Search Results

This chapter begins the story by exploring how the idea of extinction emerged as a biological concept in the nineteenth century. Despite the current ubiquity of the term, extinction challenged earlier notions of the stability of nature and the benevolence of a creator god. When naturalists first determined that the geological record revealed that a great many species which had formerly existed have become extinct, new ideas about the "balance of nature" had to be developed that could account for extinction as a process contributing to overall natural stability. Two of the central characters in this chapter are Georges Cuvier, who was responsible for confirming the empirical fact of extinction and who developed a "catastrophic" model of geo-historical change, and Charles Lyell, whose view that extinction is an ordinary feature of natural history had an enormous influence on later understandings of the relationship between extinction and biological diversity.

Greeks first sought rational explanations of nature and rejected mythological explanations. Their earliest natural philosophy was simplistic, but their process of conjecture and refutation enabled them to develop more sophisticated explanations. Natural philosophy influenced other aspects of Greek thinking: medicine included the idea that health is a balance of humors, that disease is humoral imbalance, and that adverse climate causes humors to become unbalanced; the traveler Herodotus explained that predatory animals have fewer offspring than their prey to avoid eating all their prey and then starving. That discussion was supplemented by Plato's assertion that all species are endowed with the means for survival, and this resulted in an implicit concept of the balance of nature. Aristotle established an Athenian school that combined natural philosophy and information about nature to create sciences of zoology and botany, the latter associated with his successor, Theophrastus. Romans combined Greek teachings with Roman uncritical information, which resulted in Pliny the Elder's work on natural history.

This chapter focuses on the moose and their wilderness ecosystem at Isle Royale, an island of the Great Lakes located in the northwest of Lake Superior. It first considers the migration of moose around 1900 to one that was then and still is one of the best examples in the world of a wilderness undisturbed by human influence —what many would call the forest primeval. It then looks at the arrival of wolves on the island and whether Isle Royale had reached a steady state in which a balance of nature was achieved in a constant number of moose and wolves and in a constant abundance of the plants the moose ate. It suggests that this balance of nature is consistent with the assumptions of the theory of ecology at the time. The chapter also discusses the notion of stability in relation to the moose population at Isle Royale, along with predator-prey interactions that were exemplified by moose and wolves on the island.

The non-equilibrium dynamics of biological invasions has revived the debate on the balance of nature and mechanisms for population regulation. Invasive species in novel environments, whether experiencing the quasi-equilibrium of halted expansion during the lag phase or undergoing fast expansion to fulfil the opportunity niche, face a multitude of stabilizing and destabilizing forces that affect their population dynamics—from positive (Allee effects) and negative density dependence to rapidly shifting niches during invasion; these have major effects on population variability and spatial dynamics. The temporal and spatial dynamics are also intertwined, which means that the spatial structures of species distributions are potentially indicative of the invasiveness and population trends of target species. Time-series analysis for depicting the temporal population dynamics can be extended to capture the spatial synchrony dynamics of multiple local populations. Spatial autoregressive models further advance species distribution models to unveil the drivers of non-equilibrium dynamics of invasive species.

This chapter examines the view that considers nature as a biosphere by focusing on the moose and their wilderness ecosystem at Isle Royale, an island of the Great Lakes, as well as their symbiotic relationship with bacteria. It first describes the moose's rumen as a miniature model of the biosphere before discussing some of the classic scientific arguments about the influence of life on the global environment. In particular, it looks at the views of Adam Sedgwick and Sir Charles Lyell. It then assesses the notion that life is an integral part of very long-term global geologic processes and explains how biological evolution has led to global changes in the environment. It also analyzes three schools of thought about a balance of nature at the global level: that the biosphere is in a steady state; that life acts as Earth's thermostat, requiring and creating constant conditions; and that the biosphere is always changing, and life is changing with it, beyond the ability of life to act as Earth's thermostat. The chapter concludes with some philosophical reflections about nature's hierarchies in space and time.