Island Biogeography Lab.docx - Name Class Date APES Lab...

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Name:__________________________________________ Class:______ Date:__________________________ APES Lab: Island Biogeography Background: Island biogeography is the study of community diversity on islands. One of the variables studied is the rate of colonization by additional species – called recruitment. The farther an island is from the mainland (or the source of colonists), the less frequently new colonists will arrive and become established. Also, the larger an island, the more likely it is more colonists to “find” that space and establish themselves on the island. Another variable is the carrying capacity of the island. Small islands contain fewer resources and support populations of fewer individuals. Small populations are more susceptible to local extinction; so small islands have fewer species than equivalent large islands. Small islands also have a higher ratio of perimeter to area than larger islands. This is important because at the borders of habitats, the physical conditions are often a combination of the conditions of either habitat. An example on oceanic islands is the perimeter of the forest, which will be buffeted by salt spray, while the forest’s center will not be. This creates an “edge effect.” The principles from island biogeography can easily be applied to terrestrial situations. For example, alpine habitats are usually separated by lowland habitats, and lake habitats are separated by terrestrial and stream habitats. Fragmented habitats, such as rainforest parcels separated by farmlands, can be considered “islands.” Many wildlife managers have taken the effects of “island” size into account and have begun to link smaller fragments of habitat together using small corridors to effectively increase the island size. (Costa Rica is an example.) There has also been increasing concern that if a catastrophe damages a nature preserve that is essentially an island, the preserve may not recover quickly unless there is a source of colonists

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