What is Biogeography?  (under construction)

Biogeography is the science that attempts to document and understand spatial patterns of biodiversity. It is the study of distributions of organisms, both past and present, and of related patterns of variation over the earth in the numbers and kinds of living things. Where do species occur, why do they occur there, and where are the greatest concentrations?  The implications of these questions for global health are enormous. It is the species on the planet that feed us, clothe us, medicate us, and shelter us.  They produce oxygen, filter water and provide fuel.  In times of climate change, we need an immense variety of species in order offset the resulting environmental change.

In biogeography we examine several concepts.  These include species distribution and abundance (why species occur where they do),  population health and viability, endemism, the biogeography of islands, rarity, equilibium theory, speciation and species hotspots. We examine what makes one species common or even abundant, and what makes another species rare.  The causes of rarity and abundance have always been of ecological interest, and have been studied by such eminent ecologists as Mayr, Simberloff, Wilson, Keddy, and others.  Keddy's work is of particular interest to us living along the shores of the Fraser River.   He has studied wetland ecology, including shoreline species ecology, competition in plants, assembly rules and invasive species.

One of the most important concepts studied in biogeography today is centres of endemism, where species of restricted geographic range are found and where, through isolation and stability, speciation ocurs. Conservation biologists are mapping these at both a global scale and a regional scale.  Endemism occurs when a species or other taxonomic group is restricted to a particular geographic region owing to factors such as isolation or response to soil or climatic conditions. Such a taxon is said to be endemic to that region. The size of the region in this context will usually depend on the status of the taxon: thus a family will be endemic to a much larger area than a species, all other things being equal.  Centres of endemism are important because this is where speciation occurs.  It is these areas that provide, in a sense, the ecological strength that fires evolution and continuity.  It is these areas that provide species banks for maintaining ecosystem strength, and which, in turn, provide the support for human societies.

In Canada, there are also centres of endemism. These have been mapped and are discussed by Erich Haber.  These hotspots are critical to the biodiversity of our regions, and are high priority for protection.

to be continued.....
 

BIOGEOGRAPHY  CONCEPTS AND LINKS

Concept                         Definition                                                                        Links

General	Biogeography is the science that attempts to document and understand spatial patterns of biodiversity. It is the study of distributions of organisms, both past and present, and of related patterns of variation over the earth in the numbers and kinds of living things.	Biogeography.com
Biodiversity	The variety of life in all its forms, levels and combinations. Includes ecosystem diversity, species diversity, and genetic diversity (IUCN, UNEP and WWF, 1991).	Australian Biodiversity Biodiversity Profile of India Centre for biodiversity and conservation Royal Ontario Museum, Centre for Coservation and Biodiversity
Equilibirium theory	The equilibrium theory of island biogeography proposes that the number of species on islands of similar habitat in the same latitudes depends on the size and isolation of the islands, and is a balance between the rate of immigration and the rate of extinction.	Definition
Endemism	An endemic can be a species or taxon that is restricted to a geographic area and does not occur elsewhere. Endemism can occur at various spatial scales and at different taxonomic ranks.	North American Centres of Endemis
Island Biogeography	The number of species on any island reflects a balance between the rate at which new species colonize it and the rate at which populations of established species become extinct.	Theory of island biogeography Discussion
Metapopulations	A metapopulation is a system of populations characterized by one or more central, stable populations and several surrounding, fluctuating populations.  The surrounding populations may become extinct but are re-colonized by those from the central population.  As long as the number of colonizations equals the number of extinctions, a metapopulation species is stable.  Metapopulations both occur naturally and as a result of human actions. Some species naturally exist as metapopulations because the environmental factors necessary for their survival occur in patches. Examples of habitats with patchy distribution include ponds, islands, fragmented woodlots, or mountaintops.	Dynamics References

Glossary

SELECTED BIOGEOGRAPHY REFERENCES

General Biogeography

Cox, C. Barry and Peter D.  Moore.  1980.  Biogeography:  an ecological and evolutionary approach (3rd. edition).  Toronto:  John Wiley and Sons.

Dias, P.C. 1996. Sources and sinks in population biology. Trends in Ecology and Evolution 11:326-330.

Endler, John A. 1977.  Geographic Variation, Speciation and Clines.  Princeton:  Princeton University Press.  Monographs in Populations Biology : 10.

Pianka, Eric R.  1978.  Evolutionary Ecology.  New York:  Harper & Row, Publishers.
 

Island Biogeography

Burkey, T.V. 1989. Extinction in nature reserves: the effect of fragmentation and the importance of
migration between reserve fragments. Oikos 55:75-81.

Connor, E. F. and E. D. McCoy. 1979.  The statistics and biology of the species-area relationship.  American Naturalist 113:  791-833.

MacArthur, R., J. MacArthur, D. MacArthur, and A. MacArthur.  1973.  The effect of island area on population densities.  Ecology 54: 657-8.

MacArthur, R. H. and E. O. Wilson.  1967.    The theory of island biogeography.  Princeton:  Princeton University Press.

Morain, Stanly A.  1984.  Systematic and Regional Biogeography.  Melbourne:  Van Nostrand Reinhold Company.

Taylor, J. A (ed.).  1984.  Biogeography:  recent advances and future directions.  Totowa:  Barns and Noble Books.

Williamson, Mark.  1981.  Island Populations.  Oxford:  Oxford University Press.
 

Rare species

Preston, F. W.  1948.  The commonness, and rarity, of species. Ecology 29: 254-83.

Preston, F. W.  1948.  The canonical distribution of commoness and rarity.  Ecology 43:  185-215, 410-32.
 

Wetlands

Boutin, C. and P. A. Keddy. 1993. A functional classification of wetland plants. Journal of  Vegetation Science 4: 591-600. (L salicaria as a functional annual or gap coloniser)

Keddy, P.A. 1989. Competition. Chapman and Hall, London.

Keddy, P.A. and P. Constabel. 1986. Germination of ten shoreline plants in relation to seed size, soil particle size and water level: an experimental study. Journal of Ecology 74:133-141.

Keddy, P.A., L. H. Fraser, and I. C. Wisheu. 1998. The competitive response of 48  wetland plants to 7 canopy-forming species. Journal of Vegetation Science 9: 777-786.  (effects of a L. salicaria canopy on establishment of 47 other species)

Keddy, P.A., I. Wisheu, B. Shipley and C. Gaudet. 1989. Seed banks and vegetation management for conservation: Towards predictive community ecology.  IN:  M. Leck, and R. Simpson T. Parker (eds.) The Ecology of Soil Seed Banks, Academic Press, San Diego.

Shipley, B. and P.A. Keddy. 1988. The relationship between relative growth rate and sensitivity to nutrient stress in twenty-eight emergent macrophytes. Journal of Ecology 76: 1101-1110.

Shipley, B., P.A. Keddy, D.R.J. Moore and K. Lemky. 1990. Regeneration and establishment strategies of emergent macrophytes. Journal of Ecology 77: 1093-1110. (includes L. salicaria)

Toner, M, and P. Keddy. 1997. River hydrology and riparian wetlands: a predictive model for ecological assembly. Ecological Applications 7: 236-246.

Thompson, D.Q., R.L. Stuckey and E.B. Thompson. 1987. Spread, Impact and Control of Purple Loosestrife (Lythrum salicaria) in North American Wetlands. United States Department of the Interior, Fish and Wildlife Service, Washington, D.C. 55 p.

Weiher, E., I. C. Wisheu, P.A. Keddy and D.R.J. Moore. 1996. Establishment, persistence, and management implications of experimental wetland plant communities. Wetlands 16: 208-218.
 

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