Organisms and evolution - 4 Flashcards
ecological niche
multidemensional summary of tolerances and requirements of a species
fundamental niche
set of resources species is capable of using in absence of interspecific competition
realised niche
set of resources species actually uses in response to interspecific competition
what is the competitive exclusion principle?
when realised niche of two species are similar, one population starts to decline leading to local extinction
what is resource partitioning?
species with similar niches co-exist and exploit different components of the same resource
what is symbiosis?
close relationships between individual organisms of different species
what type of parasite lives on surface of host?
ectoparasite
what is an endoparasite?
parasite that lives within a host
do parasites have a broad or narrow niche?
narrow niche
what does the term degenerate mean?
lack structures and organs found in other organisms
what is a definitive host?
where parasite reaches sexual maturity
in which host does sexual reproduction occur?
definitive host
what occurs in the intermediate host?
developmental stages
what is a vector?
transfers parasite from host to host
what does sexual reproduction in parasites allow?
rapid evolution
what does the asexual phase in parasites allow?
rapid build up of parasite population for dispersal into next host
what are the 6 types of parasites?
- bacteria
- viruses
- nematodes
- platyhelminths
- arthropods
- protists
what is transmission?
spread of parasite to new host
what is the term used to describe the harm that parasite causes host species?
virulence
what are the two evolutionary stable strategies?
- low transmission, low virulence
- high transmission, high virulence
what are the two evolutionary unstable strategies?
- low transmission, high virulence
- high transmission, low virulence
what are four factors that can increase transmission rates?
- overcrowded, high density (host)
- use of vector
- waterborne dispersal stages
- exploiting natural behaviour of host
what happens when a parasite exploits the natural behaviour of host?
host behaviour is modified and becomes part of extended phenotype
what are four factors that can increase virulence?
- selection pressure increases parasite growth and reproduction in host
- suppress the host immune system
- modify size of host
- reduce host’s reproductive rate
