9: The Ecology of Populations

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Learning Objectives

Define what ecologists mean by a population of organisms and the focus and scope of the science of population ecology.
Introduce the key features of populations studied by ecologists, wildlife biologists, and conservation biologists -- such as size, density, and range -- and the field methods used to study them.
Outline common patterns of population change, such as growth, extirpation, extinction, and cycles.
Introduce the concepts of population regulation, density independence, and density dependence.

Summary

Populations are one of the major levels of biological organization, and "population thinking" has played a key role in ecology and evolutionary biology since Darwin. Currently, many researchers and natural resource managers are trained as population ecologists, from academics who study basic questions in evolutionary ecology to government scientists who determine catch limits for fisheries. In this chapter we define what populations are, their key features which are considered by basic and applied ecologists, and the techniques used out in the field to study populations. We'll also introduce key ecological concepts which will be elaborated on in the next chapter, including population regulation, density independence, and density dependence.