1. AIM: How do we describe the theory of
evolution?
Do Now: What does survival of the
fittest, (only the strong survive)
mean to you?
2. Evolution
• Evolution is defined as
change over time.
• Scientists have collected
data to show that
species have changed
over time.
3. Charles Darwin
• He traveled around the world as a naturalist
examining different habitats and species.
• Based on his findings Darwin proposed a
mechanism for evolution, as natural
selection.
4. Natural Selection
• Overproduction- more offspring are produced than
can actually survive (finding nemo)
• Variation- genetic recombination and mutations
• Struggle for survival- offspring compete for
resources and survival, the best adapted will survive.
• Reproduction- the genes that give the organism an
advantage have an adaptive value are passed onto
future generations
5. Acquired Traits
• Only the genes you are born with can be
passed down.
• Only traits in the gametes will be passed to
the offspring.
• Traits you acquire or gain over your lifetime
can not be passed on, memory cells, learning
another language, etc.
6. Evolution by Natural Selection
• Natural selection
– Differential success in
reproduction (unequal
ability of individuals to
survive and reproduce)
– Occurs through an
interaction between the
environment and the
variation among the
individuals in a
population.
7. Conditions for Natural Selection
• Variation
– Individuals must have different
features
• Inherited basis
– Variation must have genetic
basis
• Differential survival &
reproduction
– Struggle for existence leads to
some individuals surviving and
reproducing more successfully
than others
