Niche, Transmission and Virulence Flashcards
what is the definition of an ecological niche
a multidimensional summary of the tolerances and requirements of a species
what is the difference between the fundamental niche and the realised niche of a species
the fundamental is a set of resources a species is capable of using in the absence of interspecific competition, the realised is the resources they actually use in the presence of interspecific competition
what is resource partitioning
when two species live together but have sufficiently different realised niches so can co-exist
how does natural selection favour resource partitioning
works on competing organisms with high selection pressures and favours specialization
give an example of resource partitioning
lice on humans, beak sizes of waders
define a parasite
a symbiont that gains benefit in terms of nutrients at the expense of its host
who’s reproductive potential is greater, the parasite or their host
the parasite
what are the two types of parasites
ectoparasites and endoparasites
what is an ectoparasite?
a parasite that lives on the surface of its host
give an example of an endoparasite
tapeworm, plasmodium
do parasites tend to have a wide or narrow niche
narrow niche
describe the coevolution of parasites and their hosts and how this has affected their niche
parasites evolve in response to hosts evolution, meaning parasites will have a narrow niche and be host specific
what is a degenerate parasite
a parasite who lacks structures / organs found in other organisms
why do some parasites become degenerate
evolution favours loss of non useful structures, it is a waste of resources
what happens when a parasite is on/in its definitive host
reaches sexual maturity
what is the name of the host that contains the parasite for its developmental stages and asexual reproduction
intermediate host
describe a vector
a organism who plays an active part in the transmission of a parasite, may also be a host
what is transmission
how easily the parasite is spread
why are all viruses not just extremely virulent
because it would incapacitate the host and so it would be unable to be transmitted and so the end of its life cycle
why do some parasites have asexual and sexual stages
because asexual stages allow the rapid buildup of parasites and sexual stages allow variation required for their evolution
state the three factors that increase transmission rates
high population density, use of vectors, water borne dispersal stages
how does high population density allow an increase in transmission rates
if overcrowded more direct contact between people and also more chance of water droplets being spread more easily
what are the three ways that a parasite can increase its virulence
suppressing the hosts immune system, reducing the hosts reproductive rate and modifying the size of the host
how can modifying the size of the host affect virulence
prevent growth - all energy is diverted to parasite , promote growth - support more asexual reproduction
