Ecology Ch. 17

In conducting a study of trophic relationships in a stream community, you record the following data for the six species you observed. Which species would most likely be the foundation species for this community? E

Species	Number Observed	Total Biomass (kg)
A	103	192
B	231	94
C	87	132
D	435	234
E	78	257
F	31	71

In the following, simplified food chain, which pairs of species have indirect interactions?

Sp. A >> Sp. B >> Sp. C >> Sp. D

Sp. B and Sp. D; Sp. A and Sp. C

Rank the snail density conditions in order of increasing algal species richness. In other words, which snail densities produced lowest, middle and highest algal richness.

High snail density >> low snail density >> middle snail density

In Power’s experiments, she was trying to determine whether trout and roach were acting as keystone species

A keystone species would be considered to be a type of foundation species

By burying seeds, ants help plants avoid which of the following sources of mortality?

Rodents, fires

Apparent competition is a type of indirect interaction

In representing the communities in Cano Volcan, one approach used by Winemuller was to exclude the most common species

In a commensal relationship between two species, one species is benefited while there is neither harm nor benefit to the other

Which of following interactions are considered to be strong interactions in Tscharntke’s food web of a Phragmites community? Phragmites-G.inclusa; T.arundinis-C.caerulus; Phragmites-A.geminipuncta

Which three of the following factors did Lubchenco propose to be necessary in order to resolve the conflicting results of herbivore – diversity experiments? Herbivore food preference; location-based changes in competition and food preferences; local competitive relationships

In addition to feeding on invertebrates, the roach (fish) will also eat algae

Food webs are used to represent feeding relations within a community

In environments where Littorina’s feeding preferences is the competitively inferior alga taxa, rank the density conditions in order of increasing algal species richness with the lowest at the bottom. In other words, which snail densities produce the lowest, middle and highest algal richness? Low snail densities >> middle snail densities >> high snail densities

The activities of cleaner fish are considered to be an example of mutualism

In his research in Mukkaw Bay on the role of predators in community diversity, the control treatments for the experiment received no predators

A disease wipes out most of the trout in the Eel River. Which of the following populations would you expect to increase as a result of this? Predatory insects; roach fry; Cladophora

Stem-boring by larvae of A.geminipuncta are responsible for inducing Phragmites to produce side branches

The purpose of the exclosure cages in Power’s experiments was to exclude Steelhead trout from the study plots

Indirect interactions between two species requires an intermediate species

Which of the following trophic interactions were observed in the Phragmites community studied by Tscharntke? Arrows indicate the direction of energy flow, eg. A >> B, indicates that A is eaten by B

Phragmites >> fly (G.inclusa); fly (G.inclusa) >> Blue Tits; Phragmites >> moth (A.geminipuncta)

In representing the communities in Cano Volcan, one approach used by Winemuller was to exclude the weakest trophic links

Predators that keep prey populations below their carrying capacity and prevent competitive exclusion by one of these species are known as keystone species

Algal species richness was greatest at which snail density? Middle

Lubchenco’s research on the relationship between herbivores and community diversity was motivated by conflicting results in previous experiments. TRUE

Species that have a substantial influence on community structure due to their high biomass are referred to as foundation species

In the tide pools in which Lubchenco removed snails, the abundance of the alga Enteromorpha increased, while the alga Chondrus decreased relative to the control treatment.

Experimental removal of cleaner wrasses from reef patches by Bshary resulted in a decrease in the number of fish species on the patch

Lubchenco conducted the feeding preference experiments with snails in the laboratory

The purpose of the control treatment, in the experiment by Orrock et al., was to account for disturbance effects

A disease wipes out most of the trout in the Eel River. Which of the following populations would you expect to increase as a result of this? Roach fry; predatory insects; Cladophora

In the intertidal food web of Mukkaw Bay, a seastar is considered to be the top predator

Weaver ants obtain liquids and carbohydrates from mealy bugs

Yang found that the weaver ants did not attack parasites of the mealy bugs

In response to the removal of starfish, the space occupied by the barnacle Balanus increased

Redford has proposed that human hunting has undermined the role of keystone species maintaining diversity in rain forest communities

The ability of the predaceous fire ant to act as a keystone species in arthropod communities is a benefit for corn and squash farmers

The sprouts growing from trees felled by beaver have leaves that are more nutritious for the beetles than those growing on mature trees

After a local population explosion of sea gulls, you would expect to find an increase in abundance of the alga Chondrus in the tide pools

In the intertidal food web of the Gulf of California there are a total of 11 predators in the system

Lubchenco studied the relationship between algal abundance and snail densities in tide pools

Bshary observed the number of fish species on reef patches and the presence or absence of cleaner wrasses

The most influential trophic relationships in a food web are known as strong interactions

Removal of predatory fire ants from corn and squash fields would likely lead to an increase in crop damage from insect pests

Which one of the following would best represent food web control on the population of the snail Littorina? Snail >> crab >> seagull

Lubchenco conducted the snail removal experiments in tide pools

Yang found that the weaver ants function as a keystone species in orange trees by feeding on larger insects

In defining “strong interactions”, Paine felt that the most important factor in defining community structure was the degree of influence, but not the energy flow of interactions

Which of the following represents the indirect commensalism observed by Martinsen et al.?

Beaver – cottonwood – beetle

In feeding preference experiments with snails, Lubchenco found that small tender algae were generally preferred over those that are tough and perennial

In the intertidal food web of the Gulf of California, a seastar is considered to be the top level predator

The weaver ants have a mutualistic relationship with mealy bugs – the ants receive fluids and carbohydrates while the mealy bugs benefit from protection from predators

Redford considers species that have had their densities reduced to the point that they can no longer function as keystone species as ecologically extinct

In Power’s study of stream communities, trout performed a similar function as a keystone species to the snails in Lubchenco’s experiments in tide pools

In Lubchenco’s study of tide pools, the snail Littorina performed a similar function to the Pisaster in Paine’s Mukkaw Bay experiments – controlling the populations of the dominant space competitor

Littorina’s preference for feeding on the competitively dominant alga could produce the pattern of algal richness seen by Lubchenco

In his New Zealand experiments, Paine found that removal of a sea star resulted in an increase the area occupied by a mussel

Paine concluded that greater numbers of predators in a community produces increased predation pressure, leading to an increase in diversity of the community

In looking at the communities on islands created by a dam impoundment that excluded large predators, Terbough observed changes to community structure that were so large that he described them as an ecological meltdown

Removal of the seaweed Durvillea enhanced the effects of only removing the seastar from the intertidal zone in New Zealand

Consistent with their hypothesis that about apparent competition between mustard and bunch grass, Orrock et al. found bunch grass did better when rodents were excluded

Lubchenco’s research supported that of Paine, showing that a single species could control the diversity of a community

Paine found that as the number of species in a food web increased, there was an increase in the number of predators in the community

At high densities, Littorina needed to switch to feeding on less preferred alga species in order to meet their energy needs

In looking at the role of large predators, Terbough found that medium-sized mammals are more abundant when the predators are absent

Paine also conducted a series of experiments that removed the seaweed Durvillea, which is also an important space competitor

As a result of their experiments, Orrock et al. proposed that the rodents use mustard for protective cover, feeding on the bunch grass