ScienceDaily (Mar. 22, 2010) — Evolution can proceed much more rapidly than has long been thought. This is shown by Magnus Karlsson, a doctoral candidate at Linnaeus University in Kalmar, in his dissertation about the impact of genetics and the environment on the color patterns of pygmy grasshoppers.
Pygmy grasshoppers exist in many different color variants and in many types of environment. Through a series of experiments and studies in nature, Magnus Karlsson discovered that the distribution between the color variants of pygmy grasshoppers differs across different environments. In recently burnt over areas, a very high proportion of the grasshoppers are black. In unburnt areas, on the other hand, the black variant is unusual. What's more, the proportion of black grasshoppers changes very rapidly between generations in the burnt areas, whereas the proportion in unburnt areas remains the same over the same period of time.
Magnus Karlsson presents data that show that the pygmy grasshoppers' color changes by natural selection. He believes that the primary cause of these changes is birds and other animals that hunt using their vision. The black grasshoppers are simply less visible against the burnt background, so they survive more often. But as the environment changes and becomes more complex, the advantage of being dark diminishes, and other color variants can once again increase in number.
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Magnus Karlsson's dissertation is titled Evolution in Changing Environments Revealed by Fire Melanism in Pygmy Grasshoppers.
