Colonisation (biology)

For the same species living closely together, see Colony (biology).

Colonisation or colonization is the process in biology by which a species spreads to new areas. Colonisation often refers to successful immigration where a population becomes integrated into a community, having resisted initial local extinction.

One classic model in biogeography posits that species must continue to colonize new areas through its life cycle (called a taxon cycle) in order to achieve longevity. Accordingly, colonisation and extinction are key components of island biogeography, a theory that has many applications in ecology, such as metapopulations.

Scales

Colonisation occurs on several scales:

• biofilm scales: the formation of communities of microorganisms on surfaces.
• small scales: colonising new sites, perhaps as a result of environmental change.
• large scales: where a species expands its range to encompass new areas. This can be via a series of small encroachments or by long-distance dispersal. The term range expansion is often used.

Means

The term is generally only used to refer to the spread into new areas by natural means, as opposed to introduction or translocation by humans, which are called introduced species and sometimes becoming invasive species.

Species colonisation events

Some large-scale notable colonisation events in the 20th Century are:

Birds

• the colonisation of the New World by the cattle egret and the little egret.
• the colonisation of Britain by the little egret
• the colonisation of western North America by the barred owl,
• the colonisation of the East Coast of North America by the Brewer's blackbird
• the colonisation-westwards spread across Europe of the collared dove

Dragonflies

• Dragonfly - the colonisation of Britain by the small red-eyed damselfly

Moths

• Moth - the colonisation of Britain by Blair's shoulder-knot

See also

• Colony (biology)
• Invasive species - habitat colonisation, from human introduction