Chapter 16 Parasitism and Mutualism

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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
  symbiosisrelationship

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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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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
• 2nd factors
• Mortality
• Fecundity reduced

Most often host and parasite develop mutual
tolerance
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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