GLOSSARY Abiotic Referring to the non-living components of an ecosystem; i.e., the chemical and physical environment Ablation A direct transfer of water molecules from ice crystals to the vapor phase, without transition through the liquid phase Abundance The number of individuals of a given species in a region, area, or site Specifically, the average parasite load of an entire host population (including uninfected individuals) Abyssal Referring to the deepest part of the ocean Abyssal plain A large, relatively flat area of the ocean bottom, typically 2000 to 6000 m in depth Acceptance A behavior pattern in which hosts treat brood parasitic eggs as if they were their own eggs Accidental epiphyte A plant that normally grows terrestrially but that occasionally grows to maturity on or in a tree Acclimation Another term for ACCLIMATIZATION (see next) Specifically, a process of acclimatization that occurs in a controlled, experimental setting, such as a laboratory Acclimatization Reversible physiological or morphological changes that an organism experiences in response to changing environmental conditions Such physiological changes enable the organism to tolerate (acclimatize to) the new environmental conditions Accounting price See SHADOW PRICE Accretionary Accumulating; describing a gradual increase or growth, as of sand on a beach Acetylcholinesterase (AChE) The enzyme responsible for breaking down the neurotransmitter acetylcholine (ACh) at nerve synapses, thereby preventing hyperexcitation of cholinergic pathways in the nervous system The target of organophosphate and carbamate insecticides Acid deposition Anthropogenic acidification of terrestrial and freshwater ecosystems by (primarily) sulfuric acid, derived from sulfur dioxide produced by burning oil and coal and deposited in rain and snow (acid rain), directly as particles (dry deposition) and as cloud droplets Acid neutralizing capacity (ANC) The amount of strong acid that is required to decrease the pH of water to a defined chemical end point Acid neutralizing capacity is measured in units of meq lÀ1 It is a measure of the ability of water to neutralize inputs of strong acids Acidification The process of soil or water becoming more acidic, with a loss of base cations (calcium, magnesium, potassium) and an increase in hydrogen and aluminum ion concentrations, resulting in losses of plant biodiversity and dominance by acid-tolerant species Acidophilic Acid-loving; describing organisms that prefer or require a low pH environment Such an organism is an acidophile Acidophytic, Acidophyte Alternate form of ACIDOPHILIC, ACIDOPHILE (see previous) Acid-sensitive Describing an area with low supply rates of acid-neutralizing basic cations These areas generally occur in Encyclopedia of Biodiversity, Volume high-elevation forest regions and are characterized by shallow soil Acquisition costs The costs of acquiring property rights to a parcel of land This can be total (if the land and title are sold to a conservation agent) or partial Partial transfers of property rights include short-term rental, conservation easements, and contracts between conservation agents and land owners who exchange money for land management that enhances conservation value Active restoration A process of actively assisting a system in recovery beyond simply removing the disturbance Acute Describing an exposure to an environmental stress that is brief in relation to the temporal scale of the biological system exposed Acute toxicity A damaging effect caused by a single short period of exposure to high concentrations of a pollutant Adaptation In general, characteristics or behavior patterns of an organism that suit it to its conditions of existence Specifically (under the theory of descent with modification), a derived feature of an organism that increases the survival and reproductive success of the organism by virtue of the possession of that feature Adaptationism The doctrine that all important evolutionary processes are dominated by natural selection, and that all significant biological characters increase an organism’s fitness Adaptive radiation The evolution of ecological and phenotypic diversity within a rapidly multiplying lineage Adaptive shift A change in the nature of a trait (morphology, ecology, or behavior) that enhances survival and/or reproduction in an ecological environment different from that originally occupied by the organism Adaptive syndrome A coordinated set of adaptations Additionality The achievement of environmental gains beyond what would have occurred under usual conditions Adipocytes Brown adipocytes Specialized thermogenic cells unique to mammals and probably derived from skeletal muscle, containing numerous mitochondria and small droplets of triacylglycerols Under neural and endocrine control, brown adipocytes can switch rapidly from inactivity to the highest known metabolic rate, generating heat from oxidation of fatty acids and/or glucose in mitochondria uncoupled from ATP synthesis by uncoupling proteins White adipocytes Large cells unique to vertebrates that store triacylglycerols, take up and release fatty acids, and produce various signal molecules and receptors that enable them to respond to circulating and locally acting agonists Adipose fin A small, fleshy fin without supporting spines or rays, set far back on the dorsal surface of many catfish, salmon, characins, and other groups Adipose tissue Storage tissue unique to vertebrates and best developed in tetrapods, consisting almost entirely of expandable adipocytes (see above) that contain a large droplet of triacylglycerols, along with vascular and neural tissue, and often contiguous or interchelated lymphoid tissues doi:10.1016/B978-0-12-384719-5.09009-2 481