ISLAND BIOGEOGRAPHY

  1. Definitions
  2. Island Biogeography Theory
  3. Examples of Island Biogeography
  4. Habitat Islands
  5. Endemism

DEFINITIONS

biogeography: the study of the geographic location of species.

island biogeography: the study of the species composition and SR on islands

equilibrium species number: The SR of an island at which immigration balances extinction, and which remains roughly constant.

extinction and immigration: These mean slightly different things in community ecology. Extinction is the disappearance of a species in a community. Immigration is the appearance of a species in a community ("speciation" is almost nonexistent in the spatial and temporal scales used by ecologists)

Island biogeography theory (IBT): a theory proposed to account for the equilibrium SR on islands.

FIGURE ILLUSTRATING ISLAND BIOGEOGRAPHY

EXAMPLES OF ISLAND BIOGEOGRAPHY

Simberloff and Wilson 1970:

Small mangrove islands in the Florida Keys exhibit high arthropod SR on large and near islands, and low SR on small and far islands predicted according to IBT. They then fogged the islands with methyl bromide, and followed arthropod populations. Within several weeks, SR returned approximately to previous levels, implying they had reached equilibrium.

Diamond 1969:

Diamond compared 1917 and 1968 bird surveys of the Channel Islands of California, which vary in size and distance from the mainland. There is approximately the same SR in both surveys. However, species composition was different (30% of the species were not shared between the two surveys). This implies that the islands have equilibrium SR, though not species composition.

HABITAT ISLANDS

Habitat islands: areas which are not islands, but can be considered as such for IBT

Endemism

Because of reproductive isolation, old islands tend to have a large degree of endemism: species are confined to only one location.

This page was created and is maintained by Mike Palmer.
carex@okstate.edu
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