Darwin’s Map Activity• Map the coordinate that Darwin traveled on his Voyage of the

Beagle. Add the numbers to show the sequence.• Connect the dots from the start to the end of his trip (it should

start and end in England).• Answer the 18 questions on the back of the map.• Draw small pictures to represent the observations Darwin

made as he explored places along his route. If you don't have room on your map, you may want to draw the illustrations on an additional sheet of paper and number them to correspond to places on the map.

• List 5 significant observations Darwin made in one column and the significance of the observations in another column. Reflect on the importance of Darwin's voyage to the development of his theory of natural selection.

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Darwin’s Finches Notes (pg 64 in notes)

by Cheryl Heinz, Dept. of Biological Sciences, Benedictine

University, and Eric Ribbens, Dept. of Biological Sciences, Western Illinois University

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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.– 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.

• 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.

• Another way of saying this is that there is very little gene flow between the islands and the mainland.– Gene flow = animals of the same species but a different

gene pool are introduced into a population

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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.

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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.

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Charles Darwin’s Ideas

• Biological evolution is change 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

• 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.– 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.

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EndemicsAmong 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

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The Finches• The 13 finch species include:

– 6 species of ground finches– 3 species of tree finches– 1 woodpecker finch– 1 vegetarian finch– 1 mangrove finch– 1 Coco Island finch

• A warbler finch that looks more like a warbler than a finch (one of the tree finches).

• The woodpecker finch actually uses cactus spines to dig grubs out of branches!

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Evolution is:A change in the frequency of an allele, such as an allele for beak depth, is the basic definition of evolution.

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Evolution by Natural Selection

Steps:

1. Individuals vary in some traits.

2. Some of the differences in traits are passed along to offspring.

– This requires a genetic basis to the trait– The trait is thus heritable

(more…)

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Evolution by Natural Selection

3. Different individuals produce different numbers of surviving offspring.– Produce different numbers, or– Different numbers survive.

4. The particular value of a trait is connected to the number of offspring produced.– Traits that allow for more offspring to be

produced are said to be “naturally selected.”

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Types of evolution

• Microevolution – changes in the gene (allele) frequencies in a population over a short period of time

• Macroevolution – changes in the gene (allele) frequencies in a population over a large amount of time that essentially differentiates a population from the rest of the species.

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Evolution

• Changes in the population are due to 4 main mechanisms:– Mutation– Natural selection– Gene flow– Genetic drift

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