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49 Cards in this Set
- Front
- Back
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Why is parasitism considered a +/- interaction while mutalism is a +/+? |
parasite gains benefit while host suffers
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What is symbiosis? provide examples |
-a close association between species involved in the interaction
=tapeworm =parasites =mutualism |
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what is a parasite? |
-organism that obtain nutrients from other living organisms (hosts)
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what is a host? |
organism that is infected with parasite
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It is rare for parasites to directly kill their hosts. why? |
they feed on the host and need them to survive
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how do parasites decrease the fitness of their hosts? |
take energy from host that could be used for growth and reproduction
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What are the kingdoms that include parasites? |
all 6 kingdoms
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what is hemiparasitic? provide an example |
-obtain some nutrients from a host plant
=mistletoe, can also get energy from photosynthesis |
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what is holoparasitic? provide an example |
-gain all nutrients from hosts
=broomrape, non-photosynthetic |
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Define ecto-parasite. provide examples define endo paraside provide examples |
-inhabit external surface of hosts =mosquito, deer tick, head louse, body louse -live within host =tapeworm, hookworm |
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parasites are economically important. why? |
-negative effect on humans, livestock, and crops |
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why do some parasites use multiple host species? |
-require multiple hosts to complete life cycle - 1 for maturation and 1 for sexual maturation |
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describe the life cycle of the brainworm parasite P. tenuis as an example |
1. adults in white tail deer brain to mature 2. mates produced eggs, hatch into larvae pass through bloodstream to lungs, are coughed up and swallowed 3.leave body through feces 4. larvae in feces infect snails 5. develop into infective stage in snail 6. deer eat infected snails while grading 7. infective larvae penetrate stomach of deer and reach brain via spinal cord |
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How did malaria impact the reproductive success of female western fence lizards? |
-clutch size is 20% smaller in malaria-infected female lizards than in uninfected females
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The brightness of male zebra finch beak color is dependent on the amount of carotenoid pigments obtainsed through their diet. Do females prefer the males with bright or dull beaks? |
bright |
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what did blount observe about the allocation of carotenoids to pigmentation and the immune system when parasites are present in males? |
males only allocate carotenoids to pigmentation of beaks when parasites are fewer (instead of to immune response) -carotenoids stimulate production of antibodies |
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How did carotenoids influence the immune response in blount's experiment with zebra finch brothers? |
carotenoid pigments are needed to mount immune response to pathogens and parasites.
-brother with supplemented carotenoids had higher immune response than control |
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what evidence did blount find that females prefer males with brighter red beaks? |
9/10 instances females prefered bright red brother with supplemented carotenoids
-spent more time next to bright beak males |
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how did parasite flukes influence the surfacing and jerking behavior of killifish? |
the more parasites the more surfacing and jerking -these were more heavily preyed on |
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parasites require live hosts for their survival. then why does the fluke parasite of killifish cause indirect mortality of killifish? |
the fish eating bird is the next host of its life cycle
-needs bird host to complete life cycle |
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how do the parasites cause indirect mortality of the hosts? explain using the killifish study conducted by Dr. Kevin LAfferty and Kimo Morris |
-observed that hose infected surfaced and jerked -this increased predation rate the more intense the behavior |
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why is it important for the schistosomes to produce a large number of eggs? |
-transmission adaptation
=parasite ensures transmission to new host |
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what is a vector? name examples of vectors |
vectors facilitate transmission of parasites between hosts-mosquito vector of malaria, seed eating birds transport mistletoe to new host -vectors not affected by parasite |
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why do some parasites need vectors? |
to get from host to host |
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explain host manipulation using the example of the hairworm parasite of terrestrial insects |
-must transition from terrestrial insect to water (where adults live without host to mate and produce eggs).
-cause insects to jump in water to leave after mature |
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why does the hairworm infected insects "jump into water"? |
in order to complete life cycle
-adult lives in water without host where it mates |
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what is molecular mimicry? how does it help the parasite to escape the immune response of the host? |
-parasites cover themselves with host antigens or blood
-host is not able to tell that it is foreign (schistosomes)- host immune system does not produce antibodies |
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what is an antibody? what is an antigen? |
-antibody= type of protein produced by white blood cells
antigens= proteins released by the parasite |
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what is antigenetic variation? how does it help the parasite evade the host immune system? |
change antigen at regular intervals to confuse host immune response
-host must make new antibodies for every new antigen |
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describe the adaptations of hosts against parasitic infections |
1. behavioral adaptations
2. inflammation (brings white blood cells that form antibodies 3. Gall/cyst formation 4. production of antibodies |
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what is the "red queen hypothesis" |
-host reproduce sexually to increase genetic variety creating moving target for parasite
-coevolution of parasites and hosts -evolutionary arms race |
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dr lively observed that the snails reproduce sexually when parasitic infections are high. what benefit do snails gain from sexual reproduction? |
-able to produce genetically different offspring that parasites are not well adapted to.
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what do we mean when we say "an evolutionary arms-race" is going on between parasite and host? |
-adaptations and counter adaptations by hosts and or parasites
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why do the introduced parasites cause mass mortality in their hosts? |
host does not have any evolved defenses because parasite is invasive
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how do parasites control host populations in a density-dependent manner? |
when parasites are transmitted through contact of host and are endemic
-crowding can increase parasite transmission rate |
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define mutualism provide example of mutualsim |
both organisms benefit from the relationship
-leaf cutter ants (cultivate fungi and fungi feeds ants) |
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what is symbiotic mutualism? |
two species involved are closely associated with each other
-at least 1 member is completely dependant on the other |
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explain the symbiotic mutualism between reef forming corals and zooxanthellae |
coral polyps feed on zooplankton (10% energy) remaining 90% comes from zooxanthellae through photosynthesis
=coral cannot survive without -Zoo. gain shelter and mineral nutrients |
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what is non-symbiotic mutulaism? provide an example |
two organisms involved but do not physically live together
-flowering plants and seed dispersers |
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trophic mutualism give examples |
species involved are specialized to obtain energy and nutrients
-legumes and nitrogen fixing bacteria (bacteria live in roots and plants gain usable nitrogen) -ungulates(cows) and gut bacteria to break down cellulose |
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defensive mutualism |
involves defending the partner in exchange for food or shelter
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dispersive mutualism examples |
transport of seed or pollen by other organisms
-bees and flowers (plant-pollinator interactions) |
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Ecologist, Daniel Janzen stimulated the growth of new Acacia shoots and prevented ants from colonizing them. What did he observe after 10 months? Why is this considered an example of a defense mutualism? |
-shoots without ants weighed less than 1/10 as much -fewer than 1/2 the leaves -1/3 number of swollen thorns -decreased survival and growth |
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some plant-polinator interactions are not mutualistic. provide an example of such interaction |
elbow orchids and wasps
-elbow orchid flower looks like female wasp =male tries to mate with plant that mimics morphology and pheromones, pollen sticks then struggles to mate -wasps gains no benefit, not mutualistic |
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compare plant-pollinator interactions, plant-seed disperser interactions are not highly specific why? |
succulent fruit covers seed, but have hard seed coat that survives digestion
- birds eat and distribute many types of seeds -seeds of a single plant species are eaten by many different types of birds |
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how can mutualism influence population dynamics? |
mutualism improves growth and reproduction of individuals involved in the association |
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what is the result of removal of one partner in a symbiotic mutualistic relationship? |
when one species is completely dependent on other species, removal leads to death of dependent partner |
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why is it difficult to identify the effect of non-symbiotic mutualism? |
when neither species is required for survival of the other, population dynamics are not straight forward
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explain the diffused mutualism between connifer-mycorrihize fungi -vole interactions |
1 -fungi assist plant with nutrient uptake and water from the soil 2 -plants provide fungi with carbon, which is a source of energy 3 - voles feed on fungi and disperse fungal spore so fungus can inhabit new roots |
