Essential Knowledge 4.A.5

Communities are composed of populations of organisms that interact in complex ways.

The structure of a community is measured and described in terms of species composition and species diversity.

Mathematical or computer models are used to illustrate and investigate population interactions within and environmental impacts on a community.

Examples include:

• Predator/prey relationships spreadsheet model
• Symbiotic relationship
• Graphical representation of field data
• Introduction of species
• Global climate change models

Mathematical models and graphical representations are used to illustrate population growth patterns and interactions. Reproduction without constraints results in the exponential growth of a population. A population can produce a density of individuals that exceeds the system’s

resource availability. As limits to growth due to density-dependent and density-independent factors are imposed, a logistic growth model generally ensues. Demographics data with respect to age distributions and fecundity can be used to study human populations.

Students should be able to:

LO 4.11 justify the selection of the kind of data needed to answer scientific questions about the interaction of populations within communities.

LO 4.12 apply mathematical routines to quantities that describe communities composed of populations of organisms that interact in complex ways.

LO 4.13 predict the effects of a change in the community’s populations on the community.