Chapter 54 Overview

Question 0

Biomass

Answer 0

What diverse communities typically produce more of

Question 1

Species diversity

Answer 1

Measures the number of species in a community (species richness) and their relative abundance

Question 2

Diverse communities

Answer 2

Also show less year to year variation in growth than less diverse communities and are more resistant to invasion by exotic species

Question 3

Trophic structure

Answer 3

Key factor in community dynamics

Question 4

Food chains

Answer 4

Link the tropic levels from producers to top carnivores

Question 5

Good webs

Answer 5

Formed by branching food chains and complex trophic levels interactions

Question 6

Energetic hypothesis

Answer 6

Suggests that the length of a food chain is limited by the inefficiency of energy transfer along the chain

Question 7

Dominant species

Answer 7

Most abundant species in community and possess high competitive abilities

Question 8

Ecosystem engineers

Answer 8

Influence community structure through their effects on the physical environment

Question 9

Bottom-up model

Answer 9

Proposes undirectional influence on community species from lower to higher trophic levels
Nutrients and other abiotic factors primarily determine community structure including abundance of primary producers

Question 10

Dominant species

Answer 10

Most abundant species in community and possess high competitive abilities

Question 11

Keystone species

Answer 11

Usually less abundant species that exert a disproportionate influence on community structure because of their ecological niche

Question 12

Top-down model

Answer 12

Proposes that control of each trophic level comes from the trophic level above with the result that predators control herbivores which in turn control primary producers

Question 13

Disturbance

Answer 13

Along with lack of equilibrium evidence suggests they are the norm for most communities rather than stability and equilibrium

Question 14

Intermediate disturbance hypothesis

Answer 14

Moderate levels of disturbance can foster higher species diversity than can low or high levels of disturbance

Question 15

Ecological succession

Answer 15

Sequence of community and ecosystem changes after a disturbance

Question 16

Primary succession

Answer 16

Occurs where no soil exists when succession begins

Question 17

Secondary succession

Answer 17

Begins in an area where soul remains after a disturbance

Question 18

What changes during succession?

Answer 18

Mechanisms that produce community like facilitation and inhibition

Question 19

What are the most widespread agents of disturbance?

Answer 19

Humans and their effects in communities often reduce species diversity

Question 20

Species richness

Answer 20

Generally declines along a latitudinal gradient from the tropics to the poles

Question 21

Species-area curve

Answer 21

Species richness is directly related to a community’s geographic size principle formalized in this

Question 22

On islands species richness

Answer 22

Depends on island size and distance from the mainland

Question 23

Climate

Answer 23

Influences the diversity gradient through energy and water

Question 24

Pathogens

Answer 24

Play in structuring terrestrial and marine communities its highlighted by recent work

Question 25

Zoonotic pathogens

Answer 25

Transferred from other animals to humans and cause the largest class of emerging human disease

Question 26

Community ecology

Answer 26

Provides the framework for identifying key species interactions associated with such pathogens and for helping us track and control their spread