Understanding ecological concepts: The role of laboratory systems

Ecology is a disparate discipline with studies ranging from the highly abstract to the highly applied. Understanding ecological concepts often involves the use of theoretical models, laboratory studies, and/or field studies, all of which exist on a continuum, with laboratory experiments often considered to be somewhere between abstract theoretical models and the field studies of the natural world. Laboratory systems have many appealing features such as ease of culturing, manipulation, minimal sampling difficulties, repeatability, and quantifiable resource supply, but there are more fundamental reasons for using laboratory microcosms. Long-term population (time series) studies are the cornerstone for testing hypotheses about the processes and mechanisms of population regulation, limitation, and persistence. However, field studies of population ecology suffer from a double jeopardy. While ecological time series are at the heart of population ecological research, they are often of insufficient length and are unreplicated which makes statistical inferences often weak or even impossible. Laboratory experiments provide one solution to this jeopardy by allowing well-replicated, long-term experiments to be done under controlled environmental conditions. The use of laboratory or model systems in ecology has been widely advocated as a plausible and realistic approach to understanding the processes and mechanisms underpinning ecological systems (Kareiva, 1989; Lawton, 1995). In this review, we discuss the use of laboratory microcosms in understanding ecological concepts focusing particularly on the ideas central to population ecology. However, our rationale and approach is equally applicable to evolutionary and genetic experiments, and can be more widely applied in the design and implementation of field-based ecological experiments. We begin by outlining the philosophy and rationale for laboratory microcosm experiments. We emphasize the role of appropriate model selection and choice as the underlying approach for integrating ecological theory and experiments. Following this, we review the historical contributions that laboratory experiments have made to our understanding of a number of core ecological concepts. In the final section, we conclude by examining the prospects for the use of laboratory systems in ecological research. © 2005 Elsevier Inc. All rights reserved.