Glossary for Human Ecology

Index

Adaptation:

a condition or character which afford fitness to a species in a particular environment.

Adaptive radiation:

evolutionary divergence of members of a single phyletic line into many different niches.

Allele:

one of two or more different chemical codes possible for a given gene. Offers variation in a given trait.

Alien:

a non-native species, especially one introduced to some part of the world through human action.

Altitudinal zonation:

the sorting of plant and animal species according to elevation in response to differences in temperature and precipitation patterns.

Annual:

a plant with a lifespan of one year.

Artificial selection:

the process in which humans direct the differential reproductive success of individuals in a breeding population.

Australopithecine:

a member of the hominid genus Australopithicus; a pre-human genus dating from 4.0 to 1.0 million years ago and restricted to Africa.

Australopithecus afarensis:

early pre-human ancestor to modern Man. Known from the Rift Valley of Eat Africa, 3.9 to 3.0 million years ago. "Lucy" is a member of this species, which is named for the Afar triangle in Ethiopia where fossils of the species were first unearthed. Believed to be an omnivore.

Australopithecus boisei:

a robust form of Australopithecus from East Africa adapted to a vvegetarian diet; known from 2.6 to 1 million years ago, when it apparently shared the savanna with Homo habilis.

Biennial:

a plant with a lifespan of two years. Often only flowers and sets seed during the second year.

Biodiversity:

The total variation in life, including the number of species, the degree of genetic variation within species, the different types of ecosystems, and the all ecosystem functions.

Biogeography:

the science that studies the distribution of life, past and present.

Biomass:

weight of living matter, usually given as weight per unit area

Biome:

one of the largest recognizably distinct ecosystems on earth; the plant and animal communities and associated soils that are characteristic of a given regional climate type.

Biotic potential:

the maximum rate of reproduction possible in a species as determined by such factors as age of sexual maturity, number of offspring produced per reproductive event; number of times a year reproduction occurs; reproductive lifespan of females; age and sex structure of population.

Chromosome:

rod-shaped bodies in the nuclei of cells that consist of a string of genes and maintain the structure or arrangement of the genetic code (DNA).

Climax community:

the final stage in ecological succession; a mature community that will persist through time and is seen as in balance with the regional climate.

Cline:

a series of contiguous populations that exhibit gradual and continuous change of character in response to some environmental gradient.

Clone:

individual produced by asexual reproduction and hence genetically identical to parent.

Colonization:

the establishment of a population in a place formerly unoccupied by that species. Colonization implies successful reproduction in the new area, not simply the presence of a species there.

Community:

A group of populations of different species occupying a given place at a given time that are viewed as interdependent. An aggregation of interacting species. Sometimes used to refer to only the assemblage of populations of a particular class of organisms, such as the bird community, the herb community, and so forth.

Congeners:

refers to species belonging to the same genus

Conspecific:

refers to individuals or populations of the same species

Consumer:

a population that obtains energy by eating other organisms; an herbivore, carnivore, or omnivore

Detritus food chain:

the pathway of energy flow that begins with dead or partially decayed organic matter and continues through the organisms that feed upon detritus (detritivores); may account for approximately 90 percent of the energy flow in terrestrial ecosystems. [See grazing food chain.]

Dispersal:

the transport of propagules beyond the limits of a species' distribution area

Distribution area:

the geographic range of a taxon.

• Allopatric: literally, "other country"; refers to distribution areas of different taxa that do not overlap.
• Disjunct: refers to a fragmented distribution area with two or more geographically separated ranges.
• Relict: a distribution area that is a mere remnant of a formerly wider range.

Domestication:

Ecology:

the science that studies the relationships between organisms and their environment. "The study of the structure and function of nature" (Odum, 1971--Fundamentals of Ecology).

Ecosystem:

A community of species together with the surrounding environment that function together as a coherent unit to maintain a flow of energy and to acquire, store, and recycle nutrients.

Ecosystem services:

activities that help to maintain an ecosystem but are not directly part of energy flows and nutrient cycles. Examples include pollination, dispersal, and population regulation.

Edaphic factor:

A permanent or nearly permanent condition of the substrate that influences the types of plants that grow in an area. For example, substrates may be permanently or seasonally waterlogged, droughty, deficient in essential nutrients, extremely thin, and so forth.

Endemic:

describes a taxon restricted to and native to a particular area.

Environment:

the totality of physical, chemical, and biotic conditions surrounding an organism

Environmental resistance:

those factors of the environment which prevent reproduction or inhibit development of a species and hence limit the extent (or determine the borders) of its distribution area.

Evolution:

a change in the allele frequencies within a population

Fauna:

the animal life of a given area. A list of all species of animals found in a given area

Feeding strategy:

the way an organism captures energy. Includes food items, search patterns, habitats utilized, diurnal and seasonal foraging patterns.

Feral:

describes a species that was once tamed or domesticated and has since reverted to a free-roaming life in the wild.

Fitness:

the measure of a species ability to survive and reproduce

Flora:

the plant life of a given area. A list of all species of plants found in a given area., often listing diagnostic features.

Founder Principle:

a few individuals starting a new population may represent an atypical sample of the parent species' gene pool. This "sampling error" leads to the founder effect: rapid changes in allele frequencies in the colonizing population and divergence from the parent population.

Function:

refers to action, how something works. An ecosystem functions to maintain a flow of energy and cycling of nutrients.

Gene:

the segment of DNA at a particular locus on a particular chromosome that controls production of proteins and enzymes and influences the development of a specific trait.

Gene flow:

the transfer of genes (actually, alleles) from one population to another.

Gene pool:

the totality of genetic information in a given population at a given time

Genetic drift:

allele frequency changes (evolution) in populations caused by random events rather than by natural selection, especially the effects of sampling error on the gene pool of small populations.

Genotype:

the genes (or alleles) present in an individual

Geographic isolation:

the separation of a population from the rest of its species due to some physical barrier, such as a mountain range, an ocean, or great distance.

Grass:

a member of the Graminae family of flowering plants.

Grazing Food Chain

The pathway by which energy in an ecosystem flows from producers through consumers.

Gross Primary Productivity:

the rate at which a plant or ecosystem converts light energy to chemical energy. The rate at which a plant or ecosystem fixes carbon.

Hominid:

any member of the family Hominidae, the family of man. The two most generally accepted genera in the family are Australopithecus and Homo.

Homo habilis

the oldest recognized species in the genus Homo, known only from East Africa from about 2.0 million years ago. Believed to be the first hominid to use stone tools.

Homo erectus

the first species in the genus Homo to disperse out of Africa. A highly successful species that survived from 1.5 million years ago to perhaps 100,000 BP in some places. Believed to have been able to control fire, the tool that allowed it to leave the tropics. Several subspecies are recognized: H. e. olduvaiensis, the African subspecies; H. e. pekinensis, so-called Peking Man associated Zhoukoudien cave in China by 500,000 years ago; and H. e. erectus, so-called Java Man--the skull of a 700,000 year old specimen found in the Indonesian island of Java was the first H. erectus specimen found.

Homo sapiens

Anatomically modern man, although this designation (without the subspecific moniker sapiens is usually reserved for archaic forms. Some scientists recognize several subspecies, including H. s. mapaensis in Asia and H. s. heidelbergensis in Europe and Africa. Homo sapiens is believed to have originated in Africa by 500,000 BP and spread across the Old World. A third subspecies, Homo sapiens neanderthalis, represents a highly specialized form adapted to the rigors of glacial Europe and western Asia that was extinct by 30,000 BP.

Homo sapiens sapiens

Us. Modern human beings. Probably arose in Africa around 150,000 years ago. The only form of Homo known to have dispersed to the New World. Occurred in Australia by 50,000 BP; North America probably by 18,000 BP, and known from Tierra del Fuego, South America, by 11,000 BP.

Individual variation:

phenotypic diversity within a population. Each individual is genetically different from every other in a sexually reproduction population giving rise to a variety of phenotypes.

Inorganic

Refers to minerals and gases that are not part of or formed by living organisms. Chemistry other than that of organic materials.

K-strategy

The reproductive strategy wherein energy is invested a few, large offspring that require considerable parental care. (opposite = r-strategy)

Landscape:

a mosaic of repeated ecosystems in a given geographic area. The land is heterogeneous, but there are structural and functional relationships among the matrix and the various patches and corridors.

Landscape Ecology:

the study of patterns of ecosystems of a given area and the interactions among those various ecosystems.

Locus:

a specific place or location on a given chromosome. The genetic information encoded there is a gene.

Native:

a species which is a natural member of a biotic community. An indigenous species. (The term implies that humans were not involved in the dispersal or colonization of the species.)

Natural Selection:

the process in which evolution occurs by differential survival and reproductive success among individuals in a genetically variable population

Neotony:

a genetic change in a species that influences the rate of maturity so that the organism retains a juvenile appearance even when a sexually mature adult. This is a common occurrence in the domestication of animals--and some argue is significant in the evolution of humans, especially females.

Net Primary Production (NNP):

the rate at which a plant or an ecosystem produces new plant biomass by growth and reproduction. NNP is equal to gross primary production minus respiration.

Niche:

the total requirements and tolerances of a species; its way of life, including how it traps energy and otherwise uses resources in its habitat. According to the Competitive Exclusion Principle no two species can occupy the same niche at the same time in the same ecosystem.

Organic

In chemistry, refers to complex compounds of carbon. The molecules contained in and produced by living organisms, including carbohydrates, proteins, amino acids, fats, DNA, and so forth.

Perennial:

a plant that lives more than two years

Phenotype:

the totality of characteristics of an individual: the expression of the genotype.

Photosynthesis

The process by which light energy from the sun is converted into chemical energy by chlorophyll-bearing organisms (cyanobacteria and green plants). The chemical process involves the synthesis of carbon dioxide and water in the presence of sunlight and chlorophyll to produce organic compounds (e.g., glucose) and oxygen. Photosynthesis is also the first step of the carbon cycle, as carbon as well as light is "fixed" in organic compounds.

Pioneer species:

a species that is an early occupant of newly created or disturbed areas. A member of the earliest communities in ecological succession.

Population:

the individuals of a given species that occupy the same locality and form the actual interbreeding group in that location. A group of two or more populations which regularly exchange genes is known as a metapopulation..

Producer

In ecology, any organism that "fixes" light energy into usable chemical energy; the green plants.

Propagule:

In animals, the minimum number of individuals of a species capable of colonizing a new area. This may be fertilized eggs, a mated female, a single male and a single female, or a whole group of organisms depending upon the biological and behavioral requirements of the species. In plants, a propagule is whatever structure functions to reproduce the species: a seed, spore, stem or root cutting, etc.

r-Strategy

A reproductive strategy in which energy is invested a multitude of offspring that receive little or no parental care.

Reproductive isolation:

a condition in which interbreeding between populations is prevent by intrinsic factors of the species themselves.

Reproductive strategy:

the way in which a species allocates or budgets energy to produce viable offspring. Energy is diverted into actual offspring and into parental care. [Compare r-Strategy and K-strategy.]

Respiration:

The use of oxygen to break down organic compounds metabolically to release chemical energy: Oxygen plus organic molecules produce carbon dioxide, water vapor, and heat.

Secondary productivity:

the rate at which herbivores produce new biomass through growth and reproduction. As a rule of thumb, only 10 percent of plant matter is converted to herbivore tissue. The remainder is either not ingested, not digested (and thus passed through an animal to be eliminated as feces) or released as heat.

Speciation:

the process by which new species arise. The process by which discontinuities between populations occur due to the development of mechanisms creating the reproductive isolation of one population from the other.

• Allopatric speciation: species formation that occurs during geographic isolation of populations. Generally believed to be the most common way in which new species arise, especially among the higher animals.
• Sympatric speciation: the formation of new species without geographic isolation; the acquisition of reproductively isolating mechanism among individuals coexisting in the same area. Not infrequent in plants.

Subclimax community:

A final, persistent community in ecological succession that is determined by some factor other than the regional climate. Usually this factor is type of disturbance (such as fire or grazing) or an edaphic condition (such as a waterlogged substrate, a low nutrient substrate; or a droughty substrate.

Ecological succession:

(according to the original theory): the development of an ecosystem through a predictable series of communities until a final, stable community (the climax community) in balance with the regional climate is attained. In its original form, the theory implied that each community altered the habitat and prepared it for invasion by the next, succeeding community.

• Primary succession: succession of communities that begins on a new barren substrate--one devoid of life--such newly exposed bedrock, a sand dune, or a new glacial lake.
• Secondary succession: the progression of communities where a pre-existing climax community has been disturbed or destroyed and a soil is already developed on the site. "Old field succession."

Structure:

the organization of the ecosystem in terms of trophic levels. Also may refer to the physical arrangement or spatial patterns of the components of an ecosystem, especially the plant life. Includes growthforms, number of canopy layers, degree of cover, distribution patterns of species within the ecosystem (patches, for example).

System:

A set of interconnected and interacting parts that function as a unit

Taxon:

any one of the levels in the taxonomic hierarchy:

• Kingdom: One of the major subdivisions of life; based upon basic similarities in cell structure. Five kingdoms are currently recognized: Monera, Protista, Fungi, Animalia, and Plantae.
• Phylum: A subdivision of a kingdom encompassing all forms of life with the same distinctive body plan. [plural = phyla].
• Class: a higher taxon consisting of one or more orders and distinct from other taxa of similar rank
• Order: a higher taxon consisting of one or more families and distinct from other taxa of similar rank.
• Family: a taxonomic level including one or more genera of common phylogenetic origin and distinct from taxa of the same rank. [The Latin names of animal families end in "-idae".]
• Genus: a taxonomic category including one or more species with a presumed recent common ancestor.
• Species: groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups. The lowest taxonomic rank and presumably only real taxonomic unit in nature.
• Subspecies: a geographically defined aggregate of local populations which differ phenotypically from other such subdivisions of a species in other geographic areas.

Taxonomy:

the science of classifying and identifying organisms. The modern classification of organisms reflects their presumed phylogeny.

Trophic level:

position in the food chain as determined by the number of steps removed from the initial fixing of the sun's energy. Terrestrial ecosystems commonly exhibit only four levels: producers, first level consumers (the herbivores), second level consumers (the carnivores), and third level consumers (the top carnivores).

Trophic pyramid:

the graphic representation of ecosystem structure based on feeding or trophic levels. The producers form the base of the pyramid and subsequent steps diminish in size depicting the lessening of usable energy at higher trophic levels. Units may be calories, biomass, or number of individuals.