CHAPTER 54 - CHAPTER 54: COMMUNITY ECOLOGY Overview: A...

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CHAPTER 54: COMMUNITY ECOLOGY Overview: A Sense of Community A biological community is an assemblage of populations of various species living close enough for potential interaction Concept 54.1: Community interactions are classified by whether they help, harm, or have no effect on the species involved Ecologists call relationships between species in a community interspecific interactions Examples are competition, predation, herbivory, and symbiosis (parasitism, mutualism, and commensalism). Interspecific interactions can affect the survival and reproduction of each species, and the effects can be summarized as positive (+), negative (–), or no effect (0) Competition Interspecific interactions can affect the survival and reproduction of each species, and the effects can be summarized as positive (+), negative (–), or no effect (0) Interspecific competition (–/– interaction) occurs when species compete for a resource in short supply Competitive Exclusion Strong competition can lead to competitive exclusion , local elimination of a competing species The competitive exclusion principle states that two species competing for the same limiting resources cannot coexist in the same place Ecological Niches The total of a species’ use of biotic and abiotic resources is called the species’ ecological niche An ecological niche can also be thought of as an organism’s ecological role Ecologically similar species can coexist in a community if there are one or more significant differences in their niches Resource partitioning is differentiation of ecological niches, enabling similar species to coexist in a community Resource partitioning among Dominican Republic lizards As a result of competition, a species’ fundamental niche (the niche potentially occupied) may differ from its realized niche (the portion of the fundamental niche the species actually occupies) Can a species’ niche be influenced by interspecific competition? Research shows that Balanus dries out higher on rocks. How would Balanus’ s realized niche compare to its fundamental niche?
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Character Displacement Character displacement is a tendency for characteristics to be more divergent in sympatric populations of two species than in allopatric populations of the same two species An example is variation in beak size between populations of two species of Galápagos finches Predation Predation (+/– interaction) refers to interaction where one species, the predator, kills and eats the other, the prey Some feeding adaptations of predators are claws, teeth, fangs, stingers, and poison Prey display various defensive adaptations Behavioral defenses include hiding, fleeing, forming herds or schools, self- defense, and alarm calls Animals also have morphological and physiological defense adaptations Cryptic coloration , or camouflage, makes prey difficult to spot Animals with effective chemical defense often exhibit bright warning
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This note was uploaded on 11/12/2009 for the course BIO 1510 taught by Professor Unknown during the Fall '07 term at Georgia Institute of Technology.

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CHAPTER 54 - CHAPTER 54: COMMUNITY ECOLOGY Overview: A...

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