2. Evolution
• The processes that have transformed life on
earth from it’s earliest forms to the vast
diversity that characterizes it today.
• A change in the genes!!!!!!!!
3. Old Theories of Evolution
• Jean Baptiste Lamarck (early 1800’s) proposed:
“The inheritance of acquired characteristics”
• He proposed that by using or not using its body
parts, an individual tends to develop certain
characteristics, which it passes on to its
characteristics
offspring.
offspring
4. “The Inheritance of Acquired
Characteristics”
• Example:
A giraffe acquired its long neck because its
ancestor stretched higher and higher into the
trees to reach leaves, and that the animal’s
increasingly lengthened neck was passed on
to its offspring.
5. Charles Darwin
• Influenced by Charles Lyell who published
“Principles of Geology”.
• This publication led Darwin to realize that
natural forces gradually change Earth’s
surface and that the forces of the past are still
operating in modern times.
6. Charles Darwin
• Darwin set sail on the H.M.S. Beagle (1831-1836)
to survey the south seas (mainly South America
and the Galapagos Islands) to collect plants and
animals.
• On the Galapagos Islands, Darwin observed
species that lived no where else in the world.
• These observations led Darwin to write a book.
7. Charles Darwin
• Wrote in 1859:
1859 “On the Origin of Species
by Means of Natural Selection”
• Two main points:
1. Species were not created in their present
form, but evolved from ancestral species.
2. Proposed a mechanism for evolution:
NATURAL SELECTION
8. Natural Selection
• Individuals with favorable traits are more
likely to leave more offspring better suited for
their environment.
environment
• Also known as “Differential Reproduction”
• Example:
English peppered moth (Biston betularia)
- light and dark phases
9. Darwin’s 5 points
• Population has variations.
• Some variations are favorable.
• More offspring are produced than
survive
• Those that survive have favorable
traits.
• A population will change over time.
10. Artificial Selection
• The selective breeding of domesticated
plants and animals by man.
• Question:
What’s the ancestor of the domesticated
dog?
• Answer: WOLF
11. Evidence of Evolution
1. Biogeography:
Geographical distribution of species.
2. Fossil Record:
Fossils and the order in which they appear
in layers of sedimentary rock (strongest
evidence).
13. Evidence of Evolution
4. Comparative embryology:
Study of structures that appear during
embryonic development.
5. Molecular biology:
DNA and proteins (amino acids)
14. Species
• A group of populations whose individuals
have the potential to interbreed and produce
viable offspring.
