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Evolution
With your partner….
 Come up with 1 thing you are absolutely, 100% sure
about the theory of evolution.
 Come up with 1 thing you THINK is true about
evolution.
 Come up with 1 thing that evolution does NOT say.
 Class Discussion.
What evolution does NOT say:
 Does NOT say humans came from apes.
 Does NOT say how life began on Earth.
 Does NOT say one cannot have “faith”
What evolution IS:
 Best theory we have right now to explain the variety
of life on Earth.
 Is supported by an enormous amount of evidence
(that you must know for the test).
 Is open to being changed or discredited if more
scientific data is discovered.
 Is a controversial topic, even today.
Evolution
A change in species over
time.
"Stated Clearly" 8 minute
overview
SPECIATION
 Species-Two organisms that can mate and create
offspring that can also reproduce.
 Speciation videoMr. Anderson….
 4 minute lizard example
 Speciation and Extinction 1 to 2, 1 to 0
Charles Darwin
“Descent with Modification”
Charles Darwin: 1809-1882
 Wrote the book On the Origin of
Species which gave us the theory of
evolution through Natural
Selection.
The THEORY of evolution
 “Well it’s just a theory.”
Wrong. It’s a “Scientific Theory”
 3 minutes on what a Scientific Theory is...
“TIMEOUT! There’s no way all this variety
can happen through evolution,” you say?
 2:44 representation of how it DOES happen like
that! Good for closure
End of Day 1 song:
Evolution Song
NATURAL SELECTION
“THE SINGLE MOST
IMPORTANT FACTOR IN
THE THEORY OF
EVOLUTION”
How Evolution works through Natural Selection
 Natural Selection is the “vehicle” that “drives”
Evolution.
 9 minute example of natural selection mice!
 With your partner, come up with an
analogy to show how evolution and
natural selection are related:
Natural Selection
 A changing
environment makes
adaptations more
likely to become
established . Those
organisms best fit
to the new
environment are
“naturally selected”
for.
The Four Parts of Natural Selection
 Adaptation – The traits that improve survival and
reproduction, become more common than traits that do
not.
 Overproduction – Each population is capable of
producing more offspring than can survive. This create
competition.
 Variation (due to genetic mutations and just random
crosses) – All offspring are different. This makes it more
likely that at least some will fit their environment
 Selection – The offspring best suited to the environment
survive and pass those traits on to their offspring. They
are “selected, naturally, to live and breed.
Adaptation

Overproduction

Variation
Selection
A question to ponder….
 With your partner, discuss how a
giraffe’s neck got to be so long. Be
able to explain the “how” part in
some detail.
Who thought this???
Compare the two theories here

So how DID their necks get so long….
Class discussion….share
your thoughts.
the answer....
THE FOUR PARTS OF…
NATURAL
SELECTION
#1)Adaptations
 Definition: A trait
that makes an
organism better
suited to its
environment
 Adaptations take
time and occur over
many generations
Quick Formative Assessment…
 How did the clam in the video develop the fish-look
alike adaptation?

Note: Show first 2:16 of video and stop it before the question.
Answer follows 2:16.
 Natural Fish Lure | Lampsilis Mussel and Bass
Other Adaptations
 Discuss with your
partner what adaptations
you see in this picture.
On your own, think about what adaptations
are here?
 Clown fish and sea anemone.
What about adaptations here?
 Penguin
Adaptation Independent Practice
 You have 8 minutes to do the first side of the
handout (22-2, Bird Feet Matching Worksheet)
 If you get done early, try the back side (22-3). Try to
figure out what the birds beak and feet are best
suited to do---in other words, what “advantage” do
they give the bird over birds that don’t have that
trait.
Natural Selection: 2)Overproduction
 Organisms produce more offspring than can
possibly survive.
 This creates competition where the best fit for
their environment will survive.
 The competition is due to the fact that
environmental resources are limited.
 With your partner, come up w/3 examples of
competition in nature..
(#2 cont...)Overproduction/Competition Video
 Quick and simple example (16 secs)
 Quick Lecture on Competition
Natural Selection: 3) Variation
 The idea that all members of a species
are slightly different from one another
and this difference is in their genes.
 This variation makes it more likely that
at least some will survive a sudden
catastrophic change or even a series of
small changes. Over time this can lead
to change in species…aka...evolution.
 Sexual Reproduction adds to variation
Genetic Variation…continued
Mechanisms of Variety (2:51)
Part 2
(9:36)
 Result of variety2:32
.
Natural Selection: 4) Selection
 “Survival of Fittest”
 Those organisms best fit to their environment
will survive (be “naturally selected”) and pass
those traits to their offspring.
 The traits are passed on via reproduction.
 Those not fit don’t reproduce and their traits
and genes for those traits aren’t passed.
 9 min Bozeman examples of NS
RE-CAP OF WHAT WE’VE LEARNED SO FAR
 Evolution is the change in a species over time.
 The main driving force of evolution is NATURAL
SELECTION
 Natural Selection is comprised of 4 parts:




1) Adaptations
2) Overproduction (which leads to competition)
3) Variations
4) Selection
Preview of Next Area of Evolution
 Get a piece of paper and answer the following
questions:
 Page 385: 1, 2, 3, 4, 5
 Page 389: 1, 2, 3
 YOU MUST WRITE OUT THE QUESTION AND
THE ANSWER!
Evidence for Evolution
 1) The Fossil Record
 2) Embryology
 3) Comparative Anatomy
 4) Molecular and Biochemistry
With your partner, discuss what
you think each of these may be.
EVIDENCE SUPPORTING EVOLUTION
Evidence for evolution 13
min
Evolution Video Series
These are not meant to be shown all at this time.
 Part 1: Overview of Evolution, begin fossil
 Part 2: Continuation of fossil record
 Part 3: Geologic time and Speciation
 Part 4: Rate…/Embryology/Nucleotides 9;00
 Part 5: Using Genetic differences to show
relatedness (7:25)
 Part 6: Psuedo genes/Retrovirus lineage
1) THE FOSSIL RECORD
 Fossils are the remains of organisms or the imprint
of organisms in rock.
 Fossils are usually found in sedimentary rocks.
 Fossils can be dated by the rocks they are found in or
by Carbon Dating parts of the organism.
The Fossil Record (continued)
Video clip
How Old Is That Fossil?
 One of the challenges in the pursuit of evidence for
evolution was determining the age of the fossils.
 There are a few ways to get an age. Some are much
more accurate than others. Some can give an near
exact date and some can only show “relative” age.
Law of Superposition (Laundry Law)
 Law of Superposition Video (show first 3 mins)
 With your partner, explain how you could
determine how long clothes have been in a
laundry hamper as related to other clothes
in there. Be ready to report out to the class.
Law of Superposition
 Layers of rocks on top are younger than
layers below them.
 IN OTHER WORDS….
 The deeper you go, the older the layer.
Law of Superposition (Laundry Law)
 Law of Superposition Video (show first 3 mins)
 With your partner, explain how you could
determine how long clothes have been in a
laundry hamper as related to other clothes
in there. Be ready to report out to the class.
Law of Superposition (Laundry Law)
 Law of Superposition Video (show first 3 mins)
 With your partner, explain how you could
determine how long clothes have been in a
laundry hamper as related to other clothes
in there. Be ready to report out to the class.
Absolute Dating
 Getting a near exact date of a rock or
fossil.
Radiometric Dating
 Some rocks are radioactive when created. These
rocks become stable at a constant rate, known as
half-life: (the time it takes for half of a radioactive
sample to become stable)
 For example, Uranium 238 (U-238) has a half life of
5 billion years. In that time, half of the sample
would be radioactive U-238 and the other half would
be U-234 (which is non-radioactive called “stable”).
 4 min video
Radiometric Dating continued…
 Uranium has a half life of
 Example: Scientists find
5 billion year.
 By looking at the
percentage of U-238 and
U-234, one can
determine how old the
sample is…and infer how
hold the fossils are
around it, in it, or in the
same layer.
a rock sample that is 75%
radioactive U-238 and
25% stable U-234.
Radiometric Dating: Carbon Dating
Carbon Dating of Fossils
 Carbon 14 is a radioactive form of Carbon that
occurs naturally.
 When an organism dies the amount of Carbon 14
in the bones slowly decreases.
 The “half-life” of Carbon is 6,000 years.
(Approximately every 6000 years half of the
Carbon 14 is converted to N-14.)
 How old would an organism be if it was found to
have 25% Carbon 14 and 75% N-14? Explain
Sample problems Carbon (6,000 year half-life)
 1) How old is a sample that is 25% stable and 75%
radioactive? Show your work.
 2) How old is a sample that is 12.5% radioactive and
87.5% stable? Show work.
 3) How old is a sample that is 6.25% stable and
93.75% radioactive? Show work.
Few more Radiometric Problems
 Potassium has a half life of 1.3 billion years.
 1) How old is a sample of this that is 75%
radioactive?
 2) ….25% radioactive?
 3) 6.25% stable?
 SHOW ALL YOUR WORK!
Evidence for Evolultion 2#) EMBRYOLOGY
 Scientists compare how organisms develop from embryos
(fertilized eggs) until they become adults.
 By comparing the changes that the embryos go through,
it can be determined how closely organisms are related.
 Example: All vertebrates have a tail and gill pouches at
some point in their development so they had a common
ancestor.
Evidence for Evolution
3) COMPARATIVE ANATOMY
 The anatomy of different organisms are compared
to see relationships
 Homologous structures- structures that similar in
two or more species Homologous Video
 Example: Arm bones of many vertebrates have the
same arrangement. (See book pg 384)
 Vestigial Structures- structures that are “left over”
from the past and have no clear function. Example
appendix Vestigial Structure Video
Comparative anatomy (cont…)
 Both shared structures and vestigial structures infer
a common ancestor.
 Vestigial structures show species have change from a
time when they need them.
 Shared structures show we came from the same
genetic line (passed down the line)
4)MOLECULAR & BIOCHEMISTRY
 ***THE BEST EVIDENCE FOR EVOLUTION
 Comparing the DNA and proteins of organisms for the
number of differences
 The differences are usually caused by some type of
mutation
 The fewer the number of differences the closer the
relation between the organisms
 (See slide #29, Part 5)
Molecular & Biochemistry (cont…)
 This area also implies that organisms share
common ancestors. In fact, all life we’ve ever know
shares the same DNA make-up (remember A-T, GC? It’s in all living things)
 5 minute video
Phylogenic (Phylogenetic) Tree
 Way to show relatedness of species by indicating
common ancestors.
 Can show present day organisms as well as those
that have gone extinct. 6 minute video
Example of a phylogenic tree:
RATE OF EVOLUTION
 Gradualism-Slow consistent change over a long
period of time (we used to think this)
 Punctuated Equilibrium-Long periods of little or no
change, followed by a short period with a lot of
change. (current theory)
GENETIC DRIFT
 GENETIC DRIFT: When a random (not natural
selection) event changes the make-up of the alleles
frequency in a population.
 Example: a group of ducks in a lake are killed by a
fiery airplane crash. Those that survive were just
lucky. “Stuff Happens”!
 NOTE: By having high variety among individuals,
species have a better chance of surviving these.
Bozeman 12 min video (start at around 5:00 min)
Nonrandom Mating (Mate Choice)
 When we mate with individuals like ourselves we
change the allele frequency to become more ……
 A mate is usually chosen based on certain traits
 Random mating would
be like pollen in flowers.
“Not-on-the-Test” Evidence:
Biogeography
 Different continents with similar biomes have
similar organisms.
 Examples Rhea, Ostrich and Emu
 This suggests that similar environments shape the
evolution of organisms in similar ways.
Ostrich
Emu
Rhea
Beyond Darwinian Theory
FORCES THAT CHANGE ALLELE
FREQUENCIES
MICROEVOLUTION
Allele Frequency
 Allele Frequency-The percentage of dominant,
recessive, co-dominant, or incompletely
dominant alleles that appear in a population
 The number of each allele does not
change unless an evolutionary force is
acting on it.
Evolutionary Forces That Change Allele
Frequency
 Each of the following cause the allele frequency to





change
Mutation
Gene flow (migration)
Nonrandom mating (mate choice)
Genetic drift
Natural selection
Mutations
 One allele turns into another by a mutation in the
genetic code
 Does not occur very often and are usually lethal
 Occurs 1-10 times per 100,000 cell divisions
Mutations
 Changes that happen in one generation
 May occur by a change in either the egg or sperm of a
parent
 May be caused by a virus, toxic chemical, drug,
bacteria or radiation
 May be caused by an error in cell division
Gene Flow (Migration)
 The movement of genes (alleles) from one
population to the next
 Migration


Immigrants - bring in new alleles to a population
Emigrants – take alleles out of a population
Genetic
 Small populations and/or isolation
 In small populations if a catastrophic event occurs
one of the allele frequencies could be reduced
 If individuals are “trapped” on an island, one of the
allele frequencies could be reduced
Divergent Evolution
 Divergent Evolution - is the process of two or more
related species become more and more dissimilar but
share same ancestor.
 3 minute video
More Divergent Evolution
Convergent Evolution
 Convergent Evolution - unrelated species become
more and more similar as they adapt to the same
environment
2 minute example of canine teeth
Convergent Evolution
Coevolution
 Coevolution - the joint change of two or more species
in close interaction.
 Often predator and prey
 8 minute Bozman Science
Extinction and Extripation
 Extinction: If all the members of a species is not
longer found on Earth.
 Extripation: All members of a species in a given
geographic location are no longer in that area.
Dodo Bird