Background

1

• Background
• Charles Darwin
• Born on February 12, 1809, same as Abraham
  Lincoln.
• Sailed around the world on the HMS Beagle.
• Made observations that led to the theory of
  evolution
• Wrote Origin of Species.
• Galapagos islands
• ¾ the size of the Hawaiian Islands.
• Each island has a different climate.
• About 625 miles off west coast of South America.

2

• Evolution process by which modern organisms
  have descended from ancient organisms.
• Natural selection
• Individuals that are better suited to their
  environment survive and reproduce most
  successfully.
• Also called survival of the fittest.
• 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?

3

• Natural selection vs. selective breeding
• Natural selection allows nature to decide which
  traits are past to the offspring.
• Predator-prey relationship determines this.
  (fastest, strongest survive)
• Selective breeding allowing certain individuals
  with desired characteristics to produce the next
  generation.
• Ex farmers want fattest hogs, cows that produce
  the most milk, reddest tomatoes, etc.
• Traits benefit humans, not nature.

4

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

5

• Darwin concluded that homologous structures show
  common ancestry.
• Functions may be different when mature (fin vs.
  wing), but look similar at the embryonic stage of
  development.
• Divergent vs. Convergent Evolution
• Divergent evolution process of 2 or more
  related species becoming more and more different.
• Diverge separate

6

• Figure 16-13 Divergent Evolution

7

• Convergent evolution unrelated species become
  more and more similar in appearance as they adapt
  in the same kind of environment.
• Converge come together
• Figure 17-23 Shark, penguin, dolphin

8

• Fossil record
• Fossil any preserved part or trace of an
  organism that once lived.
• Formed when organism is buried before it decays.
• Found in sedimentary rock (layers of mud, silt,
  and sand on top of it).
• Determining the age of a fossil
• Age is determined by the location in rock.
• Fossils closest to the surface are newer than
  those deeper.

9

• Figure 17-3 page 419

10

• Radioactive dating
• Half-life time required for half of the
  radioactive atoms in a sample to decay.
• Carbon-14
• Half-life is 5,730 years.
• Used for younger fossils.
• Uranium-238
• Half-life is 4.5 billion years.
• Used for older fossils.