Chapter 54: Community Ecology II

Question 1

Community structure

Answer 1

• Defined by species diversity and trophic structure

Question 2

Trophic structure

Answer 2

• Feeding relationships among organisms in a community

Question 3

Food chain/web (def.)

Answer 3

Link trophic levels from producers to carnivores and track transfer of food energy

Question 4

Why most chains are limited to five or fewer steps?

Answer 4

• Energetic hypothesis

Question 5

Energetic hypothesis

Answer 5

• Length of food chains are limited because energy use is inefficient (about 10% of energy is transferred)

Question 6

Community structure and composition are affected by what?

Answer 6

• Species may have impact on structure

- Interactions within community (trophic interactions)

Question 7

Dominant species (por qué son dominante?)

Answer 7

• Species that are most abundant or that collectively have highest biomass
• Superior competitors(best at surviving under certain conditions)
• Most successful at avoiding predation

Question 8

Keystone species (def.)

Answer 8

• Species that exert strong control on community by altering the physical environment

Question 9

Ecosystem engineer

Answer 9

Organisms that have strong influence on community by altering the physical environment

Question 10

Genetic engineer

Answer 10

Organism that has some control over genetic selection

Question 11

Trophic cascades

Answer 11

• Indirect interactions between species

- Removing predator = more prey, less of the species upon which typical prey prey

Question 12

Biomanipulation

Answer 12

• Utilization of indirect interactions to restore ecosystems

Question 13

Disturbance

Answer 13

• Affects community structure

- Event that changes community composition by removing organisms or altering resource ability

Question 14

Disturbance regime characterization criteria?

Answer 14

• When
• How large
• How often
• How severe
• Extremely disturbed: high frequency and high intensity

Question 15

Importance of disturbance

Answer 15

• Allow species to populate again, restarts nutrient cycle I suppose?

Question 16

Intermediate disturbance hypothesis

Answer 16

• Moderate levels of disturbance can create conditions that foster greater species diversity than low or high levels of disturbance

Question 17

Ecological succession use?

Answer 17

• Bioremediation

Question 18

Ecological succession

Answer 18

• Transitions in species composition of community after a disturbance
• Disturbed area is colonized by variety of species

Question 19

Primary succession

Answer 19

• Occurs when environment in which substrate devoid of vegetation and other organisms usually lacking in soil is deposited

Question 20

Secondary succession

Answer 20

• Begins in an area in which soil remains after disturbance