ENVS 200 Final Exam Questions With All
Correct & Verified Answers
metapopulation Correct answer-a population consisting of a collection of subpopulations, each
one of which has a realistic chance both of going extinct and of appearing again through
recolonization.
habitat patches Correct answer-Areas of suitable habitat for a species that are separated by areas
of unsuitable habitat.
disturbance Correct answer-Event that opens up a Gap
Gap Correct answer-patches within which many species suffer local extinction simultaneously. (In
forests, high winds, elephants, or simply the death of a tree through old age)
founder-controlled communities Correct answer-community where species are approximately
equivalent in their ability to invade gaps and can hold the gaps against all comers during their
lifetime. On each occasion that a population goes locally extinct a gap is opened up for invasion.
Priority Effect Correct answer-effect between competing species in which the species that arrives
first at a site is able to hold it against competing invades, whatever the outcome would be if they
competed as simultaneously arriving equals.
dominance-controlled communities Correct answer-communities where some species are
competitively superior to others and an initial colonizer of a patch cannot necessarily maintain its
presence there.
community successions Correct answer-disturbances that open up gaps lead to reasonable
predictable sequences of species, because different species have different strategies for exploiting
resources - early species are good colonizers and fast growers, whereas later species can tolerate
lower resource levels and grow to maturity in the presence of early species, eventually out-
competing them.
climax stage Correct answer-community reaches a point when the most efficient competitors oust
there neighbors. In this sequence, if it runs its full course, then number of species first increases
(because of colonization) then decreases (because of competition).
primary succession Correct answer-sequence of species, where an opened-up gaps has not
previously been influenced by a community
secondary succession Correct answer-subsequent sequence of species where the species of an
area has been partially or completely removed but seeds and spores remain.
Chronosequence Correct answer-a sequence of communities that exist over time at a given
location (as a glacier retreats, the first stage of the succession may be observed just beyond its tip,
with later stages strung out further down the glacial valley, this series of communities currently in
existence can be used to infer what the succession must have been.
food web Correct answer-complex web of interactions between an organism, and other predators,
parasites, food sources, and competitors within its community.
, Tropic level Correct answer-each of several hierarchical levels in an ecosystem, comprising
organisms that share the same function in the food chain and the same nutritional relationship to
the primary sources of energy.
direct effects Correct answer-the direct impact of one individual on another when not mediated or
transmitted through a third individual (cheetah captures a gazelle or a bee pollinate a flower, then
you have observed a direct effect in action). Separated into categories such as predation,
competition, mutualism, etc.
indirect effects Correct answer-the impact of one organism or species on another that is mediated
or transmitted by a third. In other words, A (donor) has an effect on B (transmitter), which then
affects C (recipient).
super predator Correct answer-a predator at the top of a food chain, with no natural predators.
trophic cascade Correct answer-occurs when a predator reduces the abundance of its prey, and
this cascades down to the tropic level below, such as that prey's own resources increase in
abundance.
top-down control Correct answer-when a consumer limits a prey population. Typically the
predators controlling the abundance of the herbivores, so called top-down control.
bottom-up control Correct answer-The abundance of predator populations at higher trophic levels
is regulated by the abundance of prey populations at lower trophic levels
meta-analysis Correct answer-structured analyses of large numbers of of data sets with a view to
discerning consistent trends
Why is the world green? Correct answer-the world is green because top-down control
predominates: green plant biomass accumulates because predators keep herbivores in check.
typical sequence of dominant vegetation Correct answer-annual weeds > herbaceous perrenials >
shrubs > early successional trees > late successional trees
species richness Correct answer-the number of different species in a community
diversity indices Correct answer-measures that combine both species richness and the evenness or
equitability of the distribution of individuals among these species
purpose of diversity indicies Correct answer-a community of 10 species with equal numbers in
each seems more diverse than another with 10 species in which 91% of the individuals belong to the
most common species and just 1% to the other nine, although species diversity would deem both
equally diverse.
Evenness Correct answer-relative abundance of each species
niche breadth Correct answer-The portion of resources that a species uses (n) out of the resources
available to the community (R). The variation among individuals in a population in their resource use.
Correct & Verified Answers
metapopulation Correct answer-a population consisting of a collection of subpopulations, each
one of which has a realistic chance both of going extinct and of appearing again through
recolonization.
habitat patches Correct answer-Areas of suitable habitat for a species that are separated by areas
of unsuitable habitat.
disturbance Correct answer-Event that opens up a Gap
Gap Correct answer-patches within which many species suffer local extinction simultaneously. (In
forests, high winds, elephants, or simply the death of a tree through old age)
founder-controlled communities Correct answer-community where species are approximately
equivalent in their ability to invade gaps and can hold the gaps against all comers during their
lifetime. On each occasion that a population goes locally extinct a gap is opened up for invasion.
Priority Effect Correct answer-effect between competing species in which the species that arrives
first at a site is able to hold it against competing invades, whatever the outcome would be if they
competed as simultaneously arriving equals.
dominance-controlled communities Correct answer-communities where some species are
competitively superior to others and an initial colonizer of a patch cannot necessarily maintain its
presence there.
community successions Correct answer-disturbances that open up gaps lead to reasonable
predictable sequences of species, because different species have different strategies for exploiting
resources - early species are good colonizers and fast growers, whereas later species can tolerate
lower resource levels and grow to maturity in the presence of early species, eventually out-
competing them.
climax stage Correct answer-community reaches a point when the most efficient competitors oust
there neighbors. In this sequence, if it runs its full course, then number of species first increases
(because of colonization) then decreases (because of competition).
primary succession Correct answer-sequence of species, where an opened-up gaps has not
previously been influenced by a community
secondary succession Correct answer-subsequent sequence of species where the species of an
area has been partially or completely removed but seeds and spores remain.
Chronosequence Correct answer-a sequence of communities that exist over time at a given
location (as a glacier retreats, the first stage of the succession may be observed just beyond its tip,
with later stages strung out further down the glacial valley, this series of communities currently in
existence can be used to infer what the succession must have been.
food web Correct answer-complex web of interactions between an organism, and other predators,
parasites, food sources, and competitors within its community.
, Tropic level Correct answer-each of several hierarchical levels in an ecosystem, comprising
organisms that share the same function in the food chain and the same nutritional relationship to
the primary sources of energy.
direct effects Correct answer-the direct impact of one individual on another when not mediated or
transmitted through a third individual (cheetah captures a gazelle or a bee pollinate a flower, then
you have observed a direct effect in action). Separated into categories such as predation,
competition, mutualism, etc.
indirect effects Correct answer-the impact of one organism or species on another that is mediated
or transmitted by a third. In other words, A (donor) has an effect on B (transmitter), which then
affects C (recipient).
super predator Correct answer-a predator at the top of a food chain, with no natural predators.
trophic cascade Correct answer-occurs when a predator reduces the abundance of its prey, and
this cascades down to the tropic level below, such as that prey's own resources increase in
abundance.
top-down control Correct answer-when a consumer limits a prey population. Typically the
predators controlling the abundance of the herbivores, so called top-down control.
bottom-up control Correct answer-The abundance of predator populations at higher trophic levels
is regulated by the abundance of prey populations at lower trophic levels
meta-analysis Correct answer-structured analyses of large numbers of of data sets with a view to
discerning consistent trends
Why is the world green? Correct answer-the world is green because top-down control
predominates: green plant biomass accumulates because predators keep herbivores in check.
typical sequence of dominant vegetation Correct answer-annual weeds > herbaceous perrenials >
shrubs > early successional trees > late successional trees
species richness Correct answer-the number of different species in a community
diversity indices Correct answer-measures that combine both species richness and the evenness or
equitability of the distribution of individuals among these species
purpose of diversity indicies Correct answer-a community of 10 species with equal numbers in
each seems more diverse than another with 10 species in which 91% of the individuals belong to the
most common species and just 1% to the other nine, although species diversity would deem both
equally diverse.
Evenness Correct answer-relative abundance of each species
niche breadth Correct answer-The portion of resources that a species uses (n) out of the resources
available to the community (R). The variation among individuals in a population in their resource use.
