lec 15- parasites, pathogens, and disease Flashcards
what is parasitism?
when an organism uses another as a resource while it is still alive, benefiting from it while the organism host undergoes harm
what is a host for a parasite?
it is a source of food and a habitat for parasites, have ecological immunity and resistance
what type of evolution do parasites and hosts undergo?
co-evolution
what is a definitive host?
a host where parasite reaches sexual maturity
what is an intermediate host?
a host where parasite may grow, develop, or reproduce asexually
what are the types of parasites?
microparasites and macroparasites
what are the characteristics of microparasites?
-reproduce in host
-found within cells, blood, or gut of host
-short generation time, many individuals
-usually need high host densities to persist
what are the characteristics of macroparasites?
-found in cavities, between cells, on surface of body
-may use more than one host (complex life cycles because multiple hosts)
-longer generation time
-chronic re-infection possible
what are the two subcategories of macroparasites?
inside- endoparasites
outside- ectoparasites
what is vertical parasitic transmission?
infection from parents to offspring (e.g. herpes, rubella etc.)
what is horizontal parasitic transmission and the two types?
-all other methods of transmission
direct: host to host
indirect: usually third party involved (vector)
intense selection for successful transmission
how does direct host to host transmission move?
-through air
-through soil or vegetation
-contact (rabies, STDs, fleas)
mostly microparasites (internal)
what is the vector in indirect host to host transmission?
the organism that carries the parasite to the host (e.g. Tseste fly gives Trypanosome which causes sickness, Anopheles mosquito gives Plasmodium which causes malaria)
what is the SIR model used for?
to understand the ecology of disease
what are the three ways parasites can affect hosts?
individual: reproduction, mortality (directly via predators)
population: causes mass mortality, depression growth rates, can drive population cycles
communities: influences competition between hosts
(e.g. of parasite for all three is lyme disease)
how does the parasite blowfly affect the blue tit?
blowfly (parasite) lowers blue tit children health and makes it easier for them to die, requires parent to feed them more
what is the adaptations the red grouse has to limit vulnerability to parasites?
females stop producing feces when incubating, not letting fecal nematodes from coming
can parasites increase predation done on host?
yes, they have a scent which gives off their location
can parasites cause competition between species?
yes
does biodiversity control infection and parasite numbers?
yes
what does the western fence lizard have in its blood that kills the parasitic spirocheate?
a special type of protein
