The theory of island biogeography proposes that the number of species found on an undisturbed island is determined by: immigration, emigration and extinction. And further, that the isolated populations may follow different evolutionary routes, as shown by Darwin’s observation of finches in the Galapagos Islands. Immigration and emigration are affected by the distance of an island from a source of colonists. Usually this source is the mainland, but it can also be other islands. Islands that are more isolated are less likely to receive immigrants than islands that are less isolated.
The rate of extinction once a species manages to colonize an island is affected by island size. Larger islands contain larger habitat areas and opportunities for more different varieties of habitat. Larger habitat size reduces the probability of extinction due to chance events. Habitat heterogeneity increases the number of species that will be successful after immigration.
Over time, the countervailing forces of extinction and immigration result in an equilibrium level of species richness.*
Several ideas come to mind after reading this theory:
+ As Rabbit Island is a relatively small island it would be easy to create species extinction via the handywork of even a few men.
+ Cataloguing species that do exist on Rabbit Island will be an exciting project.
+ Capitalism historically has created islands of ever decreasing size via subdivision. See this related post.
+ Manhattan is difficult to comprehend in the context of the above theory.
+ This island should be created!
+ E.O. Wilson, the author of the book above and prime mover of contemporary biological thought, also believed that "the window on wilderness is closing fast in this country. What we secure now will be in a sense a final bequest to all future generations.“ This idea must be reconsidered. Although a retrospective glance supports his idea and it is certainly easiest to preserve land that has not been previously developed, the notion that land can be reclaimed from development for the creation of natural ecosystems larger than currently exist must be considered. As our ability to collect and visualize data rooted deeper in the past and extrapolated further into the future improves, we have no choice but to challenge this sentiment and revise our historical use of incomplete balance sheet equations in matters of land use to more accurately approximate cost/benefit. Consider this when reading the quote in the next post. He was quite right.
+ The Keweenaw Peninsula is an island.