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species interactions
| Question | Answer |
|---|---|
| commensalism and example | one organism benefits, the other neither benefits nor harms. ex) eyelash mites live and feed on eyelashes, humans aren't affected |
| parasite characteristics | -try to increase their fitness and move onto the next gen -cause harm but not immediate death to the host -often highly host specific (host is its habitat) -live on (ecto) or in (endo) host -use one host species per life stage of the parasite |
| where does sexual reproduction occur (which host) for parasites | the definitive host |
| effects of parasites (4) | -reduce host fitness -regulate host populations (keeping them below carrying capacity) -mediate interactions between species -affect sexual reproduction |
| bubonic plague parasites | due to fleas, killed 1/3 of Europe's population, last dip in human population |
| typhus | wiped out Napoleons campaign into Russia |
| smallpox and measles | viruses brought by Cortez to the New World |
| influenza | 1919 pandemic that killed 25-50 million people |
| ectoparasite characteristics | -specialized morphology and behavior to stay attached to the host -resources variable -broader host range (variable) |
| endoparasite characteristics | -complex life history -simple morphology (no specialized structures) -must adapt to conditions like low O2 -high resource predictability -high host specificity and highly specialized physiology |
| microparasites characteristics | -infections short -long-lasting immunity (memory cells) -multiples directly in host |
| examples of directly transmitted microparasites | smallpox, measles, COVID |
| macroparasites characteristics and examples | -<1 generation per infection -persistent infection -little immunity -few infected per host -ex) fleas, ticks, lamprey, lice |
| what is the SIR model? | susceptible (infection) to infected (recovery) to recovered and immune |
| what does the SIR model depend on | numbers of hosts in three categories, not total number of parasites |
| when does disease spread according to the SIR model? | if the number of susceptible individuals is sufficiently high and packed close together |
| consequences (disease) | -infectious diseases more likely to invade & persist in large populations -diseases w/ high transmission rate have lower threshold densities |
| what do vaccination programs aim to do? | don't need to vaccinate everybody to eradicate the disease, just enough to go below the threshold density |
| oscillatory dynamics (disease) | -infection goes to immunity or death, which lowers density of susceptibles -density of susceptibles (S) increases due to birth -when S>Nt (threshold density) there's a new epidemic -if a sick indiv. can infect <1, incidence of disease declines |
| when are diseases virulent? (4 things) | -if disease is new to host -if natural mortality of host is high -when disease is transmitted from mother to offspring -when multiple strains of the disease occur in one host. competition increases |
| life cycle of malaria | -plasmodium go through a vertebrate, sexually reproduce in mosquito (insect host half of life cycle) -goes through humans by mosquitoes making contact (vertebrate host half of life cycle) |
| facultative mutualism examples | very flexible, species can survive independently -seed dispersal -cleaner fish (pick ectoparasites off animal's bodies) -pollination |
| obligate mutualism examples | two species are dependent on each other -termites and protozoa: termites feed on wood, protozoa break down cellulose -cellular organelles (mitochondria) |
| example of defense mutualism | ants live inside thorns on trees that keeps other animals off trees |
Created by:
madalynes