Interactions between 2 organisms where at least 1
benefits
Often occur though coevolution
ie. evolve together
In complex communities (rainforests, coral reefs)
Usually the rule, not the exception
Usually involves supply of
Usually denoted by
+ Organism benefits (positive interaction)
- Organism looses (negative interaction)
0 No interaction
COMMENSALISM
Association between 2 or more species
One species 'success' is increased
ie. one sp. benefits
The other species 'success' is not effected
ie. does not benefit or lose
i.e + 0
Epiphytes in trees
Trees provide substrate
Presence of Epiphytes has no effect
Algae of turtles shell
Turtle supplies substrate
Algae does not effect turtle
NB May not be a true interaction
Detritivory
Detritus dead, so no effect
Detritivore gains
+ 0 interaction
Mutualism
Both species benefit
i.e positive / positive interaction
+ +
Ant plants:
Myrmecodia beccarii, attached
to Melaluca growing in mangrove and coastal swamps
Tuberous main body
Size of a large double fist
Surface is tuberculous and bristly.
Sparse tufts of leaves
Surface of the tuber perforated by small access holes
Holes lead into a chambered interior.
Some galleries are smooth
Others are tunnel like with tuberculous walls.
Internal galleries develop even without ants
Ants often occupy the interiors,
Use the smooth walled cavities as brood cambers.
Positive return
Ants provide nutrients (prey and dead nest mates)
Stacked in the cavities with tuberculous walls.
Positive return
Acacia seeds, Eliasomes and Ants
Parasitism
One species benefits, one species is harmed
i.e. positive/negative relationship + -
eg ticks, tapeworms, threadworms, liverfluke, lampreys
'Good' parasites do not kill host
Parasitoids
Free living adults, parasitic larvae
Usually kill the host
eg Wasps, flies