ABSTRACT

In the opening paragraph of the Origin of Species, Charles Darwin refers to the role of his voyage on the Beagle in inspiring his ideas. This conjures up an image of the young Darwin hard at work on the Galápagos, frenetically hunting up specimens on the islands' parched lava fields, the Beagle picturesquely anchored all the while off-shore. In evolutionary biology, an island can be defined simply as a patch of suitable habitat surrounded by an inhospitable matrix that cannot readily or easily be crossed. There are several broad attributes of islands that dictate their biological properties: isolation, age, size, initial state, and scale dependence. The most striking evolutionary phenomenon associated with remote de novo island is adaptive radiation, a burst in evolutionary diversification yielding a range of species derived from a single common ancestor and showing distinct but related adaptations. Three ingredients are critical to the process: ecological opportunity, isolation, and a new environment.