Niche, Transmission and Virulence Flashcards Preview

Biology > Niche, Transmission and Virulence > Flashcards

Flashcards in Niche, Transmission and Virulence Deck (30)
Loading flashcards...
1
Q

what is the definition of an ecological niche

A

a multidimensional summary of the tolerances and requirements of a species

2
Q

what is the difference between the fundamental niche and the realised niche of a species

A

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

3
Q

what is resource partitioning

A

when two species live together but have sufficiently different realised niches so can co-exist

4
Q

how does natural selection favour resource partitioning

A

works on competing organisms with high selection pressures and favours specialization

5
Q

give an example of resource partitioning

A

lice on humans, beak sizes of waders

6
Q

define a parasite

A

a symbiont that gains benefit in terms of nutrients at the expense of its host

7
Q

who’s reproductive potential is greater, the parasite or their host

A

the parasite

8
Q

what are the two types of parasites

A

ectoparasites and endoparasites

9
Q

what is an ectoparasite?

A

a parasite that lives on the surface of its host

10
Q

give an example of an endoparasite

A

tapeworm, plasmodium

11
Q

do parasites tend to have a wide or narrow niche

A

narrow niche

12
Q

describe the coevolution of parasites and their hosts and how this has affected their niche

A

parasites evolve in response to hosts evolution, meaning parasites will have a narrow niche and be host specific

13
Q

what is a degenerate parasite

A

a parasite who lacks structures / organs found in other organisms

14
Q

why do some parasites become degenerate

A

evolution favours loss of non useful structures, it is a waste of resources

15
Q

what happens when a parasite is on/in its definitive host

A

reaches sexual maturity

16
Q

what is the name of the host that contains the parasite for its developmental stages and asexual reproduction

A

intermediate host

17
Q

describe a vector

A

a organism who plays an active part in the transmission of a parasite, may also be a host

18
Q

what is transmission

A

how easily the parasite is spread

19
Q

why are all viruses not just extremely virulent

A

because it would incapacitate the host and so it would be unable to be transmitted and so the end of its life cycle

20
Q

why do some parasites have asexual and sexual stages

A

because asexual stages allow the rapid buildup of parasites and sexual stages allow variation required for their evolution

21
Q

state the three factors that increase transmission rates

A

high population density, use of vectors, water borne dispersal stages

22
Q

how does high population density allow an increase in transmission rates

A

if overcrowded more direct contact between people and also more chance of water droplets being spread more easily

23
Q

what are the three ways that a parasite can increase its virulence

A

suppressing the hosts immune system, reducing the hosts reproductive rate and modifying the size of the host

24
Q

how can modifying the size of the host affect virulence

A

prevent growth - all energy is diverted to parasite , promote growth - support more asexual reproduction

25
Q

are parasites evenly distributed throughout the population

A

no, a small number of people have a high parasitic burden

26
Q

what factors could affect whether a person has a high parasitic burden

A

sex, age, genotype, behaviour

27
Q

what is the extended phenotype of a parasite

A

when a parasite exploits the natural behaviour of its host to maximise transmission

28
Q

what are the five categories of ways a host behaviour can be modified

A

foraging, movement, sexual behaviour, habitat choice and anti predator behaviour

29
Q

what is competitive exclusion

A

when two species have very similar realised niches and one is outcompeted to local extinction

30
Q

give an example of competitive exclusion

A

red squirrels in the UK by grey squirrels