Lecture 13: Mutualism and Commensalism

Question 1

Microbiome

Answer 1

• Bacteria, archaea, eukarya, viruses
• In the gut, on the skin

Question 2

Bright blue water means…

Answer 2

• nutrient poor environment

Question 3

Oligotrophic

Answer 3

• Deficiency of plant nutrients usually accompanied by abundance of dissolved oxygen

Question 4

Positive interactions

Answer 4

• neither species is harmed, and the benefits are greater than the costs for at least one species
• Positive interactions affect the abundances and distributions of populations as well as the structure of ecological communities

Question 5

Facilitation

Answer 5

each species interacting will have a benefit
- includes mutualism, commensalism, symbiosis

Question 6

Mutualism

Answer 6

• is ubiquitous, can be obligate or facultative and loosely structured
• mutually beneficial interaction b/w individuals of two species (+/+ relationship)

Question 7

Commensalism

Answer 7

• is ubiquitous
• individuals of one species benefit; individuals of the other species do not benefit, but are not harmed (+/0 relationship)
  ex. Trees provide homes for animals, animals don’t harm the trees

Question 8

Symbiosis

Answer 8

• two species live in close physical contact with each other
• Symbioses can include parasitism (+/-), commensalism (+/0), and mutualism (+/+)

Question 9

3 types of mutualism

Answer 9

• Trophic mutualism
• Habitat mutualism
• Obligate mutualism

Question 10

Trophic mutualism

Answer 10

• transfer of energy and nutrients between two species
  ex. Mutualistic relation b/w bees and plants

Question 11

Habitat mutualism

Answer 11

• Sharing a habitat
• ex. fish and shrimp

Question 12

Obligate mutualism

Answer 12

• the species are entirely dependent on each other
• Ants and their fungus

Question 13

The fungal garden of a leaf-cutter ant

Answer 13

• Obligate mutualism
• Ants select leaf that is less harmful to fungus
• Ants will chop leaf into tiny bits, mash it, weed out harmful things to fungus, poo on it to fertilize, create compost for fungus to have
• Fungus has hard time eating leaf without ant

Question 14

Facultative mutualism

Answer 14

• Interaction shifts from +/+ (mutualism) to +/0 (commensalism) or +/- (parasitism),
• relationship shifts if there are no predators around
• ex. if consumption of honeydew by ants reduces treehopper growth or reproduction
• ex. Aphids and Ants

Question 15

Cleaning station

Answer 15

• Fish line up and wait for turn to be cleaned by cleaner fish
• Go in and clean off parasites of fish
• If cleaner fish are not present, see drop in abundance and diversity of fish in community

Question 16

Great barrier reef

Answer 16

• Corals have specific poly p which is carnivorous, but also gains energy from algae to form skeleton
• Lots of colours – created by symbiotic algae
• The coral provides the alga with a home
• Nutrients (nitrogen and phosphorus) and access to sunlight

Question 17

Stenothermal

Answer 17

Adapted to narrow window of temperature

Question 18

eurythermal

Answer 18

We can live in broad range