Symbiosis are the intimate relationships that exist between species.
-
Upload
lewis-glass -
Category
Documents
-
view
34 -
download
2
description
Transcript of Symbiosis are the intimate relationships that exist between species.
Symbiosis are the intimate relationships that exist between species.
Symbiotic Relationships
Parasitism
Commensalism
Mutualism
Symbiotic relationships give at least one of theparticipants a nutritional or survival advantage.
Parasitism
An interaction between two organisms where onespecies benefits (parasite) and the other species (host)is ‘harmed’ in some way.
ParasitesObligate
Parasites dependant on
the host for survival
(viruses)
Facultative
Parasites that do not
need a host to survive.
They can live with or
without them.
Outside or Inside ?
Ectoparasites
Live on surface of the host
Ticks
Fleas
leeches
Endoparasites
Live within their host
Tapeworm
Malaria (plasmodium)
Sleeping sickness
(trypanosome)
Parasite and Host relationship
Balance between receiving nutrients and damage done.
Most parasites do not kill their host.Host could have some means of defence.Death of the host means loss for parasite.Relationship usually stable between them.
Transmission of parasite to new hostDirect Contact
Parasite moves between hosts e.g rhinovirus, influenza, head lice.
Secondary host species or vectorsOrganisms that transmit parasites e.g. fleas and ticks. The infectious stage develops inside them and is passed on e.g. toxoplasmosis, malaria
Resistant stagesOffspring released by parasite are in dormant or resistant form. When consumed by a host they become active e.g. liver fluke (snail and sheep)
Host – parasite specificityParasites have often developed with hostParasites have often shared an evolutionary path.As hosts defence system affects parasites the
most well adapted survive.
Defence against parasitesAnimalsLymphocytes – antibodiesMacrophagesPreening/groomingMigration
PlantsChemicals Localised death of cells to isolateGalls
Plant parasites
Viruses
tobacco mosaic virus
potato leaf roll virusBacteria
fireblight in apples and pearsFungi
wheat rust
grey mould
Koch’s postulate for diseasesPathogen should be present in all diseased
organisms but not healthy onesPathogen should be able to be isolated and grown
in pure cultureA healthy animal inoculated with the pure culture
should get the same disease as original animalsThe pathogen should be able to be isolated from
the newly diseased organisms
Commensalism
An interaction between two organisms whereone species (commensal) benefits and the otherspecies (host) is unaffected.
CommensalismAre there really any pure commensal relationships?
MutualismAn interaction betweentwo organisms whereboth species benefitfrom the relationship.
MutualismOrganisms involved in mutualistic relationships often benefit from increased levels of metabolites, protection, removal of parasitic organisms.
Organisms also show complementary structures or behaviours.
MutualismLichens - fungi and algae
Sea anemone and hermit crab
MutualismPlants often have symbiosis with fungi
especially in root systems.
Ectomycorrhizae – fungus on outside of cells
forming covering sheath of mycelium.
Endomycorrhizae – fungus found inside cortex
cells.