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Chapter 16 Parasitism and Mutualism types, modes of transmission coevolutionary relationships population regulation
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Coevolution and symbiosis Evolution in response to interaction w/ another species Prey defenses response to hunting efficiency Closer between parasites and their hosts during symbiosis=relationship
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Parasites 2 organisms together with one deriving nourishment at the expense of the other Can result in disease
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Microparasites Viruses, Bacteria, and Protozoa Small in size Short generation time Multiply rapidly in the host Produce immunity Spread by direct transmission Assoc. w/ dense population of host Worms, lice, ticks, fleas, rusts, fungi
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Macroparasites Worms, lice, ticks, fleas, rusts, fungi Longer generation time Rarely multiply directly on host Persist w/ continual reinfection Spread by both direct and indirect transmission
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Challenges to the relationship Parasite and host Specialty sites on the host Gaining entrance and escape from the host Transmission between hosts by other organisms- vectors Or intermediate hosts- often feeding related Definitive host – intermediate - definitive
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Beneficial relationships
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Host response Behavioral changes Inflammatory Activation of the immune system Reduced host reproduction 2 nd factors Mortality Fecundity reduced
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Mutual tolerance
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Regulation of host populations After the initial introduction Mortality can spread to eventual extinction or Mutualism can develop after immune response Dependent on reciprocal relationship
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Terms to consider Obligatory – necessary to every exchange or life stage or means of surviving Facultative – can be switched to alternative route or means given an advantage Facilitative, increasing the fitness
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Symbiotic mutualisms Involved in uptake of nutrients in both animals and plants Chambers in ruminants stomach Bacteria and protozoa/ fermentation Nitrogen fixing bacteria In plant root nodules Fungi for mycorrhizal associations In plant roots
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Nutrient transfer- mutualism
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Range of mutualistic relationships Not all mutualistic are symbiotic Pollination of flowering plants Structures designed to avoid waste of pollen Optimizes or imparts a benefit Seed dispersal Place seeds inside a delicious or attractive fruiting body Survive the ride and still leave a deposit
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Geographic range/ interdependence
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