Download Notes 8.6 – Types of Evolution

Science Starter #9 – 2/14/17

What are the four steps of natural selection?
Does natural selection act on genotypes or
phenotypes?
TAKE OUT YOUR STEPS OF NATURAL
SELECTION (Stamp)
Sheet of paper for Notes: Types of Evolution
Chapter 15-3
pp. 308-311
Evolution is…

Change of heritable traits of a
population over time
Evolution of a population is due to
environment AND the interaction of
other species
Artificial Selection

Humans breed for specific traits causing differences in
species (i.e. dog breeding)
Natural selection: nature is
“selecting” which traits will
survive in the population

Examples of Evolution

Convergent evolution:
Organisms with different
ancestors become more alike
due to common environment
 Ex. fish and whales- compare
analogous structures:
 Same function but different
development

Examples of Evolution (cont.)

 Divergent evolution: populations become more and
more dissimilar to adapt to the environment
 Compare homologous structures to see shared ancestry
 Ex: Appearance of birds with different sized beaks that are
specific for size of bird seed

Homologous structure: similar body
part but may have different functions
Adaptive radiation

 Population undergoes divergent
evolution until it fills all areas of
the environment

Examples of Evolution (cont.)

Co-evolution: two species evolve in response
to each other over a long period of time
Ex: parasites and hosts, plants and
pollinators

EX: Rough-skinned newt and garter snake
Newt evolved to produce neurotoxins then the
snake evolved resistance to this toxin through
genetic mutations.
Birds and
flowers,
Humans and
bacteria are
other examples