Evolution= genetic change of a population
over time
More specifically….
• Evolution is the change in allele frequencies
over time
• Review: What is an allele?
Does evolution affect individuals?
• Does the sequence of your DNA change
throughout your life?
• Is it possible for evolution to change an
individual…..?
• ……No! Evolution does not act on the
individual!
• Evolution happens in a population
• Evolution does not happen in an individual
In 1859, Darwin published his
magnificent work, The Origin of
Species.
Two main points of the text were:
1. Descent with Modification Darwin proposed that species
were, in fact, not created in their
present forms, but rather had
common ancestry with other
extant species.
2. Darwin proposed natural
selection as the mechanism for
this descent with modification.
Darwin began to notice that organisms in isolated locations
(i.e., on islands) often bore resemblance to their mainland
counterparts, but with slight morphological changes.
He began to wonder about the long-held assumption that
species were created in their present forms.
Darwin’s Four
Postulates:
1. In every
population there
is variety.
(some that is inherited,
some that is not)
2. Some of that variety is passed on to
offspring.
He’s got your
eyes!
3. There are more
individuals born than can
survive
Some offspring will die because of
disease, predators, and resource
availability.
4. The individuals that have
the most advantageous of
traits for a given
environment will better
survive to reproduce
(therefore passing their
genes on to offspring). Over
time, this will change the
genetic frequencies in a
population (EVOLUTION!)
(Survival of the Fittest)
Not THIS kind of fit...