Everything about Biogeography totally explained
Biogeography is the study of the distribution of
biodiversity over
space and
time. It aims to reveal where organisms live, at what abundance, and why.
The patterns of species distribution at this level can usually be explained through a combination of historical factors such as
speciation,
extinction,
continental drift,
glaciation (and associated variations in
sea level, river routes, and so on), and
river capture, in combination with the area and isolation of landmasses (geographic constraints) and available energy supplies.
History
The scientific theory of biogeography grows out of the work of
Alfred Russel Wallace and other early evolutionary scientists. Wallace studied the distribution of flora and fauna in the Malay Archipelago in the
19th century. With the exception of Wallace and a few others, prior to the publication of
The Theory of Island Biogeography by
Robert MacArthur and
E.O. Wilson in
1967 the field of biogeography was seen as a primarily historical one and as such the field was seen as a purely descriptive one.
MacArthur and Wilson changed this perception, and showed that the species richness of an area could be predicted in terms of such factors as habitat area, immigration rate and extinction rate. This gave rise to an interest in
island biogeography. The application of island biogeography theory to
habitat fragments spurred the development of the fields of
conservation biology and
landscape ecology.
Classic biogeography has been expanded by the development of
molecular systematics, creating a new discipline known as
phylogeography. This development allowed scientists to test theories about the origin and dispersal of populations, such as
island endemics. For example, while classic biogeographers were able to speculate about the origins of species in the
Hawaiian Islands, phylogeography allows them to test theories of relatedness between these populations and putative source populations in
Asia and
North America.
Palaeobiogeography
Paleobiogeography goes one step further to include
paleogeographic data and considerations of
plate tectonics. Using molecular analyses and corroborated by
fossils, it has been possible to demonstrate that
perching birds evolved first in the region of
Australia or the adjacent
Antarctic (which at that time lay somewhat further north and had a temperate climate). From there, they spread to the other
Gondwanan continents and Southeast Asia - the part of
Laurasia then closest to their origin of dispersal - in the late
Paleogene, before achieving a global distribution in the early
Neogene (Jønsson & Fjeldså 2006). Not knowing the fact that at the time of dispersal, the Indian Ocean was much narrower than it's today, and that South America was closer to the Antarctic, one would be hard pressed to explain the presence of many "ancient" lineages of perching birds in Africa, as well as the mainly South American distribution of the
suboscines.
Classification
Biogeography is a synthetic science, related to
geography,
biology,
soil science,
geology,
climatology,
ecology and
evolution.
Some fundamentals in biogeography are
- evolution (change in genetic composition of a population)
- extinction (disappearance of a species)
- dispersal (movement of populations away from their point of origin, related to migration)
- range and distribution
- endemic areas
- vicariance
Further Information
Get more info on 'Biogeography'.
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