Adaptation

Adaptation is any attribute of an organism -- morphological, physiological, or behavioural -- that enables it to survive and reproduce successfully in its habitat. Faced with variation and stress in their abiotic surroundings, organisms cope in essentially two contrasting ways. Some are able to regulate: through physiological and behavioural mechanisms, they maintain a fairly constant internal environment (homeostasis) -- a steady body temperature, a steady osmotic concentration of body fluids, and so on -- despite changes outside. All birds and mammals are capable of this kind of regulation, known respectively as thermoregulation and osmoregulation. Others simply conform: most animals and plants cannot maintain a constant internal state, so their body temperature (or, in aquatic animals, the osmotic concentration of their body fluids) changes along with the surrounding environment -- such organisms are called conformers. …