Welden C W, Slauson W L
Q Rev Biol. 1986 Mar;61(1):23-44. doi: 10.1086/414724.
The intensity of competition is a physiological concept, related directly to the well-being of individual organisms but only indirectly and conditionally to their fitness, and even more indirectly to the evolution of populations and the structure of communities. The importance of competition is primarily an ecological and evolutionary concept, related directly to the ecology and fitness of individuals but only indirectly to their physiological states. The intensity of competition is not necessarily correlated with the intensities of predation, disturbance, abiotic stress, or other ecological processes. The importance of competition is necessarily relative to the importances of other processes. Intensity refers primarily to the process of present competition, whereas importance refers primarily to the products of past competition. The distinction between the intensity and the importance of competition clarifies two long-standing ecological debates. Some ecologists have proposed that competition is greater in more stressful habitats, others the opposite, and still others that no such relationship exists. Evidence cited to refute or support these positions often confuses intensity and importance. Distinguishing between them focuses questions more sharply and indicates what sorts of new evidence should be sought. The more widely known debate over the prevalence of competition as an agent of community structure is a debate about the importance of competition, but evidence about the intensity of competition has often been used by both sides. We argue that intensity and importance need not be correlated, and so measurements of the intensity of competition are not directly relevant to this debate. This distinction also generates testable hypotheses and suggests directions for research. For example, we hypothesize that competition can be unimportant even if it is very intense: no such hypothesis is possible unless importance is distinguished from intensity. We discuss the application of these ideas to methods and theories used to study competition, ecological communities, and the evolution of competitive ability. We advocate a research approach that presumes multiple, interacting causes, including competition, affecting community structure, and we show how the distinction between intensity and importance helps to make this feasible.
竞争强度是一个生理学概念，直接关系到个体生物的健康，但只是间接地且有条件地关系到它们的适合度，甚至更间接地关系到种群的进化和群落的结构。竞争的重要性主要是一个生态学和进化概念，直接关系到个体的生态学和适合度，但只是间接地关系到它们的生理状态。竞争强度不一定与捕食、干扰、非生物胁迫或其他生态过程的强度相关。竞争的重要性必然相对于其他过程的重要性。强度主要指当前竞争的过程，而重要性主要指过去竞争的结果。竞争强度和重要性之间的区别澄清了两个长期存在的生态学争论。一些生态学家提出，在压力更大的栖息地竞争更激烈，另一些人则持相反观点，还有一些人认为不存在这样的关系。用来反驳或支持这些观点的证据常常混淆了强度和重要性。区分它们能更清晰地聚焦问题，并指出应该寻求何种新证据。关于竞争作为群落结构动因的普遍程度的更著名争论是关于竞争重要性的争论，但双方经常使用关于竞争强度的证据。我们认为强度和重要性不一定相关，因此竞争强度的测量与这场争论没有直接关联。这种区别还产生了可检验的假设，并为研究指明了方向。例如，我们假设即使竞争非常激烈，它也可能不重要：除非将重要性与强度区分开来，否则不可能有这样的假设。我们讨论了这些观点在用于研究竞争、生态群落和竞争能力进化的方法和理论中的应用。我们提倡一种研究方法，该方法假定包括竞争在内的多种相互作用的原因会影响群落结构，并且我们展示了强度和重要性之间的区别如何有助于使其可行。
