Ecological Relationships Due: __________________
Species Interaction: Section 20.1 (pages 399 – 404)
KEY POINTS: Prey and predator adaptations
Identify specific interspecies competition
Compare parasitism, mutualism and commensalism
Answers Bolded!
Predation: an individual of one species (predator) eats all or some parts of another
species (prey)
How is predation a powerful force in a community? Predation influences size of
populations and effects where each species lives.
Why have predators developed adaptations over time? They must be able to
adapt to find, capture, and consume prey
What are 2 adaptations that have been selected for? Sharp teeth, speed,
camoflauge
Why would a prey also develop adaptations? Need to escape, avoid, or ward off
predators
What are 2 ways animal prey have adapted? Deceptive markings and
chemical defenses, mimcry
What are 2 ways plant prey have adapted? Physical defenses and
chemical defenses
Interspecific Competition: two or more species use the same limited resource
Cite an animal & plant example: lions and hyenas eat zebras; plants need soil
and sunlight
Competitive Exclusion: when one species is eliminated from community because of
competition for limited resource
How does competitive exclusion tie back into species occupying a specific niche?
Competition between species dictates the specific niche occupied by those species
How is the fundamental niche different than the realized niche? Fundamental niche is
the range of conditions and resources a species can tolerate and use; Realized niche
is the part of the fundamental niche that is actually used by the species
What is character displacement? Describe what has occurred on the Galapagos Islands.
Differences between species due to competition. On the Galpagos Islands, finches in
close proximity have the largest difference in beak size.
What is resource partitioning? Describe how multiple birds can live in the same tree.
Resource partitioning is when species coexist with each other to use a different part
of a limited resource. Warblers can live in the same tree because they forage in
different parts of the tree.
Symbiosis: close, long-term relationships between 2 organisms
Parasitism: relationships where one individual is harmed and the other is
benefitted
How has natural selection acted on parasites? Has led to more efficient
ways to exploit the host
Explain ectoparasites versus endoparasites (give examples of parasite and
host) ecotoparasites remain outside the host; endoparasites remain inside the host
Mutualism: relationship in which both organisms benefit
What is one of the most important mutualistic relationships? pollination
Commensalism : one organism benefits, but the other is neither helped nor
harmed
Cite an example from outside your textbook. Egret and cattle
1. In the relationship between cattle egrets and Cape buffaloes, if the egrets regularly
removed ticks from the buffaloes, would this relationship still be considered
commensal?
No, because both would now benefit
2. How does predations on plants differ from predation on animals, in terms of the
usual effect on the prey?
The adaptations are different amongst plant and animal prey because plants cannot
move away from their predators.
3. Species A and B have a very similar niche. Species A recently arrived in a
location where species B previously lived and carried a disease that killed all
members of species B. Is this situation an example of competitive exclusion?
Explain your answer.
No because they were not competing over a limited resource