Chapter 54: Community Ecology

Question 1

Community

Answer 1

A group of populations of different species living close enough to interact

Question 2

Interspecific Interactions

Answer 2

A relationship between individuals of two or more species in a community

Question 3

Interspecific Competition

Answer 3

• -/- interaction

- Individuals of different species compete for a resource that limits their growth and survival

Question 4

Competitive Exclusion

Answer 4

• 2 species competing for the same limiting resources cannot coexist permanently in the same place
• Slight reproductive advantage will eventually lead to local elimination of the inferior competition

Question 5

Ecological Niche

Answer 5

Sum of a species’ use of biotic and abiotic resources in its environment

Question 6

Resource Partitioning

Answer 6

The differentiation of niches that enables similar species to coexist in a community

Question 7

Character Displacement

Answer 7

Tendency for characteristics to diverge more in sympatric than in allopatric populations of two species

Question 8

Predation

Answer 8

• +/- interaction

- One species (predator) kills and eats the other (prey)

Question 9

Aposematic Coloration

Answer 9

• Bright warning coloration
• Adaptive (predators often avoid)
• Animals with effective chemical defenses will exhibit this

Question 10

Cryptic Coloration

Answer 10

• Camouflage

- Makes prey difficult to see

Question 11

Batesian Mimicry

Answer 11

Palatable / harmless species mimics an unpalatable / harmful one

Question 12

Müllerian Mimicry

Answer 12

Two or more unpalatable species resemble each other

Question 13

Herbivory

Answer 13

• • / -

- Organism eats part of a plant / agla

Question 14

Symbiosis

Answer 14

Relationship between individuals of two or more species that live in direct and intimate contact with each other

Question 15

Parasitism

Answer 15

• +/-

- One organism (parasite) derives its nourishment from another organism (host)

Question 16

Parasite

Answer 16

• An organism that feeds on the cell contents, tissues, or body fluids of another species while in or on the host organism
• Harm but usually do not kill the host

Question 17

Host

Answer 17

• The larger participant in a symbiotic relationship

- Often provides a home and food for the smaller symbiont

Question 18

Endoparasites

Answer 18

Parasites that feed on the external surface of a host

Question 19

Mutualism

Answer 19

• Interspecific reaction that benefits both species

- +/+

Question 20

Commensalism

Answer 20

• Interaction between species that benefits one species but neither harms nor helps the other
• +/0

Question 21

Facilitation

Answer 21

• Interaction where species can have positive effects on survival / reproduction of other species
• • / +
• Not necessarily living in the direct and intimate contact of a symbiosis

Question 22

Species Diversity

Answer 22

• Variety of different kinds of organisms that make up a community
• 2 components:
  - Species richness
  - Relative abundance

Question 23

Species Richness

Answer 23

Number of different species in the community

Question 24

Relative Abundance

Answer 24

Proportion each species represents of all individuals in the community

Question 25

Shannon Diversity (H)

Answer 25

Widely used index to compare diversity based on species richness and relative abundance

Question 26

Biomass

Answer 26

Total mass of all organisms in a habitat

Question 27

Invasive Species

Answer 27

Organisms that become established outside their native range

Question 28

Trophic Structure

Answer 28

- The different feeding relationships in an ecosystem | - Determine the route of energy flow and the pattern of chemical cycling

Question 29

Food Chain

Answer 29

The pathway along which food energy is transferred from one trophic level to trophic level, beginning with producers

Question 30

Food Web

Answer 30

Food chains linked together

Question 31

Energetic Hypothesis

Answer 31

- Suggests that the length of a food chain is limited by the inefficiency of energy transfer along the chain - 10% is stored in the organic matter of each trophic level

Question 32

Dominant Species

Answer 32

Species in a community that are the most abundant or that collectively have the highest biomass

Question 33

Keystone Species

Answer 33

A species that is not necessarily abundant in a community yet exerts strong control on community structure by the nature of its ecological role or niche

Question 34

Ecosystem Engineers

Answer 34

- Foundation species | - Species that dramatically alter their environment

Question 35

Bottom-Up Model

Answer 35

- V-->H - Postulates an unidirectional influence from lower to higher trophic levels - N --> V --> H --> P

Question 36

Top-Down Model

Answer 36

- Predation mainly controls community organization | - P to H to V to N

Question 37

Biomanipulation

Answer 37

An approach that applies the top-down model of community organization to alter ecosystem characteristics

Question 38

Disturbance

Answer 38

An event (i.e. storm, human activity) that changes a community by removing organisms from it or altering resource availability

Question 39

Nonequilibrium Model

Answer 39

Describes most communities as constantly changing after a disturbance

Question 40

Intermediate Disturbance Hypothesis

Answer 40

States that moderate levels of disturbance foster greater species diversity than do high or low levels of disturbance

Question 41

Ecological Succession

Answer 41

- Transition in the species composition of a community following disturbance - Establishment of a community in an area virtually barren of life

Question 42

Primary Succession

Answer 42

Ecological succession beginning in a virtually lifeless area where soil has not yet formed

Question 43

Secondary Succession

Answer 43

Occurs when an existing community has been cleared by some disturbance that leaves the soil intact

Question 44

Evapotranspiration

Answer 44

- The evaporation of water from soil and plants | - A function of solar radiation, temperature, and water availability

Question 45

Species-Area Curve

Answer 45

All other factors being equal, the larger the geographic area of a community, the more species it has

Question 46

Pathogens

Answer 46

Disease-causing microorganisms, viruses, viroids, or prions

Question 47

Zoonotic Pathogens

Answer 47

Pathogens transferred to humans from other animals, either through direct contact with an infected animal or by means of an intermediate species

Question 48

Vector

Answer 48

- Intermediate species that spreads a zoonotic pathogen | - Often parasites