Lecture 20: Mutualisms

Question 1

Mutualism

Answer 1

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mutually beneficial interaction between individual of two species

Question 2

Commensalism

Answer 2

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interaction between individuals of two species in which one species benefits and other is not affected

Question 3

Amensalism

Answer 3

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An interaction between individuals of two species in which one species is hurt while the other is unaffected

Question 4

Symbiosis

Answer 4

Individuals of two species live in physiological contact with other

Question 5

Not all mutualisms and commensalisms are

Answer 5

symbiosis

Question 6

Not all symbioses are

Answer 6

mutualistic

Question 7

Obligate mutualisms

Answer 7

Not optional, interaction is needed for survival

Question 8

Facultative mutualisms

Answer 8

Optional, the interaction is loose and not necessary for every individual of a species for survival

Question 9

Ex. Leaf Cutter ants and Fungi Mutualistic Relationship

Answer 9

Ant give fungi housing and food (leaves)
Fungi turns leaves into food for the ants

Both species benefit

Question 10

Ex. Acacia tree and ant mutualistic relationship

Answer 10

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

Question 11

Interaction looks at

Answer 11

Costs and benefits for species A
Costs and benefits for species B

Question 12

Mutualism interaction benefits and costs

Answer 12

Benefits > costs (for both species A and B0

Question 13

Mutualism is NOT altruism. Altruism is

Answer 13

behavior of an individual that benefits another at its own expense

Question 14

Ex. Yucca and Yucca Moths

Answer 14

Evidence of active punishment of cheaters
If moths lay too many eggs in the ovaries, plant has higher chance of aborting the flower

Question 15

Why are mutualisms not altruistic?

Answer 15

Each species benefit from the interaction
If cheating occurs the interaction will often fall apart of become parasitic

Question 16

Mutualisms can easily turn into

Answer 16

competitive or other negative interactions

Question 17

Costs and benefits in a mutualism can be

Answer 17

context dependent

Question 18

Mutualisms are generally facultative or obligate mutualisms?

Answer 18

Facultative mutualisms

Question 19

Mutualism characteristics defined by interaction type:

Answer 19

1. Trophic (energy/nutrients)
2. Habitat (providing shelter)
3. Service (pollination, dispersal, defense)

Question 20

Different mutualistic relieve ____ and create _____

Answer 20

different stressors; resource heterogeneity

Herbivore stress
Nutrient stress
Water stress

Question 21

Why is mutualism important?

Answer 21

• 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)