Essential Knowledge 4.B.3

Interactions between and within populations influence patterns of species distribution and abundance.

Interactions between populations affect the distributions and abundance of populations. Competition, parasitism, predation, mutualism and commensalism can affect population dynamics. Relationships among interacting populations can be characterized by positive and negative effects, and can be modeled mathematically (predator/prey, epidemiological models, invasive species). Many complex symbiotic relationships exist in an ecosystem, and feedback control systems play a role in the functioning of these ecosystems. Note: Specific symbiotic interactions are beyond the scope of the course and the AP Exam.

A population of organisms has properties that are different from those of the individuals that make up the population. The cooperation and competition between individuals contributes to these different properties.

Species-specific and environmental catastrophes, geological events, the sudden influx/depletion of abiotic resources or increased human activities affect species distribution and abundance. Examples include:

• Loss of keystone species
• Kudzu
• Dutch elm disease

Students should be able to:

LO 4.19 use data analysis to refine observations and measurements regarding the effect of population interactions on patterns of species distribution and abundance.