Chapter 17 Species Interactions and Community Structure Flashcards
In food webs, a feeding relationship is represented as a(n) ______ connecting two ______.
line; organisms
In representing the communities in Caño Volcán, one approach used by Winemiller was to _______ the most rare species.
exclude
In defining “strong interactions” in food webs, Paine felt that the most important factor in defining community structure was the ______, but not the ______ of interactions.
degree of influence; energy flow
Species that have a substantial influence on community structure due to their high biomass are referred to as ______ species
foundation
True or false: Blue Tits feed on larvae of the moth, A. geminipuncta.
False
They feed on the galls formed by G. inclusa thus forming a species interaction.
Food webs are ______.
used to represent feeding relations within a community
Which of the following interactions are considered to be strong interactions in Tscharntke’s food web of a Phragmites community?
Phragmites–A. geminipuncta
Phragmites–G. inclusa
T. arundinis–C. caerulus
In representing the communities in Caño Volcán, one approach used by Winemiller was to _______ the weakest trophic links.
exclude
Indirect interactions between two species require ______ species.
an intermediate
The most influential trophic relationships in a food web are known as ______ interactions.
strong
In a commensal relationship between two species, one species is ______ while there is neither harm nor benefit to the other.
benefited
In the Martinsen et al. study, the sprouts growing from trees felled by beaver have leaves that are ______ nutritious for the beetles than those growing on mature trees.
more
Which of the following trophic interactions were observed in the Phragmites community studied by Tscharntke? Arrows indicate the direction of energy flow, for example, A → B, indicates that A is eaten by B.
fly (G. inclusa) —> Blue tits
Phragmites —> moth (A. geminipuncta)
Phragmites —> fly (G. inclusa)
Stem-boring by larvae of ______ are responsible for inducing Phragmites to produce side branches.
A. geminipuncta
In the following, simplified food chain, which pairs of species have indirect interactions? Sp. A —–> Sp. B —–> Sp. C —–> Sp. D
Sp. A and Sp. C
Sp. B and Sp. D
Apparent competition is a type of ______ interaction.
indirect
Which of the following represents the indirect commensalism observed by Martinsen et al.?
Beaver — cottonwood — beetle
The purpose of the control treatment, in the experiment by Orrock et al., was to ______.
account for disturbance effects
Consistent with their hypothesis about apparent competition between mustard and bunch grass, Orrock et al. found ______ did better when ______ were excluded.
bunch grass; rodents
Predators that keep prey populations below their carrying capacity and prevent competitive exclusion by one of these species are known as ______.
keystone species
Indirect interactions between two species require ______ species.
an intermediate
In the intertidal food web of Mukkaw Bay, a ______ is considered to be the top predator.
seastar
If two species are joined through apparent competition, that means that they have a common ______.
predator
In the intertidal food web of the Gulf of California there are a total of ______ predators in the system.
11
The purpose of the experiment by Orrock et al. was to test for apparent competition between ______ and ______.
mustard; bunch grass
As a result of their experiments, Orrock et al. proposed that the rodents use ______ for protective cover, feeding on the ______.
mustard; bunch grass
A keystone species would be considered to be a type of ______.
foundation species
Paine concluded that greater numbers of predators in an intertidal community produces increased ______, leading to an increase in ______ the community.
predation pressure; diversity of
In the intertidal food web of Mukkaw Bay, the number of prey species eaten by the seastar Pisaster is ______ the number of prey species eaten by the snail Thais.
greater than
In the intertidal food web of the Gulf of California, a ______ is considered to be the top level predator.
seastar
In his first research in Mukkaw Bay on the role of predators in community diversity, Paine ______ predators for the experimental treatment in his study areas.
removed
In the months immediately following the removal of starfish, the percent of space occupied by the barnacle Balanus ______.
increased
Paine found that as the number of species in an intertidal food web increased, there was a(n) ______ in the number of predators in the community.
increase
Which three of the following factors did Lubchenco propose to be necessary in order to resolve the conflicting results of herbivore–diversity experiments?
local competitive relationships
herbivore food preference
location-based changes in competition and food preferences
Lubchenco conducted the feeding preference experiments with snails (Littorina) in a laboratory and found that perennial species of alga were eaten by the snails ______.
only when it was the only choice of food
In his first research in Mukkaw Bay on the role of predators in community diversity, the experimental sites in the experiment received ______ predators.
no
In studying the relationship between snail density and algal abundance, Lubchenco found that area’s with ______ densities of snails had low densities of the alga Enteromorpha, a ______ food.
high; favorite
Over the 2 years of Paine’s experiments in Mukkaw Bay, the diversity of the predator-free experimental plots ______ while the control plots ______.
decreased; remained constant
As in the Mukkay Bay experiment, Paine found that the removal of a sea star in the New Zealand intertidal experiment resulted in an increase in the area occupied by ______ species.
a prey
True or false: Lubchenco’s research on the relationship between herbivores and community diversity was motivated by conflicting results in previous experiments.
true
Lubchenco conducted snail removal experiments in tidal pools and found that the algae species the snails liked to eat ______ when the snails were removed.
increased in abundance
In feeding preference experiments with snails, Lubchenco found that ______ algae were generally preferred over those that are ______.
small tender; tough and perennial
After a local population explosion of seagulls, you would expect to find ______ in the abundance of the alga Enteromorpha in the tide pools.
a decrease
The seagulls would eat more crabs, and so there would be fewer crabs to eat snails. The increased number of snails would decrease the population of the algae (Enteromorpha) they like to eat.
Lubchenco studied the relationship between algal abundance and snail densities in ______.
tide pools
In the months immediately following the removal of starfish, the percent of space occupied by the barnacle Balanus ______.
increased
In Lubchenco’s study of tide pools, the snail Littorina performed a similar function to the ______ in Paine’s Mukkaw Bay experiments—controlling the populations of the dominant space competitor.
Pisaster
In both the Mukkaw Bay and New Zealand intertidal community experiments, Paine found that removal of a top predator led to ______ in the population of a space competitor.
an increase
Algal species richness was greatest at which snail density?
middle
In the tide pools in which Lubchenco removed snails, the abundance of the algae ______ increased, while the algae ______ decreased relative to the control treatment.
Enteromorpha (a favored-food choice); Chondrus
Littorina’s preference for feeding on ______ could produce the pattern of algal richness seen by Lubchenco.
the competitively dominant alga
Which one of the following would best represent food web control on the population of the snail Littorina?
snail —> crab —-> seagull
In environments where Littorina’s feeding preference is the competitively inferior alga taxa, algal richness will be lowest at which snail density?
high snail density
Lubchenco’s research ______ that of Paine, showing that a single species could control the diversity of a community.
supported
Which of the following best represents the food web of the Eel River? (Note: the arrow —-> represents as feeding relationship, e.g., A–>B is A eaten by B.)
algae –> midges –> predatory insects –> small fish –> trout
Organize the snail density conditions in order of increasing algal species richness in tide pools starting at the bottom. In other words, which snail densities produced lowest (at the bottom), middle and highest algal richness (at the top).
- middle snail density
- low snail density
- high snail density
At high densities, Littorina needed to switch to feeding on ______ in order to meet their energy needs.
less preferred alga species
The purpose of the exclosure cages in Power’s experiments was to exclude ______ from the study plots.
adults of the top predators
Experimental enclosures receiving added numbers of trout would have a(n) ______ abundance of algae as compared to enclosures with fewer trout.
decreased
In environments where Littorina’s feeding preference is the competitively inferior alga taxa, rank the density conditions in order of decreasing algal species richness with the lowest at the bottom.
- low snail density
- middle snail density
- high snail density
In Power’s study of stream communities, ______ performed a similar function as a keystone species to the snails in Lubchenco’s experiments in tide pools.
trout
In addition to feeding on invertebrates, the roach (fish) will also eat ______.
algae
Cleaner fish remove and eat ______ from other fish in coral reef communities.
parasites
Bshary observed the ______ reef patches and the presence or absence of cleaner wrasses.
number of fish species on
In Power’s experiments, she was trying to determine whether ______ and ______ were acting as keystone species.
steelhead; roach
A disease wipes out most of the trout in the Eel River. Which of the following populations would you expect to increase, at least in the short term, as a result of this?
predatory insects
roach fry
Cladophora (diatoms)
The results from Power’s study of stream communities ______ those of Paine and Lubchenco showing that a single species could control the diversity of a community.
supported
Experimental removal of cleaner wrasses from reef patches by Bshary resulted in ______ in the number of fish species on the patch.
a decrease
The activities of cleaner fish are considered to be an example of ______.
mutualism
By burying seeds of fynbos plants, ants help plants avoid losing those seeds to which of the following?
fires
rodents
True or false: Bhsary only observed naturally occurring densities of cleaner wrasses on reef patches.
false
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 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
The ability of the predaceous fire ant to act as a keystone species in arthropod communities is ______ for corn and squash farmers.
a benefit
Bshary found that reef patches with cleaner wrasses had a ______ number of fish species compared to patches where the wrasses were not present.
greater
The weaver ants have a mutualistic relationship with mealy bugs - the ants receive __________ while the mealy bugs benefit from _______________.
fluids and carbohydrates; protection from predators
Plants with large seeds produced ______ seedlings compared to plants that had small seeds that could be buried by ants.
fewer
Yang found that the weaver ants did not attack _________ of the mealy bugs.
parasites
Redford has proposed that human hunting has ______ the role of keystone species in maintaining diversity in rain forest communities.
undermined
In looking at the role of large predators, Terbough found that medium-sized mammals ______ when the predators are absent.
are more abundant
Removal of predatory fire ants from corn and squash fields would likely lead to ______ in crop damage from insect pests.
an increase
Weaver ants obtain liquids and carbohydrates from ______.
mealy bugs
Yang found that the weaver ants function as a keystone species in orange trees by feeding on ______.
larger insects
