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Evolution
A process of change through time
Existing forms have evolved from
earlier forms
Diversity leads to evolution
Evidence
• Geologic Record- indicates later life forms
are more complex
• Fossils are preserved in sedimentary rock
• Upper rock layers contain more complex
life
• SIMILIARITY between organisms
suggests common ancestry (anatomy,
cytology,embryology, biochemistry)
• Homologous structures- same number and
arrangement of bones in different species
• Cell organelles are similar in different
organisms
• Embryonic stages are similar in certain
species
• Similar biochemistry- proteins, amino
acids and enzymes in different species
Darwin
• Natural selection- evolution is controlled
by the natural environment
• Traits that enable survival will be inherited
and passed on to the population.
• Conditions for Evolution
• Overproduction- a species will produce
more individuals than necessary
• Competition- only strongest will survive
and pass on favorable traits (Survival of
fittest)
• New traits arise as a result of VARIATION
or MUTATION
• Selection by Environment- organisms with
a high adaptive value will survive and
reproduce. Those individuals will increase
in number, causing a change in
characteristics, and then evolutionary
change