Exam 18: Community Structure　

A researcher removed predatory starfish from sections of intertidal rock and found that the number of prey species decreased by 50 percent relative to control plots within a short time. This indicates that

The plot shows that most species in this community are

What is the suggested mechanism by which the presence of insecticide influences phytoplankton abundance?

Carbon dioxide with radioactive carbon was bubbled into an illuminated aquarium containing unfiltered pond water. In what order will radioactivity appear in various organisms in the aquarium?

What most accurately describes a trophic cascade?

Using the figure that follows, compare species richness and evenness.

What would be the most likely species richness-productivity relationship for a community in which the species were not resource limited?

How would adding resources such as fertilizer to an area affect the species in a community?

Consider invertebrates such as starfish and mussels on a rocky intertidal habitat where tidal cycles cause the animals to move between exposure and submersion. Are these changing conditions considered a disturbance?

What species richness-productivity relationship has the Park Grass Experiment in England demonstrated over the past 150 years?

Which statement best reflects the relationship between a disturbance and an alternative stable state?

What, in addition to tolerance to soil characteristics, might account for the distribution of plant species over different soil types?

You are sampling a stream with a net, collecting 100 macroinvertebrates. Your collection is as follows (assume the different macroinvertebrate types noted are all the same species (e.g., 17 mayflies are all of the same species): 5 caddisflies, 17 mayflies, 48 stoneflies, 6 dragonflies, 10 damselflies, 4 alderflies, 2 dobsonflies, 2 midges, 3 crayfish, 1 aquatic sowbug, 1 water penny, 1 cranefly If you were to take this data and construct a rank abundance curve, what would it look like?

What community measure does Shannon's index quantify?

Explain what the intermediate disturbance hypothesis predicts for the comparison of species richness in forests where fires have been suppressed versus those with unsuppressed natural fire.

The presence of fish has a positive effect on shoreline flowering plants. Which lines in the diagram reflect a negative direct effect?

The dams that have been built on many rivers stabilize river flow by increasing flows below the dam during droughts and decreasing the amount of flooding during periods of high rainfall. Explain how these stabilized flows can be considered as a disturbance.

Explain the relationships that appear to reduce tadpole abundance when insecticide is present, even though insecticide does not directly affect tadpoles.

Why are keystone species important in food webs?

Which response variable (on the y axis) did NOT increase with plant species richness?