Biogeography does more than ask Which species? and Where. It also asks Why? and what is sometimes more crucial, Why not?. 
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.
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 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.
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 is 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.
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
- Ecozone (biogeographic region or biogeographical realm)
- Ecological land classification
- Gravity model of migration, pertaining to Distance decay
- Zoogeographic province
- Floristic province
- Continental drift
- Tectonic plates
- Alfred Russel Wallace
- Charles Darwin
- Miklos Udvardy
- Important publications in biogeography
Notes and References
- Martiny JBH et al. Microbial biogeography: putting microorganisms on the map Nature: FEBRUARY 2006 | VOLUME 4
- The song of Dodo: Island Biogeography in an age of extinctions by David Quammen 1996 Pub Scribner, New York ISBN 0-684-80083-7
- This work expanded their 1963 paper on the same topic.
- This applies to British and American academics; landscape ecology has a distinct genesis among European academics.
- Jønsson, Knud A. & Fjeldså, Jon (2006). Determining biogeographical patterns of dispersal and diversification in oscine passerine birds in Australia, Southeast Asia and Africa. Journal of Biogeography 33(7): 1155–1165. (HTML abstract)
- Dansereau, Pierre (1957). Biogeography: An Ecological Perspective. New York City: Ronald Press Company. ISBN 0826023304.
- MacArthur, Robert H. (1972). Geographic Ecology. New York: Harper & Row.
- International Biogeogaphy Society
- Systematic & Evolutionary Biogeographical Society
- Early Classics in Biogeography, Distribution, and Diversity Studies: To 1950
- Early Classics in Biogeography, Distribution, and Diversity Studies: 1951-1975
- Some Biogeographers, Evolutionists and Ecologists: Chrono-Biographical Sketches