Community Structure and Interactions

Community structure

Description of a community, it's location, membership, and other relevant characteristics

The set of characteristics that shape communities, is descriptive in nature, and provides the basis for generating hypotheses and experiments to understand how communities work

Species Richness

The number of distinct species present within a community

Species Evenness

The relative abundance of each species present within a community

Species Diversity

The variety of species in a community, considering both species richness and species evenness.

Taxonomic affinity

Describes species within a community that share similarities in taxonomy or form a clade

Guild

A group of species that use the same resources (Subsets of species)

eg. Bats, honeybees, and hummingbirds are all pollinators

Functional Group

Describes species within a community that provide a similar service or function within the community (Subsets of species)

Biodiversity

Describes the diversity of the community and can be reflected at many different levels

Species Accumulation Curves

Species richness plotted as a function of the total number of individuals counted

Membership in a community depends on:

The regional species pool

Environmental conditions

Species interactions

These factors act as “filters,” which exclude or include species in particular communities

The Regional Species Pool

Provides an upper limit on the number and types of species that can be present in a community

Environmental conditions

A species may be able to get to a community but be unable to tolerate the environmental or abiotic conditions.

eg. a lake might not support organisms that require fast-flowing water

Species Interactions

Coexistence with other species is also required for community membership.

• Other species may be required for growth, reproduction, or survival.

• Species may be excluded by competition, predation, parasitism, or disease.

Interaction Strength

Magnitude of the effect of one species on the abundance of another species is measured by removing one species (the interactor species) from the community and observing the effect on the other species (the target species)