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EVOLUTION IN ACTION
Pages 308-311
EVOLUTION OF POPULATIONS
•Evolution of a population is due to the environment and the
interaction of the other species in that environment
TYPES OF EVOLUTION
Convergent Evolution:
•Organisms with very different
ancestors become more alike due to
a common environment
•Compare analogous structures: same
functions but different development
WHAT IS SIMILAR?
CONVERGENT EVOLUTION
Analogous Structures example:
Bird wings and insect wings
DIVERGENT EVOLUTION
•Populations become more and more dissimilar
to adapt to the environment
•They share a recent common ancestor
•Compare homologous structures: similar body
part, but may have a different function
Homologous structures
example:
The bones of the human
arm, cat leg, whale
flipper, and bat wing
ADAPTIVE RADIATION
•Adaptive Radiation: population undergoes divergent evolution
until it fills all areas of the environment
•Ex. Darwin’s finches
COEVOLUTION
•When two species each evolve in
response to each other over a long
period of time
•This leads to a close relationship
EXAMPLES
•Rough-skinned newt and garter snake
•Newt evolved to produce neurotoxins then the
snake evolved resistance to this toxin through
genetic mutations
•Hummingbirds and bird pollinated flowers
•Humming birds have long, narrow beaks, and the
flowers are also long and narrow preventing most
insects from getting in
ARTIFICIAL SELECTION
•Humans breed for specific traits causing differences in species
•Ex. Dog breeding
Remember, humans (not the environment) do the selecting of favorable traits