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 ...

, geodispersal is the erosion of barriers to gene flow and

biological dispersal Biological dispersal refers to both the movement of individuals (animals, plants, fungi, bacteria, etc.) from their birth site to their breeding site ('natal dispersal') and the movement from one breeding site to another ('breeding dispersal' ...

(Lieberman, 2005.; Albert and Crampton, 2010.). Geodispersal differs from vicariance, which reduces gene flow through the creation of geographic barriers. In geodispersal, the geographical ranges of individual

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

, or of whole biotas, are merged by erosion of a physical barrier to gene flow or dispersal. Multiple related geodispersal and vicariance events can be mutually responsible for differences among populations. As these geographic barriers break down, organisms of the secluded ecosystems can interact, allowing gene flow between previously separated species, creating more biological variation within a region. A well documented example of geodispersal in between continental ecosystems was the Great American Biotic Interchange (GABI) between the terrestrial faunas and floras 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 ...

and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

, that followed the formation of the

Isthmus of Panama The Isthmus of Panama, historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North America, North and South America. The country of Panama is located on the i ...

about 3 million years ago. Between 69 and 47 million years ago, the Thulean Land Bridge facilitated gene flow by allowing bees from the

Old World The "Old World" () is a term for Afro-Eurasia coined by Europeans after 1493, when they became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia in the Eastern Hemisphere, previously ...

to travel to 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: ...

, an example of geodispersal from the Old World to the New World. Another example was the formation of the modern

Amazon Amazon most often refers to: * Amazon River, in South America * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon (company), an American multinational technology company * Amazons, a tribe of female warriors in Greek myth ...

River Basin about 10 million years ago, which involved the merging of previously isolated Neotropical fish faunas to form what is now the most species-rich continental

aquatic ecosystem An aquatic ecosystem is an ecosystem found in and around a body of water, in contrast to land-based terrestrial ecosystems. Aquatic ecosystems contain communities of organisms—aquatic life—that are dependent on each other and on their environ ...

on Earth (Oberdorff et al., 2011).

Notes and references

{{Reflist Biogeography