Finches of Daphne Major
A drought on the Galápagos island of Daphne Major in 1977 reduced the number of small seeds available to finches, causing many of the small-beaked finches to die. This caused an increase in the finches' average beak size between 1976 and 1978.
Source
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"OpenStax College, Discovering How Populations Change. December 6, 2013."
http://cnx.org/content/m45487/latest/
OpenStax CNX
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