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EVOLUTION
Mrs. Knopke
Fullerton Union High School
California State Standard
3. Biological evolution accounts for
the diversity of species developed
through gradual processes over
many generations.
c. Independent lines of evidence
from geology, fossils, and
comparative anatomy provide
the bases for the theory of
evolution.
Evolution
What is it?
Evolution
Simply stated, evolution is a
change in a lineage of
organisms through time.
Root Word - Evolut
An unrolling
Types of Evidence
for Evolution
Fossils
Comparative Anatomy
Embryology
Biochemistry
What is a Fossil?
 Any trace of an
organism that
lived long ago.
Paleontologists-Detectives to the past
 Paleontologists also study fossils to gain
knowledge about ancient climate and
geography.
 By studying the condition, position, and
location of rocks and fossils, geologists and
paleontologists can make deductions about
the geography of past environments.
Fossil formation
 For fossils to form,
organisms usually have to
be buried in mud, sand,
or clay soon after they
die.
 Most fossils are found in sedimentary rocks.
These rocks form at relatively low temperatures
and pressures that may prevent damage to the
organism.
Fossil formation
 Fossils are not usually found in other types of
rock because of the ways those rocks form.
For example, the conditions under which
metamorphic rocks form often destroy any
fossils that were in the original sedimentary
rock.
The Fossilization Process
 Few organisms become fossilized because,
without burial, bacteria and fungi immediately
decompose their dead bodies. Occasionally,
however, organisms do become fossils in a
process that usually takes many years.
The Fossilization Process
• Sediments from upstream
rapidly cover the body,
slowing its decomposition.
Minerals from the sediments
seep into the body.
• Over time, additional layers
of sediment compress the
sediments around the body,
forming rock. Minerals
eventually replace all the
body’s bone material.
• A Protoceratops
drinking at a river
falls into the water and
drowns
• Earth
movements or
erosion may
expose the fossil
millions of years
after it formed.
Relative dating
 Scientists use a variety of methods to determine
the age of fossils. One method is a technique
called relative dating.
 If the rock layers
have not been
disturbed, the
layers at the
surface must be
younger than the
deeper layers.
The Fossil Record
 Darwin’s views were influenced by fossils,
the relics or impressions of organisms from
the past, mineralized in sedimentary
rocks.



Sedimentary rocks form when mud and sand settle to
the bottom of seas, lakes, and marshes.
New layers of sediment cover older ones, creating
layers of rock called strata.
Fossils within layers show that a succession of
organisms have populated Earth throughout time.
Fig. 22.2
Fig. 22.4
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
 Fossils are the preserved remnants or
impressions left by organisms that lived in
the past.
 In essence, they are the historical documents
of biology.
 The fossil record is the ordered array in which
fossils appear within sedimentary rocks.

These rocks record the passing of geological time.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
 The organic material in a dead organism
usually decays rapidly, but hard parts that
are rich in minerals (such as bones, teeth,
shells) may remain as fossils.
 Under the right conditions minerals
dissolved in groundwater seep into the
tissues of dead organisms, replace its
organic material, and
create a cast in the
shape of the organism.
Fig. 25.1c
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
 Trace fossils consist of footprints,
burrows, or other impressions left in
sediments by the activities of animals.
 These rocks are in
essence fossilized
behavior.
 These dinosaur tracks
provide information
about its gait.
Fig. 25.1f
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
 Rarer than mineralized fossils are those
that retain organic material.
 These are sometimes discovered as thin
films between layers of sandstone or
shale.
 As an example, plant leaves millions of
years old have been discovered that are still
green with chlorophyll.
 The most common
fossilized material is
pollen, which has a
hard organic case
that resists
degradation.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Comparative Anatomy
Homologous Structures
homoSAME
Comparative Anatomy
Homologous Structures
Comparative Anatomy
 Not all similarity is homology…
 Remember: homologous =
common ancestor
Comparative Anatomy
Analogous Structures
ana- NOT
Comparative Anatomy
Analogous Structures
Mammals
Distant rat-like common ancestor
Comparative Anatomy
Analogous Structures
Comparative Anatomy
Vestigial Structures
TOP 10 Useless Limbs
(and other Vestigial Organs)
10. The wings on flightless birds.
9. Hind leg bones in whales and snakes.
8. Erector pili and body hair.
7. The human tailbone (coccyx).
6. The blind fish Astyanax mexicanus.
5. Wisdom teeth in humans.
4. Sexual organs of dandelions.
3. Mating behavior of virgin whiptail lizards.
2. Male breast tissue and nipples.
1. The human appendix.
http://www.livescience.com/animalworld/top10_vestigial_organs.html
Evidence from
Embryology
An Elephant Embryo
58 days old  166 days old
4 mm long  6 cm long
Comparative Embryology
Embryos
Comparative Embryology
A
Can you guess
fish
which embryo
belongs to…
B
bird
C
The human?
The fish?
pig
The pig?
D
The bird?
human
Biochemical Evidence
Looking at an organism
and the relationship
with other organisms at
the DNA level.
Evidence from Biochemistry
Amino acids and enzymes
(proteins)
Ex: Cytochrome c
Biochemical Similarities of Organisms
Comparison of Organisms
Two orders of mammals
Birds vs. mammals
Percent Substitutions
of Amino Acids in
Cytochrome c Residues
5 and 10
8-12
Amphibians vs. birds
14-18
Fish vs. land vertebrates
18-22
Insects vs. vertebrates
27-34
Algae vs. animals
57
Molecular Evidence
Molecular Evidence
Evidence from Biochemistry
On a molecular level,
the DNA code links
living organisms to
common ancestors.
Factoid: Roundworms share 25% of their genes with humans!
Evidence for Evolution
 Today, scientists combine data
from fossils, comparative
anatomy, embryology, and
biochemistry in order to
interpret the evolutionary
relationships among species.
Relative Age of Fossils
Radioactive Dating
 How to date a fossil (without
spending a fortune for dinner and
flowers) Have you wondered how the
age of fossils are determined? There
are several different methods scientists
use to determine age of fossils.
Sometimes, it is possible to determine
age directly from the fossil. Many times
however, fossils are to old to have their
age directly measured. Instead, age
can be determined from radioactive
elements occuring within rock found in
association with the fossils.
 Over time, radioactive “parent” isotopes
are converted at a steady decay rate to
“daughter” isotopes.
 The rate of
conversion is
indicated as the
half-life, the
time it takes
for 50% of
the isotope
to decay.
Fig. 25.2
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Mimicry
 How Does Mimicry Help Animals?
Usually, an animal will MIMIC another
to avoid predators. If it can
trick its enemy into thinking it is
something less tasty or more
dangerous, it will survive
 This tropical saturniid moth displays eyespots on
its hindwings when threatened. This is a
"dishonest" signal, in contrast to the "honest"
signal of the Io moth in the preceding image.
Mimicry
 A Lonomia moth
resembles a dead
leaf on the forest
floor of the
Monteverde Cloud
Forest in Costa
Rica, her head at
the left and a
simulated leaf vein
running from
wingtip to wingtip.
 In the lowland rain forest of the Peruvian
Amazon, a "bird dropping" on a leaf
turns out to be a caterpillar.
 Munching on a
plant stem in Costa
Rica's Monteverde
Cloud Forest
Reserve, this
Xylophanes
caterpillar has such
tiny eyes that you
would need a hand
lens to see them.
The red "eyes" and
pointed "stinger"
Camouflage
 A masked
treefrog seems to
be strumming a
stem as we watch
him on the slopes
of Costa Rica's
Penas Blancas
cloud forest
Camouflage
 An animal uses camouflage to blend in
with its environment. Camouflage is the
use of color, pattern, and shape to look
like the things around you
 A gravid female
katydid blends with
the tropical
vegetation in the
lowland Amazon
rain forest of Peru.
Her wings mimic
the mottling of the
surrounding leaves,
and she holds even
her long antennae
still as we take this
available-light
photo
Physiological Evidence
 A change in the organisms metabolic
processes:
 Weeds ability to become resistant to
herbicides.
 Bacteria’s ability to become resistant to
antibiotics.
 Venom of a snake
Structural Adaptations







Take many different forms –
Thorns
teeth
hair
beaks
color
Tails
Diversity in new environments
Extinct
mamo
Amakihi
Possible
Ancestral
Lasan finch
Crested
honeycreeper
Kauai
Niihau
Molokai
Oahu
Maui
Lanai
Akialoa
Kahoolawe
Akepa
Akiapolaau
Akikiki
Liwi
Hawaii
Apapane
Maui
parrotbill
Palila
Ou
Grosbeak
finch
Charles Darwin – Father of
Modern Scientific Thought
 Raised on a farm
 Was an avid
outdoorsman (fished
and hunted), collected
bugs, taxidermist
 Influenced greatly buy
his grandfather
Erasmus Darwin

Was a Physician,
Poet and early
Evolutionist
Charles Darwin – Father of
Modern Scientific Thought,
cont’d
 Family plans were to
have him become a
doctor like his
grandfather and father
 After 2 years of
Medical School he
dropped out

Operations were
bloody and had
problems with fainting
Charles Darwin – Father of
Modern Scientific Thought,
cont’d
 Parents sent him to
Divinity School for 3
years to become a
clergy in the Church
of England

Left because he
preferred to be
outdoors
 As any parent would
do, they worried about
what they were going
to do with their son



Charles Darwin – Father of
Modern Scientific Thought,
cont’d
Darwin’s Botany
professor at Cambridge
(John Stevens Henslow)
was contacted about a job
as a naturalist for a ship
He thought of Darwin for
the position
Because of Henslow’s
recommendation, Darwin
was hired as the
Naturalist aboard the
H.M.S. Beagle and as a
companion for Captain
Fitzroy

Charles Darwin – Father of
Modern Scientific Thought,
Darwin
had one major
cont’d
problem on the voyage



He was seasick for almost
the entire voyage
Because of this, every time
he had a chance to go
ashore, he did
While away from the ship,
he collected plants and
animals to send back to
England and made
meticulous drawings of
those he didn’t collect
Cape Verde
Islands
Galapagos
Islands
Lamarckism: Inheritance of
Acquired Traits
 “Organisms by striving to adapt to their
environment acquire adaptations during
their lives that are passed on to its
offspring”
 New parts from no parts and use disuse
 Pangenetic view of development
 “Gemules” modify the preformed embryo in
the males sperm
Inheritance of Acquired
Traits
 Observation #1: All
species have such great
potential fertility that their
population size would
increase exponentially if all
individuals that are born
reproduced successfully.
Fig. 22.8
 Observation #2:
Populations tend to remain
stable in size,
except for seasonal
fluctuations.
 Observation #3: Environmental resources are
limited.
 Observation #4: Individuals of a population
vary extensively in their characteristics; no
two individuals are exactly alike.
Fig. 22.9
 Observation #5: Much of this variation is
heritable.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
•Inference #1: Production of more individuals than
the environment can support leads to a struggle for
existence among the individuals of a population,
with only a fraction of the offspring surviving each
generation.
 Inference #2: Survival in the struggle for
existence is not random, but depends in
part on the hereditary constitution of the
individuals.
 Those individuals whose inherited
characteristics best fit them to their
environment are likely to leave more offspring
than less fit individuals.
 Inference #3: This unequal ability of
individuals to survive and reproduce will
lead to a gradual change in a population,
with favorable characteristics accumulating
over the generations.
Causes of Genetic
Variation in a Population
 Recombination
 Gene Flow - Migration
 Genetic Drift
 Mutations
Causes of Genetic
Variation in a Population
 Recombination
 Gene Flow – Migration
 Genetic Drift
 Mutations
Gene Flow
 The loss or gain of alleles in a population
due to the migration of fertile individuals
or gametes between populations.
 If too much gene flow, populations become
homogeneous
Gene Flow
6 Red : 4
White
10 Red : 0 White
Gene Flow
10 Red : 0
White
10 Red : 2 White
Causes of Genetic
Variation in a Population
 Recombination
 Gene Flow - Migration
 Genetic Drift
 Mutations
Genetic Drift
 Changes in the gene pool of a small
population due to chance.
 Important to small populations.
 The Founder Effect
 New colony being populated by a few
individuals

Important on islands
 The Bottleneck
 Diseases or other catastrophes cause the
population to dramatically decrease in numbers
Genetic Drift
 A change in a population’s allele
frequency due to chance. Important to
small populations.
 The Founder Effect
 New colony being populated by a few
individuals

Important on islands
 The Bottleneck
 Natural catastrophes cause the population to
dramatically decrease in numbers
The Bottleneck
The Bottleneck
Flood kills
most of
the
individual
s
The Bottleneck
Causes of Genetic
Variation in a Population
 Recombination
 Gene Flow - Migration
 Genetic Drift
 Mutations
Mutations
Mutations:
Any change in the genetic
sequence of DNA
 Most Mutations are Neutral
 Replicational repair
 Redundancy in genetic code
 Intron/Exon formation in mRNA
 Masked by dominant gene
 On average, mutations occur 1 out of a
billion base pairs; thus we carry 3 mutations
in our genetic code
Mutations:
Any change in the genetic
sequence of DNA
 Most Mutations are Neutral
 Replicational repair
 Redundancy in genetic code
 Intron/Exon formation in mRNA
 Masked by dominant gene
Genetic Redundancy
Genetic Redundancy
MetSerValStop
AUGUCAGUUUAG
Mutations
AUGUCAGUAUAA
MetSerValStop
Mutations:
Any change in the genetic
sequence of DNA
 Most Mutations are Neutral
 Replicational repair
 Redundancy in genetic code
 Intron/Exon formation in mRNA
 Masked by dominant gene
Introns/Exons
Mutations:
Any change in the genetic
sequence of DNA
 Most Mutations are Neutral
 Replicational repair
 Redundancy in genetic code
 Intron/Exon formation in mRNA
 Masked by dominant gene
Sickle-cell Anemia





First described by a
Chicago MD in the early
1900’s.
Caused by a SINGLE
mutation (change second
base of the codon from
uracil to adenine – from
valine to glutamate) at the
sixth position of the beta
chain.
Causes the hemoglobin
molecule to lose their
flexibility and become
rigid.
Under low oxygen
condition, the RBC will
become sickle in shape.
These sickled RBC are
then destroyed.
Sickle-cell Anemia



A recessive gene that
follows “Mendelian
Inheritance”.
Homozygous recessive
condition is “Sickle-cell
Anemia” with only a
20% chance of
surviving to puberty.
Heterozygous
condition is “Sicklemia”
and individuals will
only become ill under
extreme conditions,
e.g. high altitudes,
exertion.
Three Forms of Natural
Selection
 Stabilizing
 Directional
 Disruptive
Stabilizing Selection
Directional Selection
Disruptive Selection
Allopatric Speciation
From Ricklefs, R.E. 2001. The Economy of Nature. W.H. Freeman. New York.
Mammals
Distant rat-like common ancestor
What happens when 2
“new” species come in
contact again?
 Post-zygotic Barriers
 Pre-zygotic Barriers

Which ones happen are a function of time
 Once these types of barriers are in place, two
species can overlap in space, and remain true
biological species
Post-zygotic barriers
 Hybrid sterility - hybrids
can't produce functional
gametes
 Hybrid breakdown - hybrids
never reach sexual maturity.
 Hybrid inviability - offspring
of hybrids are inviable.
Time
Increasing
Pre-zygotic Barriers





Time Increasing
Gametic isolation - gametes fail
to unite
Structural isolation - mating is
physically impossible
Behavioral isolation - mates
recognize species specific sexual
signals
Temporal isolation - mating
occurs at different times.
Habitat isolation - mating occurs
in different places
Adaptive Radiation –
Produces Homologous
structures
A Common Ancestor
Convergent RadiationSpecies that are not
closely related have
similar traits in similar
environments
Homology or analogy?
You have probably noticed that dolphins and sharks both have a
streamlined body shape with a triangular fin on the back and
two side fins. However, the two animals also have many
differences.
Sharks
Dolphins
skeleton made of cartilage
skeleton made of bone<>
use gills to get oxygen from the water in
which they swim
go to the surface and breathe atmospheric
air in through their blowholes
don't nurse their young
do nurse their young
don't have hair
do have hair — they are born with hair
around their "noses"
They may share the same basic
shape, but underneath their skins,
sharks and dolphins are very
different!