L. 27 - Trophic Ecology

Question 1

LO

Answer 1

• Review how organisms get their energy
• Describe the concept of trophic levels
• Explain how energy flows within ecosystems
• Describe food chains and food webs (“eat or be eaten”)
• Describe the various types of ecological interactions among species
• Link ecological interactions to the flow of energy through trophic levels using herbivory as an example
• Appreciate the science behind ecological knowledge and understanding

Question 2

Food chains

Answer 2

Describe energy flow between organisms amoung trophic levels
- Arrows point in direction of energy flow

Question 3

Food webs

Answer 3

More complex interactions of direction of energy flow
The number of links is often short
- Arrows point in direction of energy flow

Question 4

Trophic cascades

Answer 4

• Arrows go in direction of pressure applied, opposite to food webs

Question 5

Hypoptheses as to why Food chains are short

Answer 5

1. Energy is lost between trophic levels
   - ~90% is lost as heat between each level
2. Dynamic stability
   - longer food chains are less stable because fluctuations at low levels magnify at high levels (metronome example)

Question 6

Ecological interactions in Food webs

Answer 6

Mutualism (+/+)
Intra & Inter specific Competition (-/-)
Predation, Herbivory, Carnivory, Parasitism (+/-)
Commensalism (+/o)
Amensalism (-/o)
No interaction (o/o)

Question 7

Mutualism

Answer 7

(+/+)

Obligate Mutualism:
- Both partners can only exist together with symbiosis

Faculative Mutualism:
- Benefit from eachother, but can survice alone

Question 8

Competition

Answer 8

(-/-)

• Can have a winner, but everyone is at a loss
• Interspecific = between different species (food)
• Intraspecific = within a species (mating)

Question 9

Herbivory

Answer 9

(+/-)
- effects on populations = community level responses
- Indirect effects, presence in area has affect on another species indirectly