify the results obtained by Orrock, Witter, and Reichman that support their hypothesis that the relationship between Brassica nigra and Nassella pulchura is apparent competition. check all that apply A. The distribution pattern between Brassica nigra and Nassella pulchura suggest competition. B. N. pulchra suppresses B. nigra sheltering mammalian herbivores that feed on the native grass. C. Both B.nigra and N. pulchra support large populations of mammalian herbivores that feed on the native grass. D. B. nigra actually suppresses N. pulchra indirectly by sheltering mammalian herbivores that feed on the native grass.

A, D

In a mangrove forest in Central America, mangrove trees were found to contain between 60-85% of the total above-ground biomass. How would you categorize mangrove trees in this ecosystem? A. a foundation species B. a keystone species C. both a foundation and a keystone species D. neither a foundation nor a keystone species

A. a foundation species

A keystone species is best defined as A. species that, despite low biomass, exert strong effects on the structure of the communities they inhabit. B. rare species with a low proportion of the biomass in the community C. species that represent a dominant proportion of the biomass and exert strong effects on the structure of the communities they inhabit. D. species that, in a successional sequence of communities, establish immediately following a disturbance.

A. species that, despite low biomass, exert strong effects on the structure of the communities they inhabit.

Identify the statement that best describes the key difference between a keystone species and a foundation species. A. Foundation species are always top level predators. B. Keystone species have a low level of biomass within the community while foundation species have a high level of biomass. C. Keystone species are always omnivores while foundation species are always producers. D. Keystone species have a high level of biomass within the community while foundation species have a low level of biomass.

B. Keystone species have a low level of biomass within the community while foundation species have a high level of biomass.

Martinsen, Driebe, and Whitham provided evidence for __________ with beaver consumption of cottonwoods resulting in higher densities of herbivorous beetles. A. indirect keystone predation B. indirect commensalism C. apparent competition D. keystone predation E. indirect competition

B. indirect commensalism

Identify the components used by Robert Paine to formulate and support his keystone species concept. keystone species concept: A. competitive exclusion would be high in populations that are below their carrying capacity B. competitive exclusion would be low in populations that are below their carrying capacity C. predators can keep their prey population below the carrying capacity D. keystone species would increase the species diversity within communities through their actions E. predator populations will always have a high biomass

B, C, D

A foundation species is best defined as A. organisms, such as mountain lions and coyotes, that substantially influence community structure through predation. B. organisms, such as abundant, forest tree species or coral reef species, that substantially influence community structure as a consequence of their abundance. C. a group of a few organisms in a community that do not have a large influence on community structure. D. organisms classified as mutualists, such as cleaner fish, that clean other fish of ectoparasites.

B. organisms, such as abundant, forest tree species or coral reef species, that substantially influence community structure as a consequence of their abundance.

In Jane Lubchenco's tidepool system, removal of the herbivorous snail Littorina led to A. dominance of the tidepools by the unpalatable alga Chondrus. B. replacement of Chondrus by the more palatable alga Enteromorpha. C. replacement of Chondrus by other algae better adapted to herbivory. D. replacement of Enteromorpha by other algae that are better competitors. E. no marked change in the algal community.

B. replacement of Chondrus by the more palatable alga Enteromorpha.

In zooplankton and intertidal communities, as the overall diversity of the food web increases, the proportion of predators in the web A. tends to decrease B. tends to increase C. first decreases, then increases again D. first increases, then decreases again E. stays about the same

B. tends to increase

Cleaner wrasse are mutualists of other coral reef fishes. What benefit do they provide to those other fish? A. They suppress diseases because they consume carcasses of dead fish. B. They keep water oxygenated because they consume organic debris before it can rot. C. They keep fish relatively free of externally feeding parasites. D. They maintain fish habitat by keeping corals free of encrusting algae. E. They reduce fish mortality by repelling large vertebrate predators.

C. They keep fish relatively free of externally feeding parasites.

Human hunters in the Amazon rain forests kill A. large numbers of almost every mammal and bird species, for food and for skins. B. large numbers of the smallest mammal and bird species, which are easiest to catch. C. large numbers primarily of the largest mammal and bird species. D. large numbers of mammals and birds, but do not greatly affect population densities. E. only a few mammals and birds, but because humans are keystone species, these few kills greatly reduce population densities.

C. large numbers primarily of the largest mammal and bird species.

The cleaner wrasse fish and seed dispersal ants are examples of what ecological concept? A. Predators can be used for pest control. B. Indirect commensalism. C. Dominant species of a food web. D. Mutualists can be keystone species. E. Apparent competition.

D. Mutualists can be keystone species.

Teja Tscharntke simplified the food web associated with the wetland reed Phragmites australis by dividing the species into which of the following major trophic levels? A. plant, herbivore, piscivore, granivore B. herbivore, carnivore detritivore, consumer C. herbivore, parasite, carnivore, detritivore D. plant, herbivore, parasite, carnivore E. plant, detritivore, parasite, herbivore

D. plant, herbivore, parasite, carnivore

In Robert Paine's studies of the Washington intertidal community, which organism proved to be a keystone species? A. the whelk thais B. acorn barnacles C. chitons D. the starfish Pisaster E. limpets

D. the starfish Pisaster

a keystone species is one A. that makes up a very large proportion of total community biomass. B. that feeds on a very large fraction of all available prey species. C. that is fed on by a very large fraction of all predators in its community. D. whose feeding activities have a disproportionate effect on the structure of its community. E. that occupies the lowest level (the base) of the food web.

D. whose feeding activities have a disproportionate effect on the structure of its community.

Based on studies by Jane Lubchenco, what influence does the population density of the herbivorous intertidal snail, Littorina littorea, have on the number of algal species? A. As snail density increases from low to medium, the number of algal species increases. B. As snail density increases from medium to high, the number of algal species increases. C. As snail density increases from low to medium, the number of algal species decreases. D. As snail density increases from medium to high, the number of algal species decreases. E. Both as snail density increases from low to medium, the number of algal species increases and as snail density increases from medium to high, the number of algal species decreases.

E. Both as snail density increases from low to medium, the number of algal species increases and as snail density increases from medium to high, the number of algal species decreases.

A predator and its prey interact __________, but if the predator affects another species through this interaction, ecologists describe it as a(n) __________ interaction A. strongly; inefficient B. directly; variable C. weakly; diffuse D. indirectly; keystone E. directly; indirect

E. directly; indirect

Teja Tscharntke's studies of the food web associated with Phragmites reeds revealed that A. only a single parasitoid species can persist exploiting a single species of herbivore. B. only a single herbivore species can persist attacking a single species of plant. C. predation by birds actually protects herbivores, because the birds feed on parasitoid-infested herbivore galls but not uninfested galls. D. within local food webs, all interactions tend to be of roughly the same strength. E. recognizing variation in interaction strength can greatly simplify the depiction of a food web.

E. recognizing variation in interaction strength can greatly simplify the depiction of a food web.

T/F: The impact of Argentine ants on species diversity in the South African fynbos is most dramatic following fires.

true

T/F: The presence of cleaner wrasse enhances diversity of fishes on coral reefs.

true

Ecologists summarize feeding interactions among species in a community when they compile a __________.

food web