CHAPTER 5 notes - Competition occurs with limited resources...

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CHAPTER 5 Competition occurs with limited resources o Competition= relationship where multiple organisms seek the same limited resources they need to survive Generally subtle, not outright fighting Food, water, space, shelter, mates, sunlight, etc o Intraspecific competition= between members of the same species o Interspecific competition= between members of 2 or more species o Effective competitors can completely exclude other species EX: Zebra mussels displace native mussels But some species can coexist by using different resources Resource partitioning o In competitive relationships, each participant has a negative effect on the other participant o To reduce competition, species can use a resource in slightly different ways o Resource partitioning= when species divide shared resources by specializing in different ways EX: one species is active at night, another in the daytime; one species eats small seeds, another eats large seeds Predation o Exploitive interactions= a type of interaction where one species benefits while another is harmed Predation, parasitism, herbivory o Predation= process by which individuals of one species (predators) capture, kill, and consume individuals of another species (prey) Structures food webs Influences community composition by determining numbers of predators and prey Example of predation: zebra mussels o Zebra mussels prey on zooplankton Zooplankton decrease in lakes with zebra mussels o Zebra mussels prey on phytoplankton Compete with zooplankton o Zebra mussels are becoming prey for some North American predators Ducks, fish, muskrats, crayfish Predation can drive population dynamics
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o Increased prey populations increase predators Predators survive and reproduce o Increased predator populations decrease prey o Decreased prey populations cause starvation of predators o Decreased predator populations increase prey populations Population has evolutionary ramifications o Natural selection leads to evolution of adaptations that make predators better hunters o Individuals who are better at catching prey… Live longer, healthier lives Take better care of offspring o Since prey are at risk of immediate death… They develop elaborate defenses against being eaten Parasites exploit living hosts o Parasitism= a relationship in which one organism (parasite) depends on another (host) for nourishment or other benefit, while simultaneously harming the host Usually does not immediately kill the host o Some species are free living, and infrequently contact their hosts Cuckoos and cowbirds lay eggs in other birds’ nests o Many species live within the host Disease, tapeworms o Other species live on the exterior of their hosts Sea lamprey Coevolution o Coevolution= evolution of hosts and parasites in response to each other They become locked in a dual of escalating adaptations Has been called and “evolutionary arms race”
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This note was uploaded on 03/28/2011 for the course ISB 202 taught by Professor Johnson during the Spring '08 term at Michigan State University.

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CHAPTER 5 notes - Competition occurs with limited resources...

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