Download 1. Ch. 14 PPT Notes part 1

Evolution: How Change
Occurs
Chapter 14
14.1 Developing a Theory of
Evolution
• evolutionary theory is fundamental to the
study of Biology
• Genetics, ecology, and medicine are all
based upon the evolutionary theory
• Fact or Theory?
– Fact: fossils give evidence that organisms
have changed over time
– Theory: how the changes have occurred.
Lamarck – Acquired
Characteristics Theory
• Noticed that
organisms changed
over time long before
Darwin made his
voyage on the HMS
Beagle
• Relied on three
assumptions that we
now know are
incorrect
1. Desire to Change
All organisms were born with the desire to make
themselves better adapted to their environment.
Ex. Birds wanted to fly, so over many generations
they acquired wings
2. Use and Disuse
Using or not using a
particular body structure
leads to strengthening or
disappearance of the
structure
(does this happen?)
3. Inheritance of Acquired Traits
Believed that features
acquired during an
organism’s lifetime
could be passed on to
their offspring
(What’s wrong with this
idea?)
Lyell – Earth’s History
Studied geology and
determined that the Earth
was very old and has
changed over time
Important because the Earth
has to be very old in order
to account for the millions
of years needed for a
species to evolve from a
common ancestor.
Farming - Artificial Selection
What farmers knew:
-plants and animals vary
greatly in their
characteristics
- Offspring share many
characteristics of their
parents
-favourable variations
could be enhanced
through selective
breeding
Malthus- population studies
- Species produce more
offspring than the
environment can support
- Only a small number will
survive and reproduce.
14.2 – Evolution by Natural
Selection
Darwin’s Conclusion:
• Wild plants and animals have inherited
variations
• Struggle for existence – only the “fit” survive
• Individuals whose characteristics are well-suited
to the environment survive. Individuals whose
characteristics are not well-suited to their
environment either die or leave fewer offspring.
(Survival of the Fittest)
Peppered moths – Natural
selection in action
Different colours are more successful in different
environments…
Another example – antibiotic
resistance in bacteria
• Some bacteria have
natural resistance to
antibiotics
• Using the antibiotic
kills the ones that
don't have this
variation, the resistant
ones survive and
reproduce….
Make sure you can summarize:
1)Darwin’s process of Natural
Selection (vs. Lamarck’s theory)
2) Survival of the fittest
3) the case of Peppered Moths