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Finch Beaks
and
Natural Selection
By: Johnny B. Goode
Warbler Finch
Darwin and Finches
• When Darwin explored the Galapagos Islands,
he noticed many different types of finches on
the different islands
• He came up with the idea that they came from
the same ancestor and became new species
through natural selection.
• Each island had different finches from the
others
Warbler Finch
The Finches of the Galapagos
Woodpecker Finch
Experiments in the Galapagos
• 1973 – Peter and Rosemary
Grant begin studies on
natural selection and
finches in the Galapagos
islands, specifically Daphne
Island
• 1977 – wet season did not
occur, resulting in huge
drought
– More than 1,000 finches died
Medium Ground Finch (G.fortis)
Experiments in the Galapagos
• After drought, there were more big G.fortis
finches than small ones
• Big finches can eat bigger seeds that small
finches can’t
– Being more flexible with type of food allowed the
big finches to survive after the small finches ran
out of food
Medium Ground Finch (G.fortis)
Result of Drought on Finch Beak Size
Small Tree Finch
Genetics and Finch Beak Size
• Before the drought, there was a wide variety
of beak sizes in G.fortis, including big beaks.
• After the drought, there were more bigbeaked finches left, and they reproduced to
create a generation of big-beaked finches.
• The finches with big beaks had genes that
made them have big beaks and then their
offspring had big beaks, too.
Vegetarian Finch
References
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Background photo:
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Background sounds
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http://biology.unm.edu/ccouncil/Biology_112/Images/FinchTypes.jpg
Experiments in the Galapagos
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Zimmer, C. (2006). Evolution: The Triumph of an Idea. New York: Harper Perennial.
Finches of the Galapagos
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Medium Ground Finch: http://www.xeno-canto.org/sounds/uploaded/DABODLPUPA/Medium_GroundFinch_Floreana1_7-28-08.mp3
Small Tree Finch: http://www.xeno-canto.org/sounds/uploaded/DABODLPUPA/Small_Tree-Finch_7-28-08.mp3
Vegetarian Finch: http://www.xenocanto.org/sounds/uploaded/XTVEPHMPPJ/Platyspiza_crassirostris_1979_02_22.mp3
Warbler Finch: http://www.xeno-canto.org/sounds/uploaded/DABODLPUPA/Warbler_Finch1_7-26-08.mp3
Woodpecker finch: http://www.xenocanto.org/sounds/uploaded/XTVEPHMPPJ/Camarhynchus_pallidus_1979_02_22.mp3
Darwin and Finches
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Allen, S. (n.d.). Birds of the Galapagos Islands & South America. Retrieved October 04, 2009, from Steve Allen Travel &
Wildlife Stock Photography: http://www.steveallenphotography.com/64.html
Zimmer, C. (2006). Evolution: The Triumph of an Idea. New York: Harper Perennial.
Image: Explore Evolution. (n.d.). Retrieved October 04, 2009, from University of Nebraska State Museum:
http://explore-evolution.unl.edu/grant.html
Result of Drought on Finch Beak Size
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Morris, T. (n.d.). Ecological Genetics: Adaptation and Natural Selection. Retrieved October 04, 2009, from Ecological
Genetics:Adaptation and Natural Selection: http://staffwww.fullcoll.edu/tmorris/elements_of_ecology/chapter_5.htm