DO NOW
• Each PAIR should take one white cloth and
one cup of beans from the back desk.
• Make sure you have 20 white beans and 20
brown beans.
Class Results
Number of Brown Beans
Picked
Number of White Beans
Picked
Total
Total
Changes Over Time
Chapter 6
Mutations
Section 1: Darwin’s Theory
Evolution:
• The process in which inherited characteristics
within a population change over generations
such that new species sometimes arise.
To Understand Darwin:
• Species: A group of organisms that are closely
related and that can mate to produce fertile
offspring.
• Variation: A difference in characteristics, or
traits among members of the same species.
• Adaptation: A characteristic that improves an
individual’s ability to survive and reproduce in
a particular environment
Charles Darwin
• In 1831, a 22 year old named Charles Darwin
served as a “naturalist” on the HMS beagle
during it’s 5-year trip around the world.
Charles Darwin
Charles Darwin
• Darwin’s important discoveries included the
diversity of living things, the remains of
ancient organisms, and the characteristics of
organisms of the Galapagos Islands.
• Darwin's Voyage
Finches
Tortoises
Charles Darwin
Natural Selection:
• The process by which individuals that are
better adapted to their environment survive
and reproduce more successfully than less
well adapted individuals.
• Natural Selection is a theory to explain how
evolution happens.
Natural Selection
1. Overproduction – more young
are born than can survive.
Natural Selection
2. Inherited Variation – there are
differences within the genes of every
population or species ( the result of
random mutation and translation errors)
Natural Selection
3. Struggle to Survive – Because of the
overproduction, there is a competition
for limited resources. Some individuals
are better suited to survive as a result
of variation.
Natural Selection
4. Selection– Darwin proposed that
over a long time, natural selection can
lead to change. Helpful variations will
gradually accumulate in a species,
while unfavorable ones may disappear.
Natural Selection
Successful Reproduction – Those
individuals with adaptations that made
them more “fit”, survive and pass those
traits on to their offspring. Therefore those
traits become more common in the
population.
Natural Selection
4. Successful Reproduction – Those individuals
with adaptations that made them more “fit”,
survive and pass those traits on to their
offspring. Therefore those traits become more
common in the population.
DO NOW
• Take out your finches homework. MAKE SURE
YOUR NAME IS ON IT. Put it in the class folder.
• Take a number from the back desk.
• Find the station with the matching number
and work together with other students in that
group to answer the question. (answers will
be shared with the class)
1. Who was Charles Darwin, and what did he do on the Beagle’s voyage?
2. What is evolution?
3. Explain how the shape of a finch’s beak is an example of an adaptation.
4. When members of a species compete, what do they compete for?
5. What happens when species overproduce offspring?
6. Suppose a variation makes an individual member of a species better adapted to its
environment. How might that variation affect the individual’s reproduction?
7. How does the environment “select” organisms?
8. How do helpful variations accumulate in a species over time?
9. Why can only traits controlled by genes be acted upon by natural selection?
Myth 1
Myth 2
Katherine
Katie
Hailey
Annesha
Ryan Drum
Peter
Vincent
Matt P
Aiden
Rachel
Myth 3
Myth 4
Ryan K
Nate
Elizabeth
Emily
Sam
Matt N
Margo
Liam
Naila
Veronica
James
Mike
Myth #1
If a four legged animal walked on
its hind legs enough, then it’s
offspring would be more likely to
be born able to also walk on it’s
hind legs.
Myth #2
Since evolution is just a theory, it is
no more likely to be true than any
other guess.
Myth #3
Since nobody actually saw it
happen, you can’t be sure that
evolution actually goes on.
(There is no real evidence to back it up.)
Myth #4
Human evolved from monkeys.
Before you go…
• Write a one-two sentence statement that
appropriately uses all three of the following
terms (in any order):
Variation
Adaptation
Environmental Pressure
• Write your answer on the index card and hand it to Mrs. Burke on your
way out.
Class Data
Beak
Spoon
Binder Clip
Tweezers
Scissors
Paper Clips
Rubber
Bands
Toothpicks
Macaroni
Index cards
DO NOT TOUCH ANYTHING IN THE LAB STATIONS OR MOVE THE STOOLS
Do Now
What variations exist among the to cacti in the picture?
Which is an adaptation and why?
Section 2: Evidence of Evolution
Interpreting the evidence
• Fossils, patterns of early development, and
similar body structures all provide evidence
that organisms have changed over time.
Evidence of Evolution
The Fossil Record
• Fossils provide an actual record of Earth’s past
life forms.
• By dating the rocks in which fossils are found,
we can arrange the fossils in order from oldest
to youngest and see patterns of inheritance.
Evidence of Evolution
The Fossil Record
Evidence of Evolution
Homologous Structures
• Similarities in different organisms body
structures provides evidence that those
organisms evolved from a common ancestor.
• Similar structures that related species have
inherited from a common ancestor are known
as homologous structures.
• (same structure, but different function)
Evidence of Evolution
Homologous Structures
Homologous structures show how similar structures have
evolved to have different functions in different species.
Evidence of Evolution
Vestigial Structures
• Sometimes bones are present in a organism,
but are reduced in size and either have no use,
or a less important function than they do in
other related organisms.
• These structures are known as vestigial
structures.
Evidence of Evolution
Vestigial Structures
Evidence of Evolution
Vestigial Structures
Evidence of Evolution
Similarities on DNA
• Comparing the DNA of different species can
show how closely related they are.
• The more similar the DNA sequence, the more
closely related the species are.
The sequences of human and chimpanzee DNA are 81-98 % identical!
Combining Evidence
• Scientists combine all of these different types
of evidence of species relationships and use it
to create branching trees.
Branching Trees
• Branching trees are diagrams that show how
scientists think species are related.
Common Ancestry
Common Ancestry
The Tempo of Evolution
• Gradualism: gradual change over a long
period of time leads to species formation.
• Punctuated Equilibrium: Periods of rapid
change in species are separated by periods of
little or no change.
(Successful species may stay unchanged for long period of time.
Major environmental changes may cause evolution to occur in
spurts.)
How Do New Species Form?
• Speciation: the process by which new species
form.
How Do New Species Form?
• A new species can form when a group of
individuals remains isolated from the rest of
the species long enough to evolve different
traits.
How Do New Species Form?
Do Now
What types of evidence do scientists use to determine evolutionary relationships
among groups?
Compare the flipper of a seal to the wing of a bird…
Think about the answers to these questions and discuss your ideas with
your partner. In three minuets you will share with the class…
• What do scientists infer from the similarities between these two
structures?
• What do scientists call such similar structures?
• Describe how DNA evidence might be used to confirm scientists’
conclusions about any relationship between birds and seals.
• What do similarities in the early development of organisms suggest?
Looking at the Evidence
Homologous vs. Analogous
Homologous: similar structures
although they have different
functions in the different
organisms.
Analogous: The structures are
different, although they serve the
same function for the organisms.
Looking at the Evidence
Homologous vs. Analogous
• Homologous Structures were inherited from a common
ancestor, so they still resemble each other even though they
are being used for different functions. (same structuredifferent function)
• Analogous Structures resemble each other externally because
they are being used for similar functions in a similar
environment, but they are not actually that similar in
structure internally because they were not inherited from a
common ancestor. (same function – different structure)
Looking at the Evidence
Vestigial Structures
Looking at the Evidence
DNA Sequence and Embryo Development
Adaptation of the Human Hand
• One of humans’ adaptations that has given us
a great advantage over other animals is our
opposable thumb, which allows us to grasp
objects.
• Today’s lab will demonstrate how the human
hand is adapted to the actions it performs.
The Mystery Fossil Bones
Activity
DIRECTIONS:
1. On your desk you will find a set of mystery bones. Every group
member should help cut out the mystery fossil bones.
2. Then your group will brainstorm ideas on how you think the
bones go together. You may try multiple rearrangements until
the group agrees on a final bone structure for the mystery
organism.
3. Once you have agreed, glue the bones on to the large piece of
paper that was provided for you at your station.
4. Next your group must decide what the outside of the animal
looked like. Was it covered with skin, fur, scales, something
else? How large was it? What did it eat?
5. Add these details to your groups poster.
VOCABULARY
Evolution
• The process in which inherited
characteristics within a population change
over generations such that new species
sometimes arise.
Adaptation
• A characteristic that improves an individual’s
ability to survive and reproduce in a
particular environment
Variation
• A difference in characteristics, or traits
among members of the same species.
Species
• A group of organisms that are closely related
and that can mate to produce fertile
offspring.
Homologous Structures
• Similar structures that related species have
inherited from a common ancestor. (same
structure, but different function)
Analogous Structures
• Structures that resemble each other
externally because they are being used for
similar functions in a similar environment,
but they are not actually that similar in
structure internally because they were not
inherited from a common ancestor. (same
function – different structure)
Vestigial Structures
• Structures that are present in a organism, but
are reduced in size and either have no use, or
a less important function than they do in
other related organisms.
Gradualism
• Gradual change over a long period of time
leads to species formation.
Punctuated Equilibrium
• Periods of rapid change in species are
separated by periods of little or no change.
Natural Selection
1. Overproduction – more young
are born than can survive.
Natural Selection
2. Inherited Variation – there are
differences within the genes of every
population or species ( the result of
random mutation and translation errors)
Natural Selection
3. Struggle to Survive – Because of the
overproduction, there is a competition
for limited resources. Some individuals
are better suited to survive as a result
of variation.
Natural Selection
4. Selection– Darwin proposed that
over a long time, natural selection can
lead to change. Helpful variations will
gradually accumulate in a species,
while unfavorable ones may disappear.
Homologous
same structure – different function
Analogous
same function – different structure
Vestigial
VARIATIONS
•
•
•
•
•
•
Shell size and shape among the tortoises
Length of individual tortoises’ legs
Different Shell Colors and Patterns
Amount of blubber each penguin has
Penguin Height
Length of Penguin Beaks
Adaptations
• Longer legs on a tortoise.
• High arching shells that sit far back on the
shoulders.
• A gene mutation that increases the amount
of blubber a penguin has.
• Markings that make an individual attractive
to the opposite sex.
Environmental Pressures
•
•
•
•
•
•
Drought
Location of the food supply
Predators
Competition for mates
Extreme Temperatures
Limited Habitat Space
Essay:
• Darwin said “It is not the strongest of the
species that survive, nor the most intelligent,
but the one most responsive to change.” How
do genetics and evolution work together to
allow certain species to change while others
become extinct?
Your Essay Should Include:
• All offspring inherit their DNA from their parents.
• Genes are carried from parents to offspring on chromosomes.
• Because of this no two members of the same species are
genetically identical. (variation)
• Within any population, there will be overproduction causing a
struggle to survive when members of the same species have
to compete for limited resources.
• Because of the variations that the offspring inherited from
their parents, some will be better at getting those limited
resources than others (adaptation)
• These better adapted individuals will be more likely to survive
and reproduce, passing on the adaptations to their own
offspring.
• Over time the better adapted traits will build up in the
population and the species will slowly change. (evolution)