Chapter 16 Parasitism and Mutualism types, modes of transmission coevolutionary relationships population regulation

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

Parasites 2 organisms together with one deriving nourishment at the expense of the other Can result in disease

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

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

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

Beneficial relationships

Host response Behavioral changes Inflammatory Activation of the immune system Reduced host reproduction 2 nd factors Mortality Fecundity reduced

Mutual tolerance

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

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

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

Nutrient transfer- mutualism

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

Geographic range/ interdependence