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I. BackgroundA. Charles Darwin

1. Born on February 12, 1809, same as Abraham Lincoln.

2. Sailed around the world on the HMS Beagle.

3. Made observations that led to the theory of evolution

4. Wrote Origin of Species. B. Galapagos islands

1. ¾ the size of the Hawaiian Islands.2. Each island has a different climate.3. About 625 miles off west coast of

South America.

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II. Evolution – process by which modern organisms have descended from ancient organisms.

A. Natural selection:1. Individuals that are better suited to

their environment survive and reproduce most successfully.

2. Also called survival of the fittest.3. Ex: Arctic hares hair color

white (dom) vs. brown (rec)• Which allele will show up the most?• Which organism has a higher chance of

survival in the arctic?

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B. Natural selection vs. selective breeding1.Natural selection allows nature to

decide which traits are past to the offspring.a)Predator-prey relationship determines

this. (fastest, strongest survive)2.Selective breeding – allowing certain

individuals with desired characteristics to produce the next generation.a)Ex: farmers want fattest hogs, cows

that produce the most milk, reddest tomatoes, etc.

b)Traits benefit humans, not nature.

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C. Homologous structures – structures that have different mature forms but develop from the same embryonic tissues.1.Figure 15-15, page 384.

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2.Darwin concluded that homologous structures show common ancestry.

3.Functions may be different when mature (fin vs. wing), but look similar at the embryonic stage of development.

D. Divergent vs. Convergent Evolution1.Divergent evolution – process of 2 or

more related species becoming more and more different.a)Diverge = separate

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b)Figure 16-13 Divergent Evolution

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2.Convergent evolution – unrelated species become more and more similar in appearance as they adapt in the same kind of environment.a)Converge = come togetherb)Figure 17-23 Shark, penguin, dolphin

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III.Fossil recordA. Fossil – any preserved part or trace of

an organism that once lived.1. Formed when organism is buried before

it decays.2. Found in sedimentary rock (layers of

mud, silt, and sand on top of it).B. Determining the age of a fossil

1. Age is determined by the location in rock.a) Fossils closest to the surface are

“newer” than those deeper.

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b)Figure 17-3 page 419

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2.Radioactive dating:a)Half-life – time required for half of

the radioactive atoms in a sample to decay.

b)Carbon-14:1)Half-life is 5,730 years.2)Used for younger fossils.

c)Uranium-238:1)Half-life is 4.5 billion years.2)Used for older fossils.