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Unformatted text preview: 1 Biogeography – Readings Levinton, Chapter 3, pp. 61-68; Chapter 17, pp. 492-515. Supplemental Readings 1) MacPherson, E. 2002. Large-scale species richness gradients in the Atlantic Ocean. Proceeding of the Royal Society, London B 269:1715-1720. 2) Bowen, B. W. & Grant. 1997. Phylogeography of the sardines ( Sardinops spp.): assessing biogeographic models and population histories in temperate upwelling zones. Evolution 51:1601-1610. Biogeography = Study of the historical and present-day factors determining the distribution and abundance of organisms over the earth Two types of questions Pattern : Where do organisms occur and what is their abundance? Process: How did they get where they are? (History) What factors limit their distribution and abundance? (Ecology) The start of global oceanography and marine biogeography H.M.S. Challenger voyage (1872-1876) gave the first global picture of the oceans and some of it organisms Scientific cruise under the direction of Wyville Thomson, Professor of Natural History at Edinburgh University. H.M.S. Challenger traversed 68,890 nautical miles, including the North and South Atlantic and Pacific Oceans and traveled north of the limits of drift ice in the North Atlantic polar seas and south of the Antarctic Circle. At the time, there was little knowledge of the world oceans and it was debated whether or not there was ANY life in the deep sea. At each station, the fol owing observations were made aboard the Chal enger Physical Oceanographic Observations- exact depth was determined with a sounding line- a bottom sample was taken- a sample of bottom water was taken for chemical/physical examination- bottom temperature was recorded by a registering thermometer- at most stations, a series of temperature observations was made at different depths from the surface to the bottom- at many stations, samples of sea-water were obtained from different depths- atmospheric and other meteorological conditions were observed and noted- direction and rate of the surface current was determined Biological Oceanography- often a sample of the bottom fauna was procured by means of the dredge or trawl.- at most stations, fauna of the surface and of intermediate depths was sampled with nets The Report of the Scientific Results of the Exploring Voyage of H.M.S. Chal enger during the years 1873- 1876 occupied 50 volumes The findings of the cruise were described by John Murray in 1895 as "the greatest advance in the knowledge of our planet since the celebrated discoveries of the fifteenth and sixteenth centuries" Marine Biogeography is similar to terrestrial biogeography but with some important differences Dispersal is often easier for marine organisms compared to most freshwater and terrestrial organisms (although many terrestrial groups – birds and plant – are also highly dispersive) Larval stage : long-lived ones often able to disperse over habitat gaps 2 A) Short-term ecological processes affecting regional biodiversity 1) Species interactions with the physical environment...
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- Fall '09