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A group of interacting species that occur together at the same place and time is known as a(n)
community.
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Despite having a relatively small biomass, populations of grizzly bears often have strong effects on their communities. The grizzly bear is therefore an example of a
keystone species.
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The lowest possible value of the Shannon index is _______. Low values indicate _______ species diversity.
0; low
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The Shannon index is determined by applying the _______ to the proportion of each species in a community, multiplying it by the proportion once again, and then summing those values.
natural logarithm
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In a food chain, secondary consumers are _______ primary producers.
two levels above
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The trophic facilitation phenomenon described by Hacker and colleagues involves direct interactions between two plant species in the form of _______, with indirect effects benefiting a _______ of one of the plants.
commensalism; herbivore
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The studies by Powers and colleagues of northern California river ecosystems showed
that the strengths of species interactions can vary depending on the environmental context.
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Suppose you wanted to determine whether you had adequately sampled the species richness of a given community. Which of the following results would most likely lead to the conclusion that more sampling was needed to assess the species richness?
A linear species accumulation curve
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What is the fundamental distinction between a competitive network and a competitive hierarchy?
In competitive hierarchies, one species dominates the interaction; in competitive networks, no single species dominates.
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In the classic trophic cascade, sea otters feed on sea urchins, which in turn feed on kelp. Via indirect effects, a reduction in kelp abundance would likely _______ the abundance of sea otters. A reduction in sea otter abundance would likely _______ the abundance of kelp.
decrease; decrease
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