4.2: Niches and Community Interactions
Article I. The Niche: What is a niche?
Section I.1 Tolerance
(a) Tolerance: the ability to survive and reproduce under a range of environmental circumstances (b) Habitat: the general place where an organism lives
Section I.2 Defining the Niche
(a) Niche: describes not only what an organisms does, but also how it interacts with biotic and abiotic factors in the environment (b) A niche is the range of physical and biological conditions in which a specie lives and way the species obtains what it needs to survive and reproduce (c) Resource: refers to any necessity of life, such as water, nutrients, light, food, or space (d) Part of an organism’s niche involves the abiotic factors it requires for survival (e) Biological aspects of an organisms niche involve the biotic factors it requires for survival (i) When and how it reproduces, the food it eats, and the way in which it obtains that food Article II. Competition: How does competition shape communities? Section II.1 The Competitive Exclusion Principle
(a) Direct competition between different species almost always produces a winner and a loser and the losing species dies out (b) The competitive exclusion principle: no two species can occupy exactly the same niche in exactly the same habitat at exactly the same time (c) If two species do, one will be better at competing for resources and eventually, the other will move out Section II.2 Dividing Resources
(a) Species usually divide instead of compete for resources
(b) By causing species to divide resources, competition helps determine the number and kinds of species in a community and the niche each species occupies Article III. Predation, Herbivory, and Keystone Species: How do predation an herbivory shape communities? Section III.1 Predator-Prey Relationships
(a) Predation: an interaction in which one animal capture and feeds on another animal (b) Predators can affect the size of prey populations in a community and...
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