Animals, microorganisms and plants live in environments to which they have become adapted through millions of years of evolution; they often have to respond to changes which are biotic or abiotic in nature, and, increasingly, to anthropogenic perturbations which have resulted in global environmental change; in understanding how organisms respond and interact with 1 another in their natural and man-made habitats, a wide spectrum of approaches is employed in environmental biological research ranging from molecular biology to population biology and community ecology.