Deck 9: From Populations to Communities

Question 1

Anthropologists have long wondered what happened to the inhabitants of Easter Island.It is clear that part of the island was arable.Which of the following likely occurred after the island was depopulated?

A) Primary succession
B) Regulation
C) Secondary succession
D) Determination

Answer 1

C

Question 2

Which of the following is an example of a trophic cascade?

A) A mountain lion preys upon deer and as a result the abundance of a grass species dramatically increases.
B) A large population of European rabbits grazes on an annual weed species and dramatically reduces their population.
C) A marine mammal feeds on baleen and significantly reduces their abundance in the Pacific Ocean.
D) A plant virus reduces the number of native plants in a community.

Answer 2

A

Question 3

Which of the following choices explains a dominance-controlled community?

A) Species are competitively equivalent. As a result, all species colonize a site and maintain their presence. Thus, species richness is high.
B) Species are not competitively equivalent. This means that some species will be able to colonize a site and maintain their presence, but some will not be able to do so.
C) Species can either be early species or later species, but ultimately regardless of which type of colonizer they are, each will be competitively equivalent.
D) Primary dominance is determined by density-dependent factors. As a result, the species richness is high.

Answer 3

B

Question 4

You have studied a population of birds over a three year period.You want to learn how this population experiences mortality at each phase of the life cycle.What analysis could you use to do this?

A) A k-value analysis
B) A meta-analysis
C) A structure analysis
D) A SNP analysis

Question 5

You have researched outbreaks of West Nile virus.You see a pattern whereby the numbers of incidences of outbreaks increases ten days after a period of precipitation in which daily temperature is below 20 degrees Celsius,soil moisture is between 50% to 65%,and relative humidity is above 60% over a continuous period of 5 days.What can you conclude from these data?

A) You can conclude that these environmental factors are why West Nile virus outbreaks increase.
B) You can conclude that these environmental factors are correlated with an increase in the number of West Nile virus outbreaks.
C) You can conclude that these environmental variables are correlated with an increase in the number of west nile virus outbreaks and prove the causal relationship.
D) You can conclude that west nile virus is not affected by abiotic variables.

Question 6

Which of the following terms is used to define a collection of subpopulations that can go extinct and appear again through recolonization?

A) N-hyper volume matrix
B) Hyper population
C) Metapopulation
D) Multi subpopulation

Question 7

You want to understand if many amphibians respond to chemical stimuli from predators in the same way.What is one approach you could take to test this without actually having to conduct experiments on hundreds of aquatic prey?

A) Do experiments with a few individuals and then extrapolate from there.
B) Conduct an experiment with aquatic prey from every genera of aquatic prey and compare responses.
C) Apply for a grant and hope you get enough money to test every species.
D) Peruse the primary literature and perform a meta-analysis.

Question 8

Which stage of community succession occurs when the most efficient competitors outcompete other species?

A) This stage is the primary stage
B) This stage is the initial stage
C) This stage is the secondary stage
D) This stage is the climax stage

Question 9

You review successional data,which show a subset of plants colonizing a gap in the following order: Common chickweed (annual)-> salvias (herbaceous perennial shrub)-> toyon (woody perennial shrub).Using these data,does it appear that plants are following a typical sequence of dominant vegetation? If so,which species might follow?

A) It does not appear that the typical sequence is being followed.
B) Yes, these data show that the typical sequence is being followed. The next species will likely be a late succession plant.
C) Yes, these data show that the typical sequence is being followed. The next species will likely be an early succession plant.
D) Yes, these data show that the typical sequence is being followed. The next species will likely be an herbaceous perennial.

Question 10

Which choice accurately defines species richness?

A) Species richness is the abundance of an organism in a community
B) Species richness is the total number of species per area
C) Species richness is the accumulation of all species through the lifetime of a patch
D) Species richness is the total number of species in a community

Question 11

Which of the following defines a trophic cascade?

A) A trophic cascade occurs when populations of predators and prey are disturbed by some abiotic event.
B) A trophic cascade occurs when a primary succession unfolds.
C) A trophic cascade is a process whereby abundances of a predator are reduced, and as a result, the prey's own resources increase in abundance.
D) A trophic cascade is a process whereby predators reduce abundances of their prey, and as a result, abundances of the prey's own resources increase.

Question 12

An island is newly formed by a volcanic eruption.You want to follow what happens with plant communities on the island.What type of succession is this?

A) The climax stage of community succession
B) Primary succession
C) Secondary succession
D) None of the above

Question 13

Food webs appear to be most controlled by what process?

A) Density-dependent selection
B) Bottom-up control
C) Top-down control
D) Metapopulations

Question 14

Which of the following is the correct sequence of dominant vegetation in a community undergoing succession?

A) Annual weed -> herbaceous perennials -> shrubs -> early successional trees -> late successional trees
B) Annual weed -> herbaceous perennials -> early successional trees -> shrubs -> late successional trees
C) Annual weed -> shrubs -> herbaceous perennials -> early successional trees -> late successional trees
D) Herbaceous perennials -> annual weed shrubs -> early successional trees -> shrubs -> late successional trees

Question 15

Who challenged the ideas of Hairston et al.and what did they contend?

A) The hypothesis by Hairston et al. was never challenged because it has been empirically demonstrated that the world is green due to top-down control.
B) Murdoch challenged the ideas of Hairston et al. and argued that the world is green because herbivores are limited by the defenses plants have evolved.
C) Pimm in 1966 argued that the world is green because herbivores are overwhelmed by their predators.
D) Hanski and Levins aregued that the world may still be green even if it is controlled from the bottom up.

Question 16

In what type of community are species approximately equivalent in their ability to invade gaps and hold those gaps against other species during their lifetime?

A) Dominance-controlled communities
B) Neutral communities
C) Density-dependent communities
D) Founder-controlled communities

Question 17

Assume a community undergoing succession approaches its climax stage.Which of the following predictions is most likely?

A) Once the community has reached its climax stage, then the number of species will increase.
B) Initially, species numbers increase as a result of colonization, but they should decrease following the climax since there will be competition.
C) Since the community has nearly reached its climax stage, then the number of species will be fixed.
D) Species numbers will have increased at the onset of succession, followed by the primary stage where they will decrease and then climax.

Question 18

According to Hairston et al.,why is the world green?

A) Hairston et al. speculated that herbivores overcome plant defenses, but ultimately plants have a faster growth rate and so dominate the world.
B) The assumption was that plants dominate the food web.
C) Hairston et al. thought that the world is green because of top-down control on herbivores.
D) The authors believed that the world is green because of bottom-up control on herbivores.

Question 19

In 1944,a researcher observes 710 ithomiine butterflies in a lek in a Central American rainforest.In 1945,1946,and 1947,the same researcher observed 722,711,744,and 702 individuals in a lek at the same location.In 2012,a different researcher revisited the same location and observed 694 ithomiine butterflies in the lek.What can you say about the stability of these ithomiine butterflies?

A) Nothing has really changed from 1944 to 2012.
B) The population has not fluctuated through time.
C) The population has experienced a steady decline.
D) None of the above.

Question 20

Approximately 20 years ago,a large fire burned through part of a national park.You are shown data that describe the species identified and enumerated over this 20 year period.These data show that some species colonized the land relatively fast.Those same species,however,are not present in the last 5 years of the data.Other species appear to maintain abundances throughout the 20 years.How would you characterize this process?

A) This is the process of primary succession
B) This is the process of community succession
C) This is because the community is a founder-controlled community
D) This is a metapopulation patch and all of the species are part of a metapopulation.

Question 21

Key factor analysis has been renamed because?

A) Killing power became a new term
B) It was not really a "factor" analysis as much as a life phase analysis
C) The concept was not all that useful to help understand populations
D) None of the above

Question 22

Which of the following describe the process of community succession?

A) Dominant species losing out to those that are better colonizers.
B) Later colonizers can often tolerate lower resource levels.
C) Good dispersers typically win in the end.
D) Later colonizers are often more efficient competitors.

Question 23

Based on what you know about complexity and stability,if a model showed species richness was very high throughout a whole community,what would you expect community stability to be like?

A) Community stability should be little to nonexistent because there would be a lot of turnover.
B) Community stability should be high, since models indicate stability increases with complexity.
C) Community stability should be low, since models indicate stability decreases with complexity.
D) Community stability would be just as unstable as the population.

Question 24

A climax community:

A) Is typically immune to disturbance.
B) Usually depletes the resources in a habitat.
C) Typically has fewer species than a community at earlier stages of succession.
D) Is often at maximum species richness.

Question 25

In founder-controlled communities:

A) Species are approximately equivalent in their ability to invade gaps.
B) Colonizing species are relatively equal as competitors.
C) One species, "founder," typically controls community outcome.
D) Gaps are resistant to colonization.

Question 26

As succession proceeds:

A) The available resources are likely declining.
B) Better competitors are beginning to dominate.
C) Environmental conditions change as species colonize.
D) Some species will not colonize until long after a disturbance.

Question 27

When the order of colonization impacts competitive outcomes:

A) It is called a priority effect.
B) Species that may otherwise be superior competitors may lose competitive outcomes.
C) It is called dominance-controlled.
D) None of these are true.

Question 28

Which of the following are examples where primary succession could occur?

A) A volcano erupted and created new bedrock
B) A tornado clears farm land
C) A glacier retreats and exposes substrate
D) Waves that sweep the shore

Question 29

Metapopulation theory:

A) Had its genesis with island biogeography
B) Refers primarily to populations within patches
C) Has lost favor among most ecologists
D) None of the above

Question 30

Which of the following might be considered primary succession:

A) Colonization of a newly formed volcanic island.
B) Regrowth after timber harvest.
C) Colonization after a severe hurricane.
D) Colonization of exposed land after glaciation retreat.

Question 31

What term describes structured analyses that use large numbers of data sets to discern consistent trends?

A) A metapopulation
B) A meta-analysis
C) A meta-index
D) A metaphore

Question 32

k-values are highest when

A) Reproduction is also high.
B) survivorship is also high.
C) morality is low.
D) mortality is high.

Question 33

When one studies metapopulations the following can occur:

A) Subpopulations can go extinct
B) Subpopulations are usually more stable than the metapopulation
C) Like islands the smallest patches are often the most frequently colonized
D) Subpopulations can be very similar in size to one another

Question 34

In highly agricultural areas,fencerows provide habitat and refugia for wildlife.You might assume:

A) Metapopulation analysis is more appropriate now than before land modification to agriculture.
B) Some species may go extinct in some fencerows but not others.
C) Smallest fencerows may see the most frequent species extinctions
D) For it to be a metapopulation organisms must be able to go from one fencerow to other fencerows.

Question 35

A high k-value would be related to density dependence if

A) It occurred when densities were low.
B) It occurred when densities were high.
C) It occurred in the larval stage.
D) It occurred in the juvenile stage.

Question 36

Species richness refers to:

A) How evenly distributed species are within a habitat.
B) How productive species are within a community.
C) The number of primary producers within a community.
D) The total number of species within a community

Question 37

After heavy rainfalls,invasive crayfish numbers in local mountain streams drop dramatically.Which statement is most accurate?

A) This proves that heavy rains wash out invasive crayfish
B) This is an observation that suggests invasive crayfish are poor swimmers
C) This suggests there is a correlation between heavy rainfall and crayfish reductions
D) None of these are accurate

Question 38

If one were to plot species numbers in a community after a disturbance over a long time period

A) Species numbers would be lowest right after a significant disturbance.
B) Species numbers would be highest midway through the time toward climax community.
C) Species numbers would decrease as better competitors colonized.
D) Species numbers would theoretically be hump shaped with time.

Question 39

All keystone species are predators.Is this accurate?

A) Yes, a keystone species by definition is a predator.
B) Yes, a keystone species cannot be found at a low trophic level.
C) No, only grazers are keystone species.
D) No, any species can theoretically be a keystone species.

Question 40

Any species that has a low abundance but exerts strong effects upon the community through multiple trophic levels would be considered which of the following?

A) An early species
B) A late species
C) A keystone species
D) A gap species

Question 41

The connection between food web complexity and stability is more complex than once thought.Currently we think that populations are actually _________ stable when the web is complex and the aggregate whole community might be _________ stable when the web is complex.

A) More, less
B) Less, more
C) More, more
D) Less, less

Question 42

Beavers build dams that create flooding that creates abundant aquatic habitat.They might be considered ______________?

A) Mesopredators
B) Megapredators
C) Keystone species
D) Top down controllers

Question 43

The ___________ of the abundances of individuals is the combination of the effects of all factors and processes that affect population density,whether density-dependent or not.

A) Regulation
B) Determination
C) Maintenance
D) Correlation

Question 44

When modeling food webs scientists take into account: the number of species they contain,the connectance of the web and _____________

A) The number of predators in the web.
B) The number of producers in the web.
C) The average interaction strength between pairs of species.
D) None of the above

Question 45

Some marine mussel communities do not change even after strong storms.They might be considered ______________?

A) Resilient
B) Resistant
C) Robust
D) Fragile

Question 46

If the numbers of a predatory Orca whale can determine the abundances of an abalone despite the fact that Orcas don't prey on abalone we would call that a/an ________

A) Indirect effect
B) Direct effect
C) Food web effect
D) Mesopredator effect

Question 47

Which of the following might be best explained by a trophic cascade?

A) Numbers of a snail eating fish go up and the numbers of snails go down.
B) Numbers of lions go down and the numbers of zebras go up.
C) Numbers of grazing catfish go down and numbers of algae go up.
D) Numbers of a stream predatory fish go up and numbers of algae go down.

Question 48

The tendency of a population to decrease in size when it is above a certain level,but to increase in size when it is below that level describes how abundance is _________________ ?

A) Determined
B) Correlated
C) Regulated
D) Maintained

Question 49

If all trophic levels are being controlled by the abundance of resources available to plants it would be called _____________.

A) Bottom up control.
B) Top down control
C) Trophic limitation
D) Producer limitation

Question 50

What do you call a series of similar communities that are in different stages of succession all in order?

A) Successional timing.
B) Sequential succession.
C) Chronosequence.
D) None of the above