Chapter 2. Population Ecology

Learning Objectives

Pre-Lab—Factors Affecting Population Growth
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General Purpose

Conceptual

  • Gain an understanding of the factors that impact populations.
  • Gain an understanding of the factors that impact and cause change in ecosystems.

Procedural

  • Gain experience setting up controlled population ecology experiments.
  • Gain experience graphing.

General Purpose

In your travels through the area in which you live, within the state of Louisiana, across the United States, or internationally, surely you have noticed changes in scenery (types of vegetation present or contour of the landscape) and/or climate. These casual observations are directly related to the biological science of ecology. This discipline within biology is the study of how organisms interact with their environment. The environment includes biotic factors (other organisms: predators, parasites, competitors, mates) and abiotic factors (water, light, nutrients, temperature, soil type, topography).

Ecological investigations can be approached from many different levels by examining: individual organisms, populations, communities, and ecosystems. Population ecology includes the study of the distribution and abundance of a population of a given species in a specified area at a specified time, whereas community ecology includes the study of all organisms that inhabit a given area. The ecosystem ecology includes all of the communities of organisms plus the abiotic factors in an area. Many community and ecosystem level processes use populations as the fundamental unit.

The size of a population and whether it is increasing or decreasing have a large impact on these processes. Population growth is often shown as logistic growth (see Figure 4-1).

Figure 4-1. A graph showing the logistic growth model for a population with a finite carrying capacity.

Logistic growth occurs when exponential growth is limited by the carrying capacity of the ecosystem.

View the following video for information for a discussion of various aspects of population growth.

In this lab you will examine the impact of an abiotic factor on the growth of a population. Since monitoring the growth of a population is something that happens over time you will be required to make periodic measurements to assess the growth of the population in your experiment.

Pre-Lab Quiz

Proceed to the Pre-Lab Quiz