Niche, Transmission and Virulence

Question 1

what is the definition of an ecological niche

Answer 1

a multidimensional summary of the tolerances and requirements of a species

Question 2

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

Answer 2

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

Question 3

what is resource partitioning

Answer 3

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

Question 4

how does natural selection favour resource partitioning

Answer 4

works on competing organisms with high selection pressures and favours specialization

Question 5

give an example of resource partitioning

Answer 5

lice on humans, beak sizes of waders

Question 6

define a parasite

Answer 6

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

Question 7

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

Answer 7

the parasite

Question 8

what are the two types of parasites

Answer 8

ectoparasites and endoparasites

Question 9

what is an ectoparasite?

Answer 9

a parasite that lives on the surface of its host

Question 10

give an example of an endoparasite

Answer 10

tapeworm, plasmodium

Question 11

do parasites tend to have a wide or narrow niche

Answer 11

narrow niche

Question 12

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

Answer 12

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

Question 13

what is a degenerate parasite

Answer 13

a parasite who lacks structures / organs found in other organisms

Question 14

why do some parasites become degenerate

Answer 14

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

Question 15

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

Answer 15

reaches sexual maturity

Question 16

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

Answer 16

intermediate host

Question 17

describe a vector

Answer 17

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

Question 18

what is transmission

Answer 18

how easily the parasite is spread

Question 19

why are all viruses not just extremely virulent

Answer 19

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

Question 20

why do some parasites have asexual and sexual stages

Answer 20

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

Question 21

state the three factors that increase transmission rates

Answer 21

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

Question 22

how does high population density allow an increase in transmission rates

Answer 22

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

Question 23

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

Answer 23

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

Question 24

how can modifying the size of the host affect virulence

Answer 24

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

Question 25

are parasites evenly distributed throughout the population

Answer 25

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

Question 26

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

Answer 26

sex, age, genotype, behaviour

Question 27

what is the extended phenotype of a parasite

Answer 27

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

Question 28

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

Answer 28

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

Question 29

what is competitive exclusion

Answer 29

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

Question 30

give an example of competitive exclusion

Answer 30

red squirrels in the UK by grey squirrels