Glossary for Biogeography
NOTE: Terms are arranged according to the following subject
categories: biogeography, ecology, evolution, landscape ecology, and taxonomy.
This should not be taken to mean that any term is limited in use or definition
to a particular discipline; the arrangement is a pedagogical device to
help the beginning student in biogeography to make associations among various
words and processes. Each term also may be accessed through the index
at the end of this document.
- 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.
- the science that studies the distribution of life, past and present.
- 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.
- the transport of propagules beyond the limits of a species' distribution
- Distribution area:
- the geographic range of a taxon.
- Allopatric: literally, "other country";
refers to distribution areas of different taxa that do not overlap.
- Circumboreal: found throughout the high
latitude forests of the northern hemisphere; that is, in North America
- Circumpolar: refers to a distribution
area that circles either the north pole or south pole.
- Cosmopolitan: worldwide, or nearly so,
- Disjunct: refers to a fragmented distribution
area with two or more geographically separated ranges.
- Pantropical: refers to a distribution
area that extends through the tropics (that is generally between 23°
30' S and 23° 30' N latitude).
- Relict: a distribution area that is a mere
remnant of a formerly wider range.
- literally, "same country"; refers to distribution areas of
different species that overlap.
- Ecogeographic rule:
- one of the statements from 19th century naturalists recognizing correlations between the morphology of warm blooded animals (mammals and birds) and climatic and/or latitudinal gradients.
- describes a taxon restricted to and native to a particular area.
- describes a species that was once tamed or domesticated and has since
reverted to a free-roaming life in the wild.
- Life Zone:
- belts of vegetation that are similar in structure and species composition
in both latitudinal and elevational expressions.
- 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.)
- 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.
- Relict (taxon):
- a taxon that remains from an earlier geologic time when environmental conditions were different than at present.
- Refers to species that occupy similar ecological niches but in geographic
isolation from each other. Implies a phylogenetic relationship existing
between the two species.
- a plant with a lifespan of one year.
- a plant with a lifespan of two years. Often only flowers and sets seed
during the second year.
- 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.
- 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.
- a soft- or non-woody-stemmed vine that clasps the stems or branches
of trees and shrubs to raise its foliage and flowers above the ground;
a type of growthform.
- 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.
- Cushion plant:
- low growing mat formed by tightly massed individuals of the same species
of plant. Generally associated with tundra or high alpine communities.
- nonvascular plants such as lichens and mosses that make up the ground
or surface layer of vegetation.
- Dispersal (sensu ecology):
- the transport of propagules away from the parent.
- a) the total number of species present;
b) some index which incorporates both the number of species and the relative
abundance of each.
- 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.
- 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).
- 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.
- 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.
- an annual plant with an extremely short lifespan measured in a few
weeks or very few months; characteristic growthform of desert forbs.
- a plant which uses a rock or host plant merely as a place of residence
and obtains its moisture and nutrients directly from the air; an air plant.
A type of growthform.
- the totality of physical, chemical, and biotic conditions surrounding
- 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.
- a small, upright soft-stemmed or non-woody plant with broadleaves;
the growthform of many common wildlfowers
- a group of communities in a single region or continent with similar
physiognomy (structure) and related climatic and environmental conditions.
One of several regional or continental expressions of a given biome.
- refers to action, how something works. In the case of ecosystem functions
we look at photosynthesis, nutrient cycling, population control, dispersal
mechanisms, temporal patterns of flowering , breeding, dormancy, and so
- an herb with grass-like morphology; a growthform typified by true grasses
(Graminae) and by sedges (Cyperacaeae).
- a member of the Graminae family of flowering plants.
- the overall morphology of a plant species, including its stature, leaf
type, and habit. The most basic growtforms are trees, shrubs, forbs, and
graminoids; but there are many more specialized growthforms such as epiphytes,
lianas, and stem succulents.
- a member of the Ericaceae or heather family. Usually leathery-leaved
shrubs preferring acidic or low-nutrient substrates and often tolerant
- any non-woody vascular plant; a category of plants including both forbs
and graminoids. Hence the term "herbaceous" layer .
- Landscape Ecology:
- the study of patterns of ecosystems of a given area and the interactions
among those various ecosystems.
- a woody-stemmed vine. Lianas are rooted in the substrate and use trees
or shrubs as support; often their leaves and flowers reach the canopy of
layer of the vegetation. A type of growthform.
- the total requirements and tolerances of a species; its way of life,
including how it traps energy and otherwise uses its habitat or microhabitat.
- A plant without chlorophyll that obtains its nutrients by tapping into
the branches, stems or roots of living green plants
- a plant that lives more than two years
- A desert shrub with a long trap root that enables the plant to avoid
reliance on rainwater by tapping into groundwater.
- Pioneer species:
- a species that is an early occupant of newly created or disturbed areas.
A member of the early stage communities in ecological succession.
- the individuals of a given species that occupy the same locality and
form the interbreeding group in that location. A group of two or more populations
that regularly exchange genes is known as a metapopulation..
- a growthform in which the leaves are arranged in concentric circles
or whorls around a central bud.
- a plant lacking chlorophyll that obtains its nutrients from dead organic
matter. The bacteria and fungi of decay are examples, but there are also
flowering plants like the white Indian pipes of eastern US Temperate Broadleaf
Deciduous Forests or the giant Rafflesia of the Indo-Malyasian formation
of the Tropical Braodleaf Evergreen Forest that are saprophytes.
- any member of the Cyperacaeae, a family of flowering plants that in
their growthform resemble grasses.
- a plant that begins life as an epiphyte in the canopy of a forest and
sends its roots down the trunk of a host tree and into the substrate. The
roots may form a thick woody net around the host's trunk, but it is apparently
the foliage of the strangler that eventually kills the host by blocking
sunlight from the latter's leaves. A type of growthform found in tropical
- 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). Structure may also refer to the organization of
the ecosystem in terms of trophic levels.
- a plant that is able to store water in its tissues and then withdraw
it during times of drought. Water storage tissue may be found in the stem,
leaves, or roots depending on the species. Stem succlulents, leaf succulents,
and root succulents are types of growthforms.
- a hummock of grasses or sedges bound together by their roots
- a species that volunteers in artificially modified habitats and is
considered undesirable by people. The same species may occur elsewhere
in a wild state, or even in cultivation.
Weedy habit refers to the propensity of certain species to disperse
easily and widely and to colonize disturbed habitats.
- a plant well adapted to withstand prolonged drought. The typical xerophyte
is a deciduous shrub with tiny leaves and a shallow root system that etends
well beyond the crown of the shrub.
- a condition or character which afford fitness to a species in a particular
- Adaptive radiation:
- evolutionary divergence of members of a single phyletic line into many
- one of two or more different chemical codes possible for a given gene.
Offer variation in a given trait.
- a series of contiguous populations that exhibit gradual and continuous
change of character in response to some environmental gradient.
- 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).
- phenotypic similarity in distantly related (or unrelated) forms, presumably
in response to similar selective pressures.
- a change in the allele frequencies within a population
- the measure of a species ability to survive and reproduce
- 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.
- 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
- Genetic drift:
- allele frequency changes in populations caused by random events rather
than by natural selection, especially the effects of sampling error on
the gene pool of small populations.
- 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.
- Individual variation:
- phenotypic diversity within a population.
- a specific place or location on a given chromosome. The genetic information
encoded there is a gene.
- the totality of characteristics of an individual: the expression of
- Phyletic gradualism:
- the belief that evolution (and especially speciation) occurs over considerable
time through a slow accumulation of new alleles and changing allele frequencies.
- the evolutionary history of a taxon. The graphic representation of
a phylogeny is called a phylogenetic tree.
- Punctuated equilibrium:
- the belief that evolution proceeds by spurts of change interspersed
with long periods of stasis (genetic stability) where selection favors
- Reproductive isolation:
- a condition in which interbreeding between populations is prevent by
intrinsic factors of the species themselves.
- 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.
- the line or zone formed by the edges of two adjacent ecosystems.
- a linear strip of habitat type that differs from that on either side
- that part of an ecosystem near the perimeter that is influenced by
the environment of the adjacent ecosystem so that it differs in some characteristics
from the center of the ecosystem. Edge effect refers to changes
in species composition, distribution and/or abundance found in the edge
relative to the interior.
- 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.
- the background land use or vegetation in a landscape: that ecosystem-type
which is most extensive so that others appear as patches or corridors within
- a nonlinear habitat type that differs from the surrounding vegetation.
- in cladistics, a group with a common set of shared derived characteristics
persumed inherited from a common ancestor
- a methodology for reconstructing evolutionary relationships of taxa,
both living and extinct, by using the distribution of shared derived characters.
- in cladistics, a graphic depiction of evolutionary relationships based
on shared derived characters
- refers to species belonging to the same genus
- refers to individuals or populations of the same species
- Derived (character):
- in cladistics, a feature shared among members of smaller groups or
clades that is believed to have evolved at a later date than primitive
features. Also called advanced.
- the animal life of a given area. A list of all species of animals found
in a given area
- the plant life of a given area. A list of all species of plants found
in a given area., often listing diagnostic features.
- 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 recognized: Monera, Protoctista, 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
- Subspecies: a geographically defined aggregate
of local populations which differ phenotypically from other such subdivisions
of a species in other geographic areas.
- Primitive (character):
- in cladistics, a character shared among and defining members of a large
group or clade and believed to have arisen early in the group's evolution.
- the science of classifying and identifying organisms. The modern classification
of organisms reflects their presumed phylogeny.
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Created September 7, 1996 by Susan L. Woodward. Last
updated September 29, 1997 by slw.
The URL for this page is http://www.runet.edu/~swoodwar/CLASSES/GEOG235/glossary.html