Blackwell Reference Online

Extract

Ecology is the study of organisms in relation to their environment – not merely the physical components of the environment but the other organisms whose lives overlap theirs, particularly those on which they feed and for which they in their turn provide sustenance. The central thread of ecological analysis is the food chain, which extends from the “primary producers” which fix solar energy into variously extended pathways whose links are herbivores, predators, parasites, and saprophytes. Such chains are often elaborately intertwined. The physical environment may be considerably modified by side-effects of the food chain; most importantly, the atmospheric oxygen on which all respiration depends is a product of photosynthesis by plants and algae. Because the manner in which organisms obtain their sustenance from one another exerts a powerful selective pressure, the evolution of the Earth's biosphere has produced organisms that exploit the feeding habits of other organisms in order to secure their own reproductive fortunes; thus, plants routinely produce seeds with edible packaging, or use nectar to inveigle insects into becoming pollen-disseminators. Such “symbiotic” patterns of mutual dependency are a further augmentation of the complexity and intricacy of ecosystems. Although the word was coined by Ernst Haeckel in 1873 ecology did not become established as a formal discipline until ... log in or subscribe to read full text