Tuesday, September 12, 2006
The notion of islands as natural test beds of evolution is nearly as old as the theory itself. The restricted scale, isolation, and sharp boundaries of islands create unique selective pressures, often to dramatic effect. Following what's known as the 'island rule,' small animals evolve into outsize versions of their continental counterparts while large animals shrink. Giant tortoises and iguanas still inhabit the Galapagos and a few other remote islands today, but only fossils remain of the dwarf hippopotami, elephants, and deer that once lived on islands in Indonesia, the Mediterranean, and the Pacific Ocean. The fossil record suggests that these size changes occur rapidly after species become isolated on islands, but this long standing assumption has never been empirically examined in a systematic manner. Now, in a new study published in PLoS Biology, Virginie Millien confirms that island species undergo accelerated evolutionary changes over relatively short time frames, between decades and several thousand years.
Based on the open access PLoS Biology paper "Morphological Evolution Is Accelerated among Island Mammals"
Also see "Scientist's persistence sheds light on marine science riddle (The 'Island Rule')" posted Thursday, September 07, 2006
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