Nature of Communities and Changes in Communities

Question 1

Groups of interacting species that occur together at the same place and time circumscribed by natural, arbitrary, or artificial boundaries

Answer 1

Communities

Question 2

Nexus of geography, resources, and phylogeny

Answer 2

Community Ecology

Question 3

Phylogenetically related group of species; a clade

Answer 3

Taxon

Question 4

Group of species that use the same resources even though they are taxonomically distant

Answer 4

Guild

Question 5

Subset of a community that includes species that function in similar ways but may or may not use similar resources

Answer 5

Functional Group

Question 6

Group of species that share a common resource and occur in the same community.

Answer 6

Local guild

Question 7

Group of phylogenetically related species in a community

Answer 7

Assemblage

Question 8

A phylogenetically bound group of species that use a similar set of resources with a community

Answer 8

Ensemble

Question 9

In Community assembly, Community membership depends on these three things:

Answer 9

1. Arriving at a site
2. Coping with the site’s physical environment
3. Interacting with the other species living there

Question 10

Similarities between community ecology and genetics

Answer 10

Both population genetics and community ecology are concerned with variation over space and time in the relative abundance and diversity of discrete biological variants (alleles for population genetics, species for community ecology)

Question 11

A representation of the trophic or energetic connections among species within a community

Answer 11

Food Web

Question 12

Groups of species that have similar ways of interacting and obtaining energy

Answer 12

Trophic Levels

Question 13

Representation of the trophic (vertical) and non-trophic (horizontal) interactions among species in a traditional food web

Answer 13

Interaction web

Question 14

Occurs when the rate of consumption at one trophic level results in a change in species abundance or composition at lower trophic levels (lower = to producer)

Answer 14

Trophic Cascade; sea otters eating urchin increases abundance of kelp (primary producer)

Question 15

Occurs when a consumer is indirectly helped by a positive interaction between its prey and another species

Answer 15

Trophic Facilitation

Question 16

Competitive interactions among multiple species in which every species has a negative effect on every other species

Answer 16

Competitive networks

Question 17

Buffer strong direct competition so that no one species dominates the interaction

Answer 17

Indirect species interactions

Question 18

Similar to competitive network but is more linear, i.e. species B dominates C, species A dominates B, therefore species A also dominates C.

Answer 18

Competitive Hierarchy

Question 19

The effect of one species on the abundance of another species

Answer 19

Interaction Strength

Question 20

Set of characteristics that shape a community

Answer 20

Community structure

Question 21

Number of species in a community

Answer 21

Species richness

Question 22

Commonness or rarity of species (relative abundances)

Answer 22

Species evenness

Question 23

Combination of species richness and evenness

Answer 23

Species diversity

Question 24

How to interpret a rank-abundance curve?

Answer 24

Plot the proportional abundance od each species in rank order
Richness - longer x-axis present
Evenness - steep curve = less even, gentle curve = more even

Question 25

Calculated by plotting species richness as a function of sampling effort

Answer 25

Species Accumulation Curve

Question 26

Why does the species accumulation curve plateu

Answer 26

The more you sample, the less new species will pop up in each sample until eventually you have already sampled everything

Question 27

Single species that defines much of the structure of a community (Dominant in terms of biomass or size)

Answer 27

Dominant/Foundation Species

Question 28

A species whose actions change the physical character of its environment

Answer 28

Ecosystem Engineers (red flag)

Question 29

Species that have large effects not because of their abundance, but because of the vital roles they play in their communities

Answer 29

Keystone Species

Question 30

Species that may have the same function in the community as other species within a larger functional group

Answer 30

Redundant species

Question 31

States that the more species are present in an ecological unit, the rate of ecosystem function also increases but up to some point; beyond this point, species do not have any more effect on ecosystem function.

Answer 31

Redundancy Hypothesis

Question 32

Directional change in the species composition of communities over time initiated by natural or anthropogenic disturbance

Answer 32

Succession

Question 33

Discrete event that damages or kills residents on a site

Answer 33

Distrubance

Question 34

Disturbance that kills all residents of all species on site

Answer 34

Catastrophic Disturbance

Question 35

Disturbance that falls short of wiping out all organisms from a site. Leaves residual organisms or biological legacies

Answer 35

Non-catastrophic disturbance

Question 36

Abiotic factor reducing growth, reproduction, or survival of individuals

Answer 36

Stress

Question 37

Disturbance is a product of?

Answer 37

Intensity, Frequency, and Extent

Question 38

Succession that occurs after the creation of a “blank slate” either through catastrophic disturbance or de novo creation of a new site

Answer 38

Primary Succession

Question 39

Succession that occurs after non-catastrophic disturbance

Answer 39

Secondary succession

Question 40

Stable end point that experiences little change until a particularly intense disturbance sends the community back to an earlier stage

Answer 40

Climax/Climax stage

Question 41

How does succession progress (Trajectory of Succession)?

Answer 41

• When the effect of a disturbance is catastrophic, a pioneer stage is formed thru the process of primary succession
• Secondary succession occurs after a disturbance alters a community greatly but does not destroy all life
• Intense disturbance at any stage can reset the community to a previous stage

Question 42

Studied Lake Michigan sand dunes - late 1800s
- Concluded that sites on the dunes were older further inland, i.e., formed a “chronosequence” from which temporal change could be inferred

Answer 42

Henry Chandler Cowles

Question 43

Radical, “superorganism” view of communities; species interact to promote a directed pattern of community development through “seral” stages, ending in a “climax” community

Answer 43

Frederick Clements

Question 44

Proposed the “individualistic view of succession” in which “every species is a law unto itself”
- Stated that communities are not a predictable and repeatable result of coordinated interactions among species

Answer 44

Henry Gleason

Question 45

Three Models of Succession

Answer 45

1. Facilitation
2. Tolerance
3. Inhibition

Question 46

Succession model where early-colonizing species modify the environment and enhance the establishment of later-arriving species; most likely in primary succession

Answer 46

Facilitation

Question 47

Succession model where early-colonizing species modify the environment but have no effect on later-arriving species

Answer 47

Tolerance

Question 48

Succession model where early-colonizing species modify the environment in ways that actively inhibit later-arriving species

Answer 48

Inhibition

Question 49

Species richness generally increases or decreases with successional age?

Answer 49

Increases

Question 50

The inability of a community that has undergone change to shift back to the original community type, even when the original conditions are restored

Answer 50

Hysteresis