15 February 2011


ISLAND LABS. One of my favorite courses during the pursuit of my degree in Ecology & Evolutionary Biology was Island Biogeography -- a discipline which "attempts to establish and explain the factors that affect the species richness of natural communities," in particular those communities which are isolated by their surroundings -- actual islands in the ocean, or mountain ranges surrounded by desert, or even natural habitats surrounded by human landscapes. Their isolation makes island habitats ideal as laboritories for the study of speciation (the emergence of new species) and extinction (the obliteration of existing species).

If we think of an island as an area of suitable habitat surrounded by an expanse of unsuitable habitat, Island Biogeography proposes that "the number of species found on an undisturbed island is determined by immigration, emigration, and extinction. Further, the isolated populations may follow different evolutionary routes, as shown by Darwin's observation of finches in the Galapagos Islands (in the Pacific Ocean, 525 miles west of Ecuador). Immigration and emigration are affected by the distance from a source of colonists (distance effect). Islands that are more isolated are less likely to receive immigrants. The rate of extinction once a species manages to colonize an island is affected by island size (area effect). 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." (See graph below.)

I recently discovered a new manifestation of islands as laboratories -- for the study of the effects of climate change. The NYTimes article begins, "The sign welcoming visitors to a coral reef island 1000 miles southwest of Hawaii reads, 'Palmyra Atoll, Elevation: 6 feet, Population: 10.'" The article goes on to describe the activities of The Nature Conservancy and the U.S. Fish and Wildlife Service in an ongoing conservation, restoration and research project which has implications for ALL low-lying island and coastal regions, in the event that global warming produces a significant rise in sea level. Island biogeographers may find themselves with fewer, and smaller, islands to study a century from now.

PARADIGM SHIFT. The phrase is almost a cliche, but Julia Galef's article That's Funny -- Incongruity in Humor, Art and Science deftly introduces paraprosdokia, "a figure of speech whose latter half surprises us, forcing us to go back and reconsider the assumptions we'd made about what was going on in the first half." We may experience this mental shift without noticing it -- in listening to a joke, in hearing an unexpected shift in a piece of classical music, and in forming, testing, rejecting or altering hypotheses to explain anything from where we misplaced the car keys to what might explain an observed phenomenon (just as Robert MacArthur and E.O. Wilson did in formulating the foundation of Island Biogeography in the 1960s). The article is entertaining and, well, paraproskokian -- a click of recognition.

FEAR OF HEIGHTS. If you suffer from acrophobia, you might want to reconsider that planned hike on the El Chorro Walkway, a vertiginous manmade path that clings to the sides of a limestone gorge in Spain's Andalucia. The trail is not for the faint of heart. There are few protective railings, the dropoff is sheer, and in places one must balance on metal beams or cling to handholds in the cliff. The six and a half minute video The Scariest Path In the World? (thanks, Irene) is an eye-popping adrenaline rush.

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