Download Evolution Power Point - Effingham County Schools

What factors can lead to evolution?
• Several factors can lead to evolution: genetic drift,
gene flow, mutation, sexual selection, and natural
selection.
• Gene flow is the exchange of genes between
populations.
• The more gene flow that exists between populations,
the more similar the populations will be.
• The less gene flow, the more likely the two
populations will be different.
• If there is no gene flow between two population then
a new species can arise.
What are Isolated Populations?
• When gene flow stops, the populations are said to be
isolated.
• Isolated Populations result in populations becoming
more and more genetically different.
• Members of the two populations
will begin to look and behave differently from one
another.
• When members of different
populations can no longer
mate successfully, reproductive
isolation occurs.
Reproductive Isolation
• Reproductive isolation
is the final step of
becoming separate
species (speciation.)
• Speciation is the
evolution of 2 or more
species from one
ancestral species.
Have a Convo 
1) Gene flow…How
does this flow work?
2) What happens
when gene flow
stops?
What causes Reproductive Isolation?
• Behavioral, Geographic,
and Temporal
behaviors
Behavioral
Isolation
Isolation caused by
differences in
courtship or mating
behaviors.
Geographic
Isolation
Isolation caused by
physical barriers
that divide a
population.
Most common
isolation
Temporal
Isolation
Isolation exists
when timing
prevents
reproduction
between populations
Evolution Notes Round Up
• Use your Biology book (p. 344) and answer the
following questions. You DO NOT have to write the
questions BUT answer questions in a COMPLETE
SENTENCE.
1. How can reproductive isolation lead to speciation?
2. What are three types of barriers that can lead to
reproductive isolation?
3. How can lack of gene flow between two populations
lead to speciation?
4. Turn In 
Patterns of Evolution
•
•
•
•
•
Natural Selection
Convergent Evolution
Divergent Evolution
CoEvolution
Extinction
Natural Selection
• Natural Selection:
individuals with
traits that are better
adapted for their
environment have a
better chance of
surviving and
reproducing.
Peppered Moth Journal Article
Peppered Moth Lab Simulation
Convergent Evolution
• Convergent Evolution: evolution towards
similar characteristics in unrelated species
Dolphins, which are mammals,
and sharks, which are fish, have
evolved similar tail fins to adapt to
similar environmental conditions.
Divergent Evolution
• Divergent Evolution: closely related
species evolve in different directions
• For Example; the Kit fox and Red fox
Coevolution
• Coevolution: two or
more species evolve in
response to changes in
each other
• For example: Humming
birds pollinating
flowers
• Flowers pollinated by
insects and other
animal evolve in a
trumpet style. In
response to this, birds
evolved longer, slender
beaks.
Extinction
• Extinction: the elimination of a species
from Earth
• How does extinction occur?
species can not adapt to their
environment
• Two types of extinction are
background extinction and mass
extinction.
Background
Extinction
• Occurs continuously
but at a very slow rate
• Affects one or a few
species at a time
Mass Extinction
• Very intense and very
rare
• Occurs on a global level
• Result of a catastrophic
event such as an ice
age or asteroid impact
Theory of Punctuated
Equilibrium
• Paleontologists have
noticed repeating
patterns of evolutionary
activity followed by
long periods of
stability.
• Punctuated Equilibrium
states that episodes of
speciation occur
suddenly in time and
are followed by long
periods of little
evolutionary change.
Patterns of Evolution
Natural
Natural
Selection
Selection
Definition
Define
How can
you
remember the
How can you
definition
remember?
Illustration
Illustration
Patterns of Evolution Research, Draw,
and Tell Activity
Convergent
Divergent
Evolution Evolution
Coevolution Extinction
Mass
Extinction
Group I:
Research
Group 3:
Research
Group 5:
Research
Group 7:
Research
Group 9:
Research
Group 2:
Illustrate
an example
Group 4:
Illustrate
an example
Group 6:
Illustrate
an example
Group 8:
Illustrate
an example
Group :
Illustrate
an example
Research: Define and explain to class. Use construction
paper to write definition NEATLY in MARKER.
Illustrate: Draw and show/explain to class. Drawing
must be on construction paper as well. Drawing must be
in color and labeled.