Colonisation or colonization is the spread and development of an organism in a new area or habitat. Colonization comprises the physical arrival of a species in a new area, but also its successful establishment within the local community. In

ecology Ecology () is the natural science of the relationships among living organisms and their Natural environment, environment. Ecology considers organisms at the individual, population, community (ecology), community, ecosystem, and biosphere lev ...

, it is represented by the symbol ''λ'' (lowercase

lambda Lambda (; uppercase , lowercase ; , ''lám(b)da'') is the eleventh letter of the Greek alphabet, representing the voiced alveolar lateral approximant . In the system of Greek numerals, lambda has a value of 30. Lambda is derived from the Phoen ...

) to denote the long-term intrinsic growth rate of a population. Surrounding theories and applicable process have been introduced below. These include dispersal, colonisation-competition trade off and prominent examples that have been previously studied. One classic

scientific model Scientific modelling is an activity that produces models representing empirical objects, phenomena, and physical processes, to make a particular part or feature of the world easier to understand, define, quantify, visualize, or simulate. It ...

biogeography Biogeography is the study of the species distribution, distribution of species and ecosystems in geography, geographic space and through evolutionary history of life, geological time. Organisms and biological community (ecology), communities o ...

posits that a species must continue to colonize new areas through its life cycle (called a '' taxon cycle'') in order to persist. Accordingly, colonisation and extinction are key components of

island biogeography Insular biogeography or island biogeography is a field within biogeography that examines the factors that affect the species richness and diversification of isolated natural communities. The theory was originally developed to explain the pattern ...

, a theory that has many applications in ecology, such as

metapopulations A metapopulation consists of a group of spatially separated populations of the same species which interact at some level. The term metapopulation was coined by Richard Levins in 1969 to describe a model of population dynamics of insect pests in a ...

. Another factor included in this scientific model is the competition-colonisation trade off. This idea goes into the driving factors of colonisation through many species that all share a need to expand.

Scale

Colonisation occurs on several scales. In the most basic form, as

biofilm A biofilm is a Syntrophy, syntrophic Microbial consortium, community of microorganisms in which cell (biology), cells cell adhesion, stick to each other and often also to a surface. These adherent cells become embedded within a slimy ext ...

in the formation of communities of

microorganism A microorganism, or microbe, is an organism of microscopic scale, microscopic size, which may exist in its unicellular organism, single-celled form or as a Colony (biology)#Microbial colonies, colony of cells. The possible existence of unseen ...

s on surfaces. This microbiological colonisation also takes place within each animal or plant and is called

microbiome A microbiome () is the community of microorganisms that can usually be found living together in any given habitat. It was defined more precisely in 1988 by Whipps ''et al.'' as "a characteristic microbial community occupying a reasonably wel ...

. In small scales such as colonising new sites, perhaps as a result of

environmental change Environment most often refers to: __NOTOC__ * Natural environment, referring respectively to all living and non-living things occurring naturally and the physical and biological factors along with their chemical interactions that affect an organism ...

. And on larger scales where a species expands its

range Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to i ...

to encompass new areas. This can be through a series of small encroachments, such as in

woody plant encroachment Woody plant encroachment (also called woody encroachment, bush encroachment, shrub encroachment, shrubification, woody plant proliferation, or bush thickening) is a natural phenomenon characterised by the area expansion and density increase of ...

, or by long-distance dispersal. The term range expansion is also used.

Dispersal

Dispersion in biology is the dissemination, or scattering, of organisms over periods within a given area or over the Earth. The dispersion of species into new locations can be inspired by many causes. Often times species naturally disperse due to physiological adaptations which allows for a higher survival rate of progeny in new ecosystems. Other times these driving factors are environmentally related, for example

global warming Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes ...

disease A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical condi ...

competition Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indi ...

predation Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

. Dispersion of different species can come in many forms. Some prime examples of this is flight of species across long distances, wind dispersal of plant and fungi progeny, long distance of travel in packs, etc.

Competition-colonisation trade-off

The competition-colonisation trade-off refers to a driving factor that has a large influence over diversity and how it is maintained in a community. This is considered a driving factor because all species have to make a decision to entertain competition with others in the community or disperse from the community in hopes of a more optimal environment. This can span from available nutrient sources, light exposure, oxygen availability, reproduction competition, etc.. These trade offs are critical in the explanation of colonisation and why it happens. Pioneer species colonization leading to primary sucession

Pioneer species colonization leading to primary sucession

Use

The term is generally only used to refer to the spread of a species into new areas by ''natural'' means, as opposed to ''unnatural''

introduction Introduction, The Introduction, Intro, or The Intro may refer to: General use * Introduction (music), an opening section of a piece of music * Introduction (writing), a beginning section to a book, article or essay which states its purpose and g ...

or translocation by humans, which may lead to

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

Colonisation events

Large-scale notable pre-historic colonisation events include:

Arthropods

*the colonisation of the Earth's land by the first animals, the

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

s. The first fossils of land animals come from

millipede Millipedes (originating from the Latin , "thousand", and , "foot") are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derive ...

s. These were seen about 450 million years ago.

Humans

* the

early human migration Early human migrations are the earliest Human migration, migrations and expansions of Homo, archaic and modern humans across continents. They are believed to have begun approximately 2 million years ago with the early expansions of hominin ...

and colonisation of areas outside Africa according to the recent African origin paradigm, resulting in the extinction of Pleistocene megafauna, although the role of humans in this event is controversial.

Birds

* the colonisation of the

New World The term "New World" is used to describe the majority of lands of Earth's Western Hemisphere, particularly the Americas, and sometimes Oceania."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: ...

by the cattle egret and the little egret * the colonisation of

Britain Britain most often refers to: * Great Britain, a large island comprising the countries of England, Scotland and Wales * The United Kingdom of Great Britain and Northern Ireland, a sovereign state in Europe comprising Great Britain and the north-eas ...

by the little egret * Iguana iguana Portoviejo 04

the colonisation of western North America by the

barred owl The barred owl (''Strix varia''), also known as the northern barred owl, striped owl or, more informally, hoot owl or eight-hooter owl, is a North American large species of owl. A member of the true owl family, Strigidae, they belong to the genus ...

* the colonisation of the East Coast of

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

by the Brewer's blackbird * the colonisation-westwards spread across

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

of the collared dove * the spread across the eastern USA of the house finch * the expansion into the southern and western areas of

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

by the Hadeda Ibis

Reptiles

* the colonisation of

Anguilla Anguilla is a British Overseas Territories, British Overseas Territory in the Caribbean. It is one of the most northerly of the Leeward Islands in the Lesser Antilles, lying east of Puerto Rico and the Virgin Islands and directly north of Sa ...

by Green iguanas following a rafting event in 1995 * the colonisation of

Burmese python The Burmese python (''Python bivittatus'') is one of the largest species of snakes. It is native to a large area of Southeast Asia and is listed as Vulnerable on the IUCN Red List. Until 2009, it was considered a subspecies of the Indian pyth ...

s into the Florida Everglades. The release of snakes came from the desire to breed them and sell them as exotic pets. As they grew people became unable to care for the animals and began to release them into the Everglades.

Dragonflies

*the colonisation of Britain by the small red-eyed damselfly

Moths

*the colonisation of Britain by Blair's shoulder-knot

Land Vertebrates

* The colonisation of Madagascar by land-bound vertebrates.

Plants

* The colonisation of ''

Pinus A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. ''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as c ...

'' species through wind dispersion.