The document summarizes key concepts about evolution from biology class. It describes how Charles Darwin developed the theory of evolution through his observations on the Galapagos Islands of different finch species with specialized beaks. Darwin proposed that evolution occurs through overproduction of offspring, competition for resources, genetic variations or adaptations, and survival of the fittest. The theory helped explain how the first single-celled organisms evolved over 3 billion years into the diversity of species today through natural selection, mutation, and genetic drift acting on populations.

1. Chapter 25: Evolution
Biology: Mrs. Neistadt

2. Changes Over Time:
 *Most species change over time. This
slow, gradual change is called
Evolution
____________________.
 Evidence shows the first living creatures
were single-celled organisms living in the
oceans 3 billion years ago.
 *Many species have become extinct.
Extinct species were once living, but no
longer exist.

3. Jean Baptist Lamarck
 In the 1800s scientists were studying and
discovering __Fossils .
 A fossil is the remains of an organism that
lived long ago.
 Jean Baptist Lamarck proposed one of the
first theories of evolution.
 He thought organisms developed traits by
using or not using parts of their body.
 Example: Giraffes
Incorrect!

4. Charles Darwin
 In 1831 an Englishman named Charles Darwin took
a trip on the HMS Beagle.
 He was to map the coast of South America.
 He stopped on the Galapagos Islands where he
began a study that would turn scientific study in a
new direction.
 Darwin discovered the various Galapagos Islands
had different species of animals.
 He noticed 13 species of finches. Each finch had a
different beak, specialized to find food on its
island.

5. Charles Darwin
 Charles Darwin spend 20 years thinking
about his discoveries.
 *In 1859, Darwin wrote the book, “The
Origin of Species” to explain his theories
on evolution.

6. *Four Points to Darwin’s Theory:
*Overproduction
*Competition
*Variations or Adaptations
*Survival of the Fittest

7. Charles Darwin

8. Genetic Variations:
 Darwin did not know HOW genetic traits
were passed on.
 *A gene pool is the combined genetic
information of all members of a
population.
 By studying the gene pool of a
population, scientists can see how
variations in traits are passed to offspring.

9. *Events That Can Cause
Evolution:
*Natural
Selection
*Evolution can
only occur when
*Mutation an event causes
changes in the
gene pool.
*Genetic Drift

10. Natural Selection
 *Natural Selection is the way that
organisms best suited to an environment
survive

11. Mutation
 *Mutation: If a mutation is harmful the
organism may die before passing on the
gene. If the mutation is helpful, the
organisms live and pass the gene on.

12. Genetic Drift
 Genetic Drift is changes within a gene pool
that occurs due to random events, or
when individuals leave or join the
population.

13. 3 Types of Evolution:
Divergent Convergent
Coevolution
Evolution Evolution
Different
Types of
Evolution

14. Your turn…
Create a graphic organizer to
Compare the 3 types of evolution:
Divergent
Convergent
Coevolution
Use Internet research and/or your
textbook Pg398 to help you.