Review Mechanism of evolution

Random genetic
changes that occur in
an organism’s DNA

The alteration of allelic
(gene) frequencies by
chance events such as a
natural disaster or the
establishment of a new
population.

Mates are chosen based
on desired trait,
increasing the probability
that a specific allele will
be passed on to the next
generation.

The transfer of genes
from one population to
another population
through immigration or
emigration of individuals

In a garden there were 3 colors
of butterflies: yellow, white, and
blue. The yellow and white
butterflies were able to blend in
with the flowers of the garden,
but the blue ones stood out and
were eaten by predators.

Female peacocks are very
attracted to tail feathers that
are large and colorful. Because
the most colorful males are
getting all of the mates, the
following generation will have
more colorful peacocks.

In Ireland many people have red
hair. One year, there was a large
migration of individuals who
moved from Ireland to the United
States. After some time, the
frequency of red-haired people in
the U.S. increased

A population of beetles consisted
of individual that were brown,
green, orange, red, and blue. A
storm swept through their
environment and randomly killed
off most of the green, orange, and
red beetles. The following
generation was mostly brown and
blue.

Among a generation of
tan-colored mice, one mouse had
a genetic variation causing them
to have black fur. This mouse was
well suited for its dark
environment, so it survived and
reproduced. The next generation
had more mice with black fur.