Example 1: Krakatau Island

One famous "test" of the theory was provided in 1883 by a catastrophic volcanic explosion that devastated the island of Krakatau, located between the islands of Sumatra and Java. The flora and fauna of its remnant and of two adjacent islands were completely exterminated, yet within 25 years (1908) 13 species of birds had re-colonized what was left of the island. By 1919-1921 28-bird species were present, and by 1932-1934, 29. Between the explosion and 1934, 34 species actually became established, but five of them went extinct. By 1951-1952 33 species were present, and by 1984-1985, 35 species. During this half century (1934-1985), a further 14 species had become established, and 8 had become extinct. As the theory predicted, the rate of increase declined as more and more species colonized the island. In addition, as equilibrium was approached there was some turnover. The number in the cast remained roughly the same while the actors gradually changed.

The theory predicts other things, too. For instance, everything else being equal, distant islands will have lower immigration rates than those close to a mainland, and equilibrium

\IMMIG Curve

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