Download Mechanism of Natural Selection

How does natural selection change
a population?
P. 247-248 What are the five important principles of
natural selection?
P. 250
 What are two sources of variation?
 What is a niche?
P. 258 - 259
 What is a species ?
 What does it mean to be reproductively isolated?
 What is divergent evolution?
 What is adaptive radiation?
 What is convergent evolution?
P. 252 -253 What are stabilizing, directional, and
disruptive selections (include drawings)


Changes that occur within a population of a
single species.
It includes the process of natural selection,
changes in allele frequencies, and changes in
populations that result over time. Development
of antibiotic resistant bacteria is an example of
microevolution.
Video: Why does evolution matter now?


Macroevolution refers to large scale and longterm evolutionary patterns among many
species.
The evolution of new species from a common
ancestor, as seen in Darwin’s finches, or the
extinction of the dinosaurs are all examples.
Stabilizing selection – favours individuals with an
“average” value for a trait, and selects against
those with extreme values. Human birth
weight is an example.
Until recent medical advance, infants that were
too small tended not to survive and infants that
were too large died during birth.
Directional selection – favours individuals
possessing values for a trait at one extreme of
the distribution, and selects against the average
and other extreme.
The development of antibiotic resistant bacteria is
an example of directional selection. Only those
bacteria that can tolerate the presence of an
antibiotic survive.
Video: Evolution of the peppered moth
Industrial Melanism
Disruptive selection – favours individuals at both
ends of the distribution and selects against the
average.
Marine organisms known as
limpets have shell colours
that range from white to
dark brown.
The dark coloured limpets
attached to dark coloured
rocks in the ocean and light
coloured limpets attached
to light coloured rocks tend
to be less visible to
predators and have a higher
survival rate. The
intermediate coloured
limpets (tan coloured) are
highly visible to predators
and are consumed.
The intermediate colour is
therefore being selected
against.
http://www.biologycorner.com/worksheets/pe
pperedmoth.html
Class Height Chart
Directional? Stabilizing? Disruptive?