What metaphors are used in The Song of the Dodo: Island Biogeography in an Age of Extinctions by David Quammen?

Chapter One serves as a brief introduction to Quammen's main subject, the division of the natural environment into isolated pieces that act as virtual islands. As a metaphor, he asks the reader to imagine a large and elaborate Persian rug that has been cut into thirty-six pieces. Each piece is equally complex and well made, but the overall pattern has been ruined and the edges begin to fray.