Lecture 20: Mutualisms Flashcards
Mutualism
+/+
mutually beneficial interaction between individual of two species
Commensalism
+/0
interaction between individuals of two species in which one species benefits and other is not affected
Amensalism
-/0
An interaction between individuals of two species in which one species is hurt while the other is unaffected
Symbiosis
Individuals of two species live in physiological contact with other
Not all mutualisms and commensalisms are
symbiosis
Not all symbioses are
mutualistic
Obligate mutualisms
Not optional, interaction is needed for survival
Facultative mutualisms
Optional, the interaction is loose and not necessary for every individual of a species for survival
Ex. Leaf Cutter ants and Fungi Mutualistic Relationship
Ant give fungi housing and food (leaves)
Fungi turns leaves into food for the ants
Both species benefit
Ex. Acacia tree and ant mutualistic relationship
Ant gives the tree protection from herbivores
Plant houses and feed the ant
Ant are protecting trees from herbivores, trees are feeding and housing the ants
With a lower herbivore pressure, trees decrease their feeding of the ants
Interaction looks at
Costs and benefits for species A
Costs and benefits for species B
Mutualism interaction benefits and costs
Benefits > costs (for both species A and B0
Mutualism is NOT altruism. Altruism is
behavior of an individual that benefits another at its own expense
Ex. Yucca and Yucca Moths
Evidence of active punishment of cheaters
If moths lay too many eggs in the ovaries, plant has higher chance of aborting the flower
Why are mutualisms not altruistic?
Each species benefit from the interaction
If cheating occurs the interaction will often fall apart of become parasitic
Mutualisms can easily turn into
competitive or other negative interactions
Costs and benefits in a mutualism can be
context dependent
Mutualisms are generally facultative or obligate mutualisms?
Facultative mutualisms
Mutualism characteristics defined by interaction type:
- Trophic (energy/nutrients)
- Habitat (providing shelter)
- Service (pollination, dispersal, defense)
Different mutualistic relieve ____ and create _____
different stressors; resource heterogeneity
Herbivore stress
Nutrient stress
Water stress
Why is mutualism important?
- Critical to community structure (just like predator/prey or competition)
- May expand environments suitable for species (realized niche > fundamental niche)
- Mutualisms can be important to understand for conservation (persistence of a species may be completely or partially dependent on another and effect if they go extinct)
