Glossary Endemic Describing a species or other taxonomic group that is restricted to or occurs only in a specified geographic location or region The actual size of the area is arbitrary (an endemic species might be found only in North America or only on a small island) A member of such a species or group Endemic language One of the languages that are restricted to a single country and, like their species counterparts, hold a high percentage of the unique traits in human language as a whole Endemism The fact of a species or other taxonomic group being found only in a specific location of limited size, rather than being widely distributed Also, endemicity Endocrine disruptor A chemical that interferes with the endocrine system, the means of chemical communication (mainly performed by hormones) within an organism Endogenous Inside; occuring within a system Specifically, occurring within an organism or a population of organisms Contrasted with EXOGENOUS Endogenous forces Forces within a population that affect the dynamics of the population Endogenous process A process that emerges from biotic and abiotic interactions internal to the system of interest Examples include vegetation growth and succession, dispersal of organisms within a landscape, and topographic influences on microclimate Some human activities may be considered endogenous (e.g., crop rotation systems) if they are well established and responsive to local needs Endogenous risk The concept that private citizens and public servants have some control over the set of probabilities and outcomes that define the relevant states of the world Endoparasite A parasite living inside a host Endophyte A fungus or other parasitic organism residing or growing within plant tissue Such an organism is endophytic The portion of such an organism that is embedded inside the host tissue Endosperm Nutritive storage tissue in the seeds of most angiosperms Endosymbiont An organism living in a long-term association inside a host organism for their mutual benefit; e.g., methanogenic bacteria that live inside an aerobic protozoa and utilize waste H2 produced by the host) Such an association is endosymbiotic Endotherm An animal whose body temperature is mainly regulated by its own metabolism and varies only slightly with external conditions; e.g., mammals Endothermic Describing animals who regulate their body temperature mainly through internal metabolic means; in popular use, ‘‘warm-blooded.’’ Endothermy A method of body temperature control in which the animal modifies its metabolic rate to achieve the desired temperature, largely independent of the ambient temperature Contrasted with ECTOTHERMY Enemy release hypothesis The idea that alien species have a better chance of establishing and becoming dominant when released from the negative effects of natural enemies that, in their native range, lead to high mortality rates and reduced productivity 499 Energetic web A food web depiction that quantifies the amount of energy (or material) that flows across the links joining species Energy A fundamental physical concept, defined classically as the capacity to perform work Potential energy is this capacity stored as a consequence of its position, structure, shape, or state Kinetic energy is this capacity as manifested in the motion of matter The joule (J) is the common SI unit of energy, where J equals the amount of energy required to increase the temperature of g of water by 11 K The use of this capacity by humans to perform useful functions, such as heating or cooling, lighting, transportation, powering devices and tools, and so on See also RENEWABLE ENERGY; NON-RENEWABLE ENERGY; INDUSTRIAL ENERGY; TRADITIONAL ENERGY Energy balance The difference between incoming solar energy and outgoing terrestrial radiation for the Earth as a whole The relative energy flows into and out of a living system, such as an ecosystem or an individual organism Also, energy budget Energy efficiency A measure of the performance of an energy system First Law efficiency (based on the first law of thermodynamics) equals the ratio of desired energy output to the energy input Second Law efficiency (based on the second law) equals the ratio of the heat or work usefully transferred by a system to the maximum possible heat or work usefully transferable by any system using the same energy input Energy sprawl An increase in the agricultural land area required for the production of dedicated biofuel crops in place of food crops, natural and semi-natural habitats, and other land uses, occurring directly from land-use change or indirectly due to biofuel-related market conditions Engineer See ECOSYSTEM ENGINEER ENSO El Nin˜o Southern Oscillation Entropy A measure of the degree of disorder, or randomness, in a given system at a given time; greater entropy means less energy available to work The entropy of an isolated system cannot decrease when the system undergoes a change Environment The entirety of the biological world and its physical surroundings The living and non-living surroundings of a particular organism Environmental Relating to the natural environment and the impact of human activity on it Describing efforts to protect the viability and diversity of the natural world Environmental ethics The philosophical discipline that describes and specifies proper human relationships with the natural world Environmental filter(ing) Constraints on the presence and abundance of species in local communities or regional species pools, due to abiotic conditions Environmental impact assessment (EIA) A formalized process, including public consultation, in which all relevant environmental consequences of a project are identified and assessed before authorization is given to proceed Environmental Kuznets curve See KUZNETS CURVE Environmental stress An action, agent, or condition that impairs the structure or function of a biological system Environmental sustainability The fact of maintaining ecosystem conditions that will sustain the biosphere now and into the future The complex of environmental, economic, social, and cultural systems necessary to accomplish this