Interspecific interactions- disease + parasitism

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Define parasitism
Symbiotic relationship where one organism is harmed while the other is benefited.
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What are the two types of parasites?
Ectoparasites- external (live on outside of host) e.g. ticks/fleas/mosquitoes. Endoparasites: internal e.g. Bacteria, protists, tapeworms
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Do parasites have much of an impact on an ecosystem? Evidence for this?
Yes- can have ecosystem wide implications. e.g. Mud snails (Hydrobia) predation by shorebirds=1-2% popln. Parasitism by digenean flukes kills 8-10% of snails. (Ythan esturary, Mark Huxham)
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Why do female western fence lizards in California, infected with malaria have 20% smaller clutch sizes?
Store less fat in the winter- less energy for producing eggs
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What methods could be used to help the population of the mangrove finch in the island of Isabela, Galapagos which is a critically endangered species with only 100 individuals
Setting up dispensers with cotton fumigated with insecticides- adults line nests with fibres- parasite load of Philormis downsi reduced to almost 0%. Fewer anaemic chicks+better success rate. (Knutie et al, 2014)
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What do scientists believe was the source of Phagophius groenlandicus in common seals?
Possibly increase in the range of Harp seals from the North due to a decrease in food supply- migrated further south to the north sea
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What is the issue for managers of Yellowstone national park regarding disease in the buffalo herds?
Brucellosis abartus infects hooved animals and causes spontaneous abortion. But 60% species=immune so when herds= smaller than 200- threshold is reached where there is no reservoir for disease. However- cull down to 200? Iconic species...
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How might the presence of other species other than the usual host affect a parasite?
If able to cross species-boundary- lots more potential hosts- can reproduce + spread faster. If not- harder to infect target species- e.g. bites wasted etc.
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Example of a zoonotic disease that is currently widespread in mainland Europe but not in the UK?
Rabies- caused by Lyssavirus can infect a wide range of mammals including humans- strange+ aggressive behaviour but you think you are okay
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What is the main vector for rabies? Outline the worst + best strategy to control this.
Foxes. Culling = not effective- foxes are opportunistic + dissipate widely. Oral vaccination in food way work- but need to vaccinate 50% foxes- difficult undertaking.
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How were experiments carried out to see if myxomatosis is still affecting rabbit populations?
Flea vectors were reduced with insecticides- 3 fold increase in rabbit populations- disease must still be suppressing populations.
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Why were experiments carried out to see if rabbit populations are still affected by myxomatosis?
Some evidence for co-evolution of rabbit + virus? Rabbit= more resistant. Virus= less pathogenic- not useful if host dies- need to keep finding new hosts.
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Why might patterns of increased disease emergence have potential implications for human health + well-being?
Climate change- changing species/vector ranges= change in range of diseases/viruses- e.g. malaria? If parasite= zoonotic- could cross species boundaries = affect humans e.g. swine flu, TB, HIV, ebola, CJD etc.
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Card 2

Front

What are the two types of parasites?

Back

Ectoparasites- external (live on outside of host) e.g. ticks/fleas/mosquitoes. Endoparasites: internal e.g. Bacteria, protists, tapeworms

Card 3

Front

Do parasites have much of an impact on an ecosystem? Evidence for this?

Back

Preview of the front of card 3

Card 4

Front

Why do female western fence lizards in California, infected with malaria have 20% smaller clutch sizes?

Back

Preview of the front of card 4

Card 5

Front

What methods could be used to help the population of the mangrove finch in the island of Isabela, Galapagos which is a critically endangered species with only 100 individuals

Back

Preview of the front of card 5
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