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Charles Darwin
• Darwin explored these islands from April through October 1835.
– Entire voyage of The Beagle: Dec 1831 - Oct 1836
• When and where he started thinking about what was to become his theory of evolution by natural selection. • He did not publish his thoughts until the publication of The Origin of Species in 1859.
• Natural selection is just such a mechanism, and this is what Darwin contributed.
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Galapagos Endemics
• The Galapagos today is an amazing place. • Animals live there that are found nowhere else on earth.
• Another way of saying this is that there is very little gene flow between the islands and the mainland.
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CQ1: Limited gene flow means:
A: Birds rarely move between the mainland and the islands. B: Birds on the island have the same genes as birds on the mainland. C: Birds on the mainland don’t like birds from the islands. D: Birds on the mainland won’t evolve, but birds on the islands might.
• Neighboring islands will have close relatives
– but new terrestrial species won’t arrive on these islands from the South American mainland very often. – most of the island species have had plenty of time to differentiate from their nearest living relatives.
Darwin’s Finches and Natural Selection
by
Cheryl Heinz, Dept. of Biological Sciences, Benedictine University, and Eric Ribbens, Dept. of Biological Sciences, Western Illinois University
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CQ2: Endemic means:
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Charles Darwin’s Ideas
• Biological evolution is in species over time.
– This was not a new idea at the time – But there were no good mechanisms to explain how these changes occurred
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Endemics
Among the kinds of animals found here and nowhere else: – 1 penguin species – 1 giant tortoise species – 1 marine iguana species – 7 species of lava lizard – 14 species of sea cucumber – 1 species of sea lion – 1 species of hawk – several species each of mockingbirds, doves, owls, flycatchers, and yellow warblers
– Mostly ground between the two U.S. cities. – Mostly deep water between the Galapagos Islands and the coast of South America.
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Implications
• Terrestrial species on these islands won’t have many relatives nearby.
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The Galapagos Islands
• Located approximately 1000km from the coast of Ecuador, South America.
• This is just a little closer than the distance between Chicago and Philadelphia.
– This makes them endemic – Perhaps the most famous of the endemic birds are the finches, of which there are 13 different species
• The islands are a natural laboratory, and one in which evolution can be observed.