Chapter 4: The Living World: Ecosystems and Biodiversity Terms

10% Rule

the rule that in a food chain, only about 10% of the energy is transferred from one level to the next

abiotic

related to factors or things that are separate and independent from living things; nonliving

abyssal zone

the deepest region of the ocean, marked by extremely cold temperatures and low levels of dissolved oxygen, but high levels of nutrients because of the decaying plant and animal matter that sinks down from the zones above

ammonification

the production of ammonia or ammonium compounds in the decomposition of organic matter, especially through the action of bacteria

anaerobic

without oxygen

aquatic life zones

ecosystems in aqueous environments

assimilation

the process in which plants absorb ammonium (NH3), ammonia ions (NH4+), and nitrate ions (NO3) through their roots

autotrophs

producers; organisms that can produce their own organic compounds from inorganic compounds; they use energy from the Sun or from the oxidation of inorganic substances

barrier island

a long, relatively narrow island running parallel to the mainland, built up by the action of waves and currents and serving to protect the coast from erosion by surf and tidal surges

bathyal zones

the middle region of the ocean, characterized by less density of organisms because it does not receive enough light to support photosynthesis

benthic zone

the surface and sub-surface layers of the river-, lake-, pond-, or streambed, characterized by very low temperatures and low oxygen levels

biodiversity

the number and variety of organisms found within a specified geographic region, or ecosystem, or the variability among living organisms, including the variability within and between species and within and between ecosystems

biogeochemical cycle

the complex cycles through which nutrients such as carbon, oxygen, nitrogen, phosphorus, sulfur, and water move through the environment

biological extinction

true extermination of a species; no individuals of this species are left on the planet

biomes

ecosystems based on land

biotic

living or derived from living things

chapparal

scrub forest or shrubland; a biome characterized by moderate precipitation, shallow or infertile soil, small trees with large, hard evergreen leaves, and spiny shrubs

chemotrophs

autotrophic bacteria that use chemosynthesis to produce energy in anaerobic environments

climax community

a stable, mature community in a successive series that has reached equilibrium after having evolved through stages and adapted to its environment

coastal zone

ocean zone consisting of the ocean water closest to land, usually defined as between the shore and the end of the continental shelf (the edge of the tectonic plate); characterized by abundant sunlight and oxygen

combusted

burned

commensalism

symbiotic relationship in which one organism benefits while the other is neither helped nor hurt

commercial (economic) extinction

a few individuals exist but the effort needed to locate and harvest them is not worth the expense

community

formed from populations of different species occupying the same geographic area

competition

the relationship that exists when two individuals–of the same species or of different species–compete for resources in the same environment

competitive exclusion

the process that occurs when two different species in a region compete and the better adapted species wins

coniferous forest (taiga)

a biome characterized by moderate precipitation, acidic soil, and coniferous trees

consumers

organisms that must obtain food energy from secondary sources, for example, by eating plant or animal matter

coral reef

an erosion-resistant marine ridge or mountain consisting chiefly of compacted coral together with algal material and biochemically deposited magnesium and calcium carbonates

cultural services

use of nature for science and education, therapeutic and recreational uses, and spiritual and cultural uses

deciduous forest

a biome characterized by adequate precipitation, rich soil with high organic content, and hardwood trees

decomposers

organisms that consume dead plant and animal material–the process of decomposition returns nutrients to the environment

denitrification

the process by which specialized bacteria (mostly anaerobic bacteria) convert ammonia to NO3, NO2, and N2, which are released back into the atmosphere

deserts

biomes characterized by extremely low precipitation, coarse sandy soil, and cactus and other low-water adapted plants

detritivores

organisms that derive energy from consuming nonliving organic matter, such as dead animals or fallen leaves

ecological extinction

the condition in which there are so few individuals of a species that the species can no longer perform its ecological function

ecological succession

the transition in species composition of a biological community, often following ecological disturbance of the community; the establishment of a biological community in any area virtually barren of life

economic extinction

a few individuals exist but the effort needed to locate and harvest them is not worth the expense

ecoregions

smaller regions within ecosystems that share similar physical features

ecosystem

a system of interconnected elements; a community of living organisms and its environment

ecosystem services

benefits that humans receive from the ecosytem in nature when they function properly

ecotones

regions where different biomes overlap

ecozones (ecoregions)

smaller regions within ecosystems that share similar physical features

edge effect

the condition in which there is greater species diversity and biological density at ecosystem boudaries than there is in the heart of ecological communities

energy pyramid

the structure obtained if we organize the amount of energy contained in producers and consumers in an ecosystem by kilocalories per square meter, from largest to smaller

epilimnion

the uppermost and thus the most oxygenated layer of freshwater

estuary

the part of the wide lower course of a river where its current is met by the tides

euphotic zone

the photic, upper layers of ocean water; the euphotic zone is the warmest region of ocean water and has the highest levels of dissolved oxygen

eutrophication

warm water becoming overly enriched with minerals and nutrients to the point that excessive growth of algae and other phytoplankton occurs (an algal bloom)

evaporation

conversion of a liquid in a gas (vapor)

evolution

change in the genetic composition of a population during successive generations as a result of natural selection acting on the genetic variation among individuals and resulting in the development of new species

evolutionary fitness

the better-adaptedness of individual organisms for their environment that allows them to live and reproduce, ensuring that their genes are part of their population’s next generation

exchange pool

a site where a nutrient sits for only a short period of time

extinction

the death of an entire species; permanent inactivity

food chain

a succession of organisms in an ecological community that constitutes a continuation of food energy from one organism to another as each consumers a lower member and, in turn, is preyed upon by a higher member

food web

a complex of interrelated food chains in an ecological community

fundamental niche

the niche a species would have if there were no competition

Gause’s principle

states that no two species can occupy the same niche at the same time, and that the species that is less fit to live in the environment will either relocate, die out, or occupy a smaller niche

gene pool

the total genetic makeup of a population

generalist

a species that has a broad niche, is highly adaptable, and can live in varied habitats

genetic drift

the random fluctuation in the frequency of the appearance of a gene in a small, isolated population, presumably owing to chance, rather than natural selection

grasslands

a biome characterized by moderate precipitation, rich soil, and sod-forming grasses

Gross Primary Productivity

the amount of sugar that the plants produce in photosynthesis

groundwater

any water that comes from below the ground (from wells or from aquifers)

habitat

the area or environment where an organism or ecological community normally lives or occurs

habitat fragmentation

when the size of an organism’s natural habitat is reduced, or when development occurs that isolates a habitat or part of one

heterotroph

an organism that cannot synthesize its own food and is dependent on complex organic substances for nutrition

hypolimnion

the lower, colder, and denser layer of freshwater

indicator species

species that are used as a standard to evaluate the health of an ecosystem

indigenous species

species that originate and live, or occur naturally, in an area or environment

interspecific competition

competition between individuals of different species

intraspecific competition

competition between individuals of the same species

invasive species

introduced, non-native species

keystone species

a species whose very presence contributes to an ecosystem’s diversity and whose extinction would consequently lead to the extinction of other forms of life

Law of Conservation of Matter

states that matter can neither be created nor destroyed

Law of the Minimum

states that living organisms will continue to live, consuming available materials until the supply of these materials is exhausted

Law of Tolerance

describes the degree to which living organisms are capable of tolerating changes in their environment

limiting factor

any factor that controls a population’s growth

limnetic zone

the surface of open ocean water; the region that extends to the depth that sunlight can penetrate

littoral zone

ocean zone beginning with the very shallow water at the shoreline and extending to the depth at which rooted plants stop growing

macroevolution

large-scale patterns of evolution within biological organisms over long periods of time

mangrove swamps

coastal wetlands (areas of land covered in fresh water, salt water, or a combination of both) found in tropical and subtropical regions

microevolution

small-scale evolutionary changes over relatively short periods of time

mutualism

a symbiotic relationship in which both species benefit

natural selection

the process by which, according to Darwin’s Theory of Evolution, only the organisms best adapted to their environment tend to survive and transmit their genetic characteristics in increasing numbers to succeeding generations, while those less adapted tend to be eliminated

Net Primary Productivity (NPP)

the amount of energy that plants pass on to the community or herbivores in an ecosystem; the amount of sugar that the plants produce in photosynthesis minus the amount of energy the plants need for growth, maintenance, repair, and reproduction

niche

the total sum of a species’ use of the biotic and abiotic resources in its environment

nitrification

the process in which soil bacteria convert ammonium (NH4+) to a form that can be used by plants: nitrate, or NO3-

nitrogen fixation

the conversion of atmospheric nitrogen into compounds, such as ammonia, by natural agencies or various industrial processes

parasitism

a symbiotic relationship in which one member is helped by the association and the other is harmed

phosphorus cycle

the cycle through which phosphorus moves through the environment in different forms

photosynthesis

the process in green plants and certain other organisms by which carbohydrates are synthesized from carbon dioxide and water using light as an energy source: most forms of photosynthesis release oxygen as a byproduct

phylogenetic tree

a branching diagram used to model evolution and describe the evolutionary relationships between species

pioneer species

the organisms that take root and adapt to the conditions of a habitat in the first stages of ecological succession

population

a group of organisms of the same species that live in the same area

precipitation

water that condenses in the atmosphere and falls to the Earth’s surface in liquid or solid form

predation

when one species feeds on another

predator

a species that feeds on another species

prey

a species that’s subject to predation by another species

primary consumers

organisms that consume producers (plants and algae)