An example of natural selection: Galapagos Finches

There are 13 types of Galapagos finches, also known as Darwin's Finches, and they share the same
habits and characteristics except for one: All 13 have different beaks. The differences in their beaks
might be the most important aspect of their survival. Two documented examples of that survival
occurred in the late 1970s and mid 1980s. First, when a large drought affected the island in 1977,
5 seeds became scarce. Finches with the largest, toughest beaks were able to eat larger seeds that
weren't typically part of their diet. As a result, they survived. Finches with smaller beaks were
unable to crack the tough seeds and many died. Through the process of natural selection, the large
beak birds reproduced and thrived, while the other type dwindled in number. However, adaptation
can go both ways, as was seen during rainy weather in 1984 and 1985. The heavy rains created
10 more of the small, soft seeds and few of the large ones. This time, more birds with the smaller beaks
survived and produced more offspring.
By Diana Bocco
http://dsc.discovery.com/tv-shows/curiosity/topics/10-examples-natural-selection.htm
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