2 - Host-Parasite Interactions Flashcards
(22 cards)
What is parasitism
A relationship where a parasite benefits at the expense of a host, without immediately killing it
Why is parasitism ecologically and medically important (5)
Regulates host populations
Influences species interactions
Causes diseases (e.g., malaria)
Affects agriculture and livestock
Supports immune/drug research in biotech
What is brood parasitism
One species lays eggs in another’s nest (e.g., cuckoos)
What is kleptoparasitism
Stealing food from others (e.g., gulls)
What is sexual parasitism
Males attach to females for reproduction (e.g., anglerfish)
What’s the difference between ectoparasites and endoparasites
Ectoparasites: Live externally (e.g., lice, fleas)
Endoparasites: Live internally (e.g., tapeworms, Plasmodium)
What are direct and indirect life cycles in parasites
Direct: One host (e.g., pinworms)
Indirect: Multiple hosts (e.g., Plasmodium)
Definitive Host
Parasite matures/reproduces (e.g., mosquito in malaria)
Intermediate Host
Temporary development stage (e.g., snail in schistosomiasis)
Reservoir Host
Maintains parasite without major harm (e.g., rodents in Lyme disease)
How do parasites transmit
Direct contact, vectors (e.g., mosquitoes), or environment (e.g., Ascaris in soil)
What is host manipulation
Parasites alter host behaviour to boost spread (e.g., Toxoplasma makes rodents fearless)
How do parasites evade the immune system
By changing surface proteins (e.g., Trypanosoma brucei)
What defences do hosts have (3)
Immune response (e.g., antibodies)
Behavioural isolation
Physiological responses (e.g., iguanas raising body temp)
How does parasitism affect host populations (3)
Reduces fitness and reproduction
Regulates populations (e.g., Caullerya in Daphnia)
Alters behaviour, increasing predation risk
What are community-level effects of parasites
Infected individuals are weaker competitors
Parasites shift food web dynamics and predator-prey interactions
How does understanding epidemiology help
It aids in disease control and managing outbreaks (e.g., malaria strategies)
What is the evolutionary arms race in parasitism
Hosts evolve defences while parasites evolve counter-defences (e.g., Myxoma in rabbits
What is the Red Queen Hypothesis
Continuous evolution is needed just to survive (e.g., snails vs. trematodes)
What’s the difference between specialist and generalist parasites
Specialists: Infect specific hosts (e.g., lice on primates)
Generalists: Infect multiple species (e.g., Toxoplasma gondii)
What is the cost of resistance for hosts
Energy spent on immunity reduces growth or reproduction (e.g., fewer eggs in birds)
What is the cost of virulence for parasites
Killing the host too fast reduces parasite spread (e.g., Myxoma virus evolved to intermediate virulence)
