Supporting Evidence for
Evolution
Evolution evidence does not make
sense unless there is an awareness
of differences between living
organisms
process of organizing and classifying
organisms into certain groups by their
differences is called taxonomy
 Taxonomy comes from a root Greek word
meaning “order” or “arrangement”

Taxonomic Classification: biological
classification
classification; placing of similar objects
into similar groups
 Biological classification organizes all living
organisms


Structure, DNA, cell type, complexity, etc.
History of Classification
developed by Swedish scientist
Carolus Linnaeus in the 18th
century
 Designed to have a universal
naming system
 binomial nomenclatureorganism's scientific name is
comprised of a combination of
two terms: genus and species


scientific name for humans- Homo
sapiens
Reason for universal naming system

Name this animal
Common name: PUMA, MOUNTAIN LION, COUGAR
Scientific Name: Felis concolor
Classification
DOMAIN
•Domain is the most broad while species is the most specific
•Mnemonic:
o dear king phillip came over for good soup
Classification
Structures, functions and genetics help
support the theory of evolution

Convergent evolution vs Divergent evolution
Homologous Structures
Analogous Structures
Vestigial Structures
Embryology
Genetic similarities

Atavisms





*Other supporting evidence: fossil records, relative/absolute dating
Convergent evolution
Convergent evolution:
unrelated pathways to
different species develop
similar traits.
 Similar traits develop due to
similar environmental
pressures.

These traits
can be called
analogous traits
Analogous Traits

Different structures with the same function
Divergent evolution
opposite of convergent evolution
 related pathways can develop
different traits over time:

Natural selection, sexual selection,
genetic barriers and mutation drive
these changes.
 enough small changes accumulate in
closely related but isolated
populations, speciation might occur

Homologous Traits

Same structure
but different
function

characteristics
that derive from
shared common
ancestry
Vestigial Structures (vestigial organ)
Many organisms possess vestigial
structures
 no apparent function, however; they
resemble structures their presumed
ancestors had

Structures were once important
 Through evolutionary change the structures
became useless

Vestigial structure examples
Humans-possess a complete set of
muscles for wiggling their ears
 human appendix is believed to be vestigial;
it represents the terminal part of the cecum

Vestigial Structures

Boa constrictors have hip bones and
rudimentary hind legs
Vestigial Structures

Manatees, a type of aquatic mammal,
have fingernails on their fins (which
evolved from legs)
Vestigial Structures

Baleen whale, which contains pelvic bones, as
other mammal skeletons do, even though such
bones serve no known function in the whale.
Do Now Questions
1. Which organism has the closest relationship
to Panthera leo? How do you know?
a. Felis concolor
b. Panthera tigris
c. Equus caballus
d. Canis lupus
2. Which format for scientific name is correct?
a. danaus plexippus
c. Danaus Plexippus
b. Danaus plexippus
d. Danaus plexippus
Embryology


study of embryos
 formation, development, structure and function
An embryo is an organism in its early stages of
development
Comparative Embryology

Comparing stages of early development from very different
animals provides evidence for commonality
Genetic Similarities (molecular homology)


Technology has allowed us to examine the DNA
and protein structures/patterns from any
organism in existence
Comparing different species DNA can
undercover similarities and differences
 How closely related are these organisms?
Genetic Similarities


protein:
hemoglobinWho are humans
closest relative
using
hemoglobin
testing?
Human Beta Chain
0
Gorilla (greater ape)
1
Gibbon (lesser ape)
2
Rhesus monkey
8
Dog
15
Horse,cow
25
Mouse
27
Gray kangaroo
38
Chicken
45
Frog
67
Lamprey
125
Sea slug
127
Soybean (leghemoglobin) 124
How similar are we when
comparing DNA?
Another human?
~99.9%
A chimpanzee?
~97-98%
A mouse?
~90%
A fruit fly?
~45%
Yeast?
~25%
Genetic Similarities
Genetic Similarities

Humans
chromosomes vs.
chimpanzees
chromosomes

Chromosome #2
fused
Atavism

reappearance of a trait or characteristics in an
organism that is typical of an ancestral form
(appearing trait has been absent from modern organism for many
generations)

usually due to mistake in reading DNA
 Expressing “junk DNA”

Atavism can be seen in many different
organisms
Atavisms

Human Atavisms
Cladogram
A tree-like diagram which shows the
evolutionary relationship between
organisms
Reading and constructing a
cladogram
vertebrae
legs
hair
Opposable
thumbs
jellyfish
lamprey
X
salamander
X
X
cat
X
X
X
X
X
X
gorilla
X
cat
gorilla
salamander
lamprey
Opposable thum
hair
jellyfish
legs
vertebrae
time
What can a cladogram tell you?
•Common ancestor
•Closest relative
•Distant relative
Speciation event
Punctuated equilibrium and
gradualism
Do Now
Fill in the chart and create a
cladogram.
jaws
Lizard
Tiger
Human
Salamander
Lamprey
shark
gorilla
lungs Amiontic
sac
hair
thumbs bipedal
Who is classified as a primate?
an animal order (classification) including lemurs,
tarsiers, monkeys, apes and human beings
Primate Cladogram
New fossil evidence!
•Oldest primate
ancestor was
thought to be 60
mya
•New primate
ancestor foundabsolute dating puts
its age at around 85
mya
BBC news: http://news.bbc.co.uk/2/hi/science/nature/1935558.stm
Earliest primate found thus far (85 myo
)
Closer look at an ape
cladogram
See video**
Comparing humans to great apes…
Comparing humans to great apes
Primate Hand
Comparing humans to great apes
Genetic
comparison:
Humans and
chimpanzees are ~97%
similar in their genetic
composition
Large difference- # of
chromosomes
See video**
What happened after the
speciation event where chimps
and humans diverged?
•Environmental
conditions that
lead to
chimpanzees:
tree-dwellers
•Environmental
conditions that
lead to humans:
ground-dwellers
The modern human was not
always this way…
See video**
Modern
human
skull
Evolution of humans
Evolution of humans
Lucy (3.2mya) and Ardi (4.4mya)
*Oldest fossils all found in Africa*
Species are arranged according to the earliest date of fossils found so far
( a couple of recent discoveries are not shown). The red lines end
because fossils have not been found any older for that species.
**Note the overlap of time for species**
The oldest fossils in the evolution of humans
have only been found on the continent of Africa,
no where else.
•Who is the closest relative to humans?
•Is that relative alive today?
Specialized Characteristics:
•Depth perception (distance of an object)
•Binocular vision (using both eyes together)
•Social complexity (groups, communication)
•Opposable thumbs, grasping
fingers
•Cranial capacity (size of brain; humans have the
largest capacity)
•Bipedalism (walking on two feet; strictly a human trait)
Why is this picture incorrect?
Evolution and the world
Can evolution be observed
today?
YES IT CAN! Some bacteria
and viruses evolve at a very
fast pace.