Lecture 13

Question 1

Positive Interactions

Answer 1

• have influenced key events in the history of life
• Continue to shape communities and influence ecosystem functions

Question 2

Obligate

Answer 2

• It is lacking in nutrients

Question 3

Clear

Answer 3

• no photosynthetic life present

Question 4

Concept 15.1

Answer 4

• In positive interactions, neither species is harmed and the benefits are greater than the costs for at least one species

Question 5

Commensalism

Answer 5

• Millions of species form +/0 relationships with organisms that provide habitat
  Ex. Ex. birds and elephants
• Elephant isn’t being bothered or affected (0)
• The birds are feeding on things that are being kicked off by the elephants (+)

Question 6

Mutualism

Answer 6

• Mutually beneficial interaction between individuals of two species (+/+)
  Ex. bees and pollen

Question 7

The Fungal Garden of a Leaf-Cutter Ant

Answer 7

• Human farming 12,000 years ago
• Ant fungal gardening 60 million years ago
• Types of hyphae are swollen to form nutritive gongylidia that the ants feed on

Question 8

From Benefactor to Competitor

Answer 8

• Take small flower forget me not
• Live in swampy very wet areas
• Alot of water causes soil to become anoxic: bacteria eats up the oxygen
• Want water for evaporation but also want it with oxygen
• Given a shift in the environment causes a change in the temperature

Question 9

Concept 15.2

Answer 9

• Each partner in a mutualistic interaction acts in ways that serve its own ecological and evolutionary interests

Question 10

A Facultative Mutualism

Answer 10

• The interaction shifts from +/+ (mutualism) to +/0 (commensalism) or +/– (parasitism)
• relationship shifts if there are no predators around
• if consumption of honeydew by ants reduces treehopper growth or reproduction
• relationships shifts if there are no predators around

Question 11

Cheaters

Answer 11

• individuals that increase offspring production by overexploiting their mutualistic partner
  
  • Can occur is moths lay too many eggs and the larvae eat too many seeds
    
    • Yuccas can selectively abort flowers with too many eggs before the moth larvae hatch

Question 12

Concept 15.3

Answer 12

• Positive interactions affect the abundances and distributions of populations as well as the structure of ecological communities

Question 13

Corals Form Mutialisms with Symbiodimium

Answer 13

• The coral provides the alga with a home
• Nutrients (nitrogen and phosphorus) and access to sunlight

Question 14

Alga

Answer 14

• provides the coral with carbohydrates produced by photosynthesis
• And indirect assistance with deposition of their calcium carbonate skeletons