A short history
This book is a critical look at current competition theory, which constitutes a significant fraction of theoretical ecology. My general view of the purpose of ecological theory is similar to that expressed by Michel Loreau (Loreau, 2010, p.
268): ‘It is my firm belief that ecological theory should be both a guide for basic research and a guide for action’. It is likely that very few professional ecologists would dispute Loreau’s statement. Given the unprecedented rates of loss of species and natural biological communities, most ecologists hope that ecological theory will provide practical advice on altering the dynamics of natural populations undergoing undesired changes, such as declines towards extinction. Certainly, as Loreau states, it ‘should’ do so. Nevertheless, ecological theory in its present state has largely failed to make predictions or contribute to plans that could help to avert the collapse of ecological systems. This book will examine the reasons for these shortcomings by focusing on competition theory, a subset of ecological theory. Competition theory is central to most of the other branches of ecological theory and has a particularly long history in the field. Investigating its current state and why it has not progressed more rapidly may provide more general insights for ecological theory and for ecology as a whole.Understanding ecology’s current state requires some history. Ecology, the scientific study of the distribution and abundance of living organisms, developed out of natural history. Natural history had provided an accounting and description of the organisms in natural communities long before ecology arose as a scientific discipline. Ecology sought to explain the properties of those communities and predict their future. Accounting for or predicting either the population size or geographic range of almost any species on Earth represents a major challenge.
It was clear to some biologists in the early twentieth century that the natural history knowledge of that period would not be sufficient to answer most of the major questions about abundance, even for a single species. Because distributions and abundances are constantly changing, those biologists recognized that the mathematics of dynamical systems was clearly important for understanding ecology. As the scope and magnitude of human impactsCompetition Theory in Ecology. Peter A. Abrams, Oxford University Press. © Peter A. Abrams (2022).
DOI: 10.1093∕oso∕9780192895523.003.0001 on natural systems have escalated, mathematical models have become increasingly important tools to provide insights and predictive power.
Ecological theory began to appear in the 1920s, some of it spurred by applied questions in fisheries. However, in spite of a few developments over the next three decades, largely in fisheries, pest control, and human demography, a mathematical framework for understanding ecological communities was still largely absent from ecological literature in the 1960s. At that point quantitative ecology started to receive renewed attention from biology departments in universities in North America. In part this was because of the perceived insufficiency of the theory that existed at the time; it certainly had a poor track record in applied fields like fisheries management. The 1960s were also a time of expansion in biology departments and increased interest in ecology among the general population. Now most major universities have a department devoted to ecology, evolution, and behaviour, and many have one or more faculty members engaged in developing ecological theory. The scientific literature on ecology and evolution has expanded enormously.
In spite of this expansion of the field as a whole, my impression is that theory in ecology has not lived up to its promise at the time I started graduate work half a century ago. It has definitely not provided the type of predictive and explanatory power that I and many others at that time were expecting to develop quickly.
This book will examine both the history and the current state of theory on one of the major types of ecological interactions, competition. Competition theory provides a case study of some of the problems in developing theory in ecology more generally. It was the central interaction studied by many of the ecologists who were responsible for the revival of theoretical ecology in the 1960s and early 1970s. Focusing on competition theory can still be justified, because an adequate understanding of competition either requires or implies a good understanding of all other interactions.Competition occurs within and between species. It therefore has an effect on the abundance of every organism. Competition between species sets limits on the number of species that can coexist. Competition between individuals within a species determines the maximum abundance of a species and how rapidly it is approached. Within-species competition is also the driver of natural selection and its resulting evolutionary change. Competition is at least part of the mechanism behind divergent selection that leads to speciation. Thus, competition is responsible for generating new species as well as for limiting the number of species that can be present locally. All of these considerations contributed to making competition a central focus of the mathematical approaches to ecological interactions that developed in the 1960s and 70s. Competition had been a major area of interest for decades before this, with major arguments in the 1940s and 1950s about how important it was in determining the abundance of species (see Hutchinson, 1978).
Most ecologists who have studied this interaction have come to the study of competition with some preconceptions. All humans have some personal experience with competition. It often begins with issues such as, ‘Who gets to play with a favourite toy?', and continues throughout life, involving money and various other needed or desired ‘items' that are in limited supply. Most of economics is about competition, and a Web of Knowledge search for articles about ‘competition’ from the past five years yields more publications from economics than from ecology. Thus, most students in an introductory ecology class have some preconceived notions about competition. In spite of (or perhaps because of) this, the meaning of competition in ecology has remained something of a grey area. To address this confusion, the next chapter in this book is devoted to documenting the history of definitions and arguing for one based solely on shared use of resources that influence population growth.
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