Community Interactions

Concept: Interspecific Interactions


Concept: Ecological Niches and Competition


Concept: Competitive Exclusion and Niche Differentiation


Concept: Predation


Concept: Mimicry


Concept: Symbiosis


Related Topics

Community Interactions Additional Practice Problems

If cleaner fish consume both parasites and scales from larger fish, what would determine whether the interaction is best categorized as mutualism or parasitism?

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Explain how ants and acacia trees fulfill the definition of a mutualistic relationship.

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In their 2008 paper, Hanifin, Brodie, and Brodie looked at the co evolution of a newts (Taricha spp., top picture) and one of their potential predators, the common garter snake (Thamnopis sirtalis). The graph below shows the relationship between the amount of toxin in the skin of the newts and the garter snakes resistance to the toxin at a given location. The dashed line represents a reduction of 50% in the snake's health. Some locations may be considered co-evolutionary hot-spots, where reciprocal selection is strong Other locations are co-evolutionary cold spots, where the traits of one species don't match with the other and one species is "winning" the interaction. The letters on the graph represent 3 locations with snakes and newts.

a. In which of the three locations (if any) is co-evolution strong? In which locations (if any) is the snake "winning"? In which locations (if any) is the newt winning? Explain your reasoning. 

b. What might be an explanation for the dynamics occurring in population A, where the newt hasn't evolved toxicity and the snake hasn't evolved resistance. In other words, what might prevent a co-evolutionary arms race from occurring in this system?

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The effectiveness of Batesian mimicry is maintained by _____ selection.

a. directional

b. frequency-dependent

c. group

d. disruptive

e. stabilizing

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The principle of competitive exclusion states that

a. two species cannot coexist in the same habitat.

b. competition between two species always causes extinction or emigration of one species.

c. two species that have exactly the same niche cannot coexist in a community.

d. two species will stop reproducing until one species leaves the habitat.

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In some circumstances, grasses that initially lose tissues from being consumed by animals such as elk or cattle regrow more than they would have otherwise, and benefit from the moderate levels of grazing. Which of the following terms would best describe such a plant-herbivore interaction?

a. mutualism

b. commensalism

c. parasitism

d. predation

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Which of the following is an example of aposematic coloration?

a. a non-poisonous snake mimics the color of a poisonous one

b. the brightly colored patterns of monarch butterfly caterpillars

c. green color of a plant

d. a katydid whose wings look like a dead leaf

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Which of the following is an example of Batesian mimicry?

a. a butterfly that resembles a leaf

b. a nonvenomous larva of a moth that moves like a venomous snake

c. a fawn with fur coloring that camouflages it in the forest environment

d. a snapping turtle that uses its tongue to mimic a worm, thus attracting fish

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Which of the following is an example of Müllerian mimicry?

a. two species of unpalatable butterfly that have the same color pattern

b. a day-flying hawkmoth that looks like a wasp

c. a chameleon that changes its color to look like a dead leaf

d. one species of a non-venomous snake which rattles its tail to mimic a venomous rattlesnake

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Use the figure to answer the following question.

Treehoppers (a type of insect) produce honeydew, which ants use for food. Treehoppers have a major predator, the jumping spider. Researchers hypothesized that the ants would protect the treehoppers from the spiders. In an experiment, researchers followed study plots with ants removed from the system and compared them to a control plot. From the figure, what can you conclude?

a. Ants do somehow protect the treehoppers from spiders.

b. Ants eat the honeydew produced by treehoppers.

c. Ants reduce the numbers of treehoppers.

d. No specific conclusions can be drawn from this figure.

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Which of the following is an example of a commensalism?

a. fungi residing in plant roots, such as endomycorrhizae

b. bacteria fixing nitrogen on the roots of some plants

c. rancher ants that protect aphids in exchange for sugar-rich honeydew

d. cattle egrets eating insects stirred up by grazing bison

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If two species are close competitors, and one species is experimentally removed from the community, the remaining species would be expected to ________.

a. change its fundamental niche

b. decline in abundance

c. become the target of specialized parasites

d. expand its realized niche

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Two species of barnacles, Balanus and Chthamalus, can both survive on the lower rocks just above the lowtide line on the Scottish coast, but only Balanus actually does so, with Chthamalus adopting a higher zone. Which of the following best accounts for this niche separation?

a. mutualism

b. predation of Chthamalus by Balanus

c. primary succession

d. competitive exclusion

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The sum total of an organism's interaction with the biotic and abiotic resources of its environment is called its _____.

a. microclimax.

b. habitat.

c. logistic growth.

d. biotic potential.

e. ecological niche.

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