Populations, metapopulations, and the open-closed dilemma: the conflict between operational and natural population concepts

In this essay, we review and discuss what we consider the problems and misunderstandings related to the definition and identification of natural populations, as well as the importance of populations as real units in ecology. We focus on how choosing inappropriate spatial scales may drastically change the way a population is defined. Our aim is to determine the influence of the different views of the population concept on our perception of the dynamics of natural systems. In particular, we propose that populations are real biological units that have a precise and unambiguous meaning when they are analyzed at their proper spatial scale.