12_Communities and food webs_BI370

Ecological Community

Groups of interacting species in the same place and time. Defined by physical boundaries or biological associations.

Species Diversity

Number and abundance of species.

Species Richness

The number of different species present

Shannon Index

-1*(sum of)pi*ln(pi)

Taxonomic Affinity

Species with the same ancestry

Guild

Species using the same resources, may be distantly related

Functional Group

Species with similar community functions (N-fixing plants)

Species Evenness

Relative abundance of species.

Ecological Redundancy

Two or more species perform the same ecological function

Foundation Species

Large impact due to size or abundance

Keystone Species

Large effect on ecosystem despite abundance/ size.

Direct Species Interactions

Predation, parasitism, amensalism, competition.

Indirect Species Interactions

One species impacts a species that impacts a third species.

Relative Interaction Intensity (RII)

(C-E)/(C+E)

Ranked Abundance Curve

Plot of relative abundance from most to least; flatter line = more even

Species Accumulation Curves

Number of species identified per sampling effort; as line flattens, most species have been identified

Community Composition

The specific species present in a community.

Genetic variation

Unique alleles and heterozygosity

Population viability

“health bar” for population

Filter of species

Set by region (pool of available species), then dispersal (local presences), then environmental conditions (dispersed), then biotic conditions (dispersed and surviving)

Trophic facilitation

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

Competitive hierarchy

Linear chain of competing species (A>B>C, A>>C)

Competitive networks

Group of species that all compete directly with each other; results in stable competition

Negative feedback loop

A increases, so B decreases, so C increases, so A decreases