III. Island Biogeography. III. Island Biogeography. Biogeography : The study of the distribution of organisms in space and time. Biogeography looks at four fundamental processes:.
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Biogeography: The study of the distribution of organisms in space and time.
1. Dispersal: Movement of organism(s) from a point of origin (= location of source, or ancestral, population) to a new location.
2. Colonization: Organism reaches new location, survives, reproduces, and establishes new population.
3. Extinction: Species is eliminated from a particular area (i.e., no more reproducing individuals present); species may survive elsewhere, and may re-colonize area where it went extinct.
4. Evolution: Surviving population in a particular area undergoes change(s) in frequency of gene alleles; may result in altered phenotype, and, given sufficient time, possibly the formation of new species (= speciation).
exploring isolated islands noted new types
of plants and animals, which were often
distinctive for each island or island group.For several centuries, scientific focus was on
cataloging the diversity of island organisms.
Darwin speculated on possible means by which organisms colonized islands and evolved into new species (e.g., Galapagos finches)
Current Sea Level
Submerged Land Bridge
California Channel Islands
Block Island, Nantucket, Martha’s Vineyard
Source: New Scientist, 8 Nov. 2008
Dogger Bank, an upland area of Doggerland, outlined in red.
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1. San Salvador’s offshore cays: Rising sea level caused
erosion of San Salvador, leaving many small, erosion-
Resistant islands, or cays (“keys”).
Current Sea Level
Former Sea Level