Download Evolutionary Classification

Sz2- Students will explain the evolutionary history of
animals over the geologic history of Earth.
Geologic History

Geologic time- time that began when earth was
formed until present day
Evolution of the Earth with Time: Continental Drift
50 Million Years Ago
200 Million Years Ago
150 Million Years Ago
100 Million Years Ago
Present
Important Terms
Evolution- gradual change in a species over
time- sci. theory
 Theory-well-tested explanation that
explains a wide range of observations.
 Adaptation- any trait that helps an
organism survive and reproduce

Natural Selection

the process by
which individuals
that are better
adapted to their
environment are
more likely to
survive and
reproduce.
Charles Darwin
Natural Selection cont.
 Over
a long time, natural
selection can modify a
population enough to produce
a new species
 Helpful variations accumulate
in a species while unfavorable
ones disappear.
Speciation
 When a group of individuals remain
separated from the rest of the species long
enough to evolve different traits
HOW this happens-
 Pangaea /Continental Drift
 Landform isolation- river, mountain, water.
(ex. Squirrels of N. Grand Canyon)
 Australia
A Problem with Traditional Classification

Traditional classification systems relied on
body structure comparisons only

Due to convergent evolution, organisms that
are quite different from each other evolve
similar body structures.
Convergent Evolution:
Process by which
unrelated organisms independently evolve
similarities when adapting to similar environments.
A Problem with Traditional Classification
Example: The Crab, The barnacle, & The limpet
•
The barnacle and the limpet have similarly shaped
shells & look alike
•
The crab has a very different body form
•
Based on anatomy, the barnacle & limpet could be
classified together and the crab in a different
group.
Related
This incorrect because
crabs and barnacles
are actually related
Traditional Classification Versus Cladogram
Section 18-2
Appendages
Crab
Conical Shells
Barnacle
Limpet
Crustaceans
Crab
Gastropod
Barnacle
Limpet
Molted
exoskeleton
Segmentation
Tiny free-swimming larva
TRADITIONAL
CLASSIFICATION
Go to
Section:
CLADOGRAM
12
Crustaceans
Gastropods
Molted Exoskeleton
Segmentation
Free swimming Larva
Even though they do
not look a like, crabs &
barnacles are actually
related
Evolutionary Classification

Biologists now group organisms into categories
that represent lines of evolutionary descent, not
just physical similarities
Evolution Classification:
Is the strategy of
grouping organisms together based on their
evolutionary history.
Genus species
If these three species belong to the same genus,
they are descended from a common ancestor.
Felis domestica
domestica
Felis
Domestic
Cat
Felis leo
leo
Lion
Felis margarita
margarita
Sand cat`
Classification Using Cladograms
Cladogram:
A diagram that shows the
evolutionary relationships among a group of organisms.
Crustaceans
Gastropods
Molted Exoskeleton
Segmentation
Free swimming Larva
Using Cladograms, you can
see that crabs and barnacles
share similar characteristics
because they both molt & are
segmented
Crustaceans
Gastropods
Molted Exoskeleton
Segmentation
Free swimming Larva
You can also see that
ALL have a free
swimming larval stage
Modern Evolutionary Classification

Similarities in DNA and RNA
 The genes of many organisms show
important similarities at the molecular
level that can be used as criteria to help
determine classification.
19
Modern Evolutionary Classification

Molecular Clocks
 A model known as a

Comparison reveals
more DNA in common,
the more recent the
common ancestor
molecular clock uses
DNA comparisons to
estimate the length of
time that two species
have been evolving
independently.
20
Terminology

Classification
 Assigning organisms to
different catagories based
on their relationship

Taxonomy
 The science of naming
organisms

Systematics
 Determining evolutionary
relationships of organisms

Phylogeny
 Evolutionary history
21
Phylogenetic Tree
Shows evolutionary
relationships
 More historical than
cladogram

22
Uniramia
Echinodermata
Chordata
Lophophorates Chelicerata
Crustacea
Protochordates
Arthropoda
Annelida
Hemichordata
Other
pseudocoelomates
Nematoda
Mesozoa
Sarcomastigophora
Ciliophora
Apicomplexa
Microspora
Mollusca
Nemertea
Platyhelminthes
Ctenophora
Cnidaria
Placozoa
Porifera
Myxozoa
23
Birds
Mammals
Reptile
Feathers
Amphibian
Fish
Fur
Endothermic
Amniotic Egg
Four Limbs
Vertebrae
24
Monophyletic
A group of all the
descendants of a
common ancestor
 The common
ancestor is in the
group
 Example: Birds and
Reptiles

 Ancestor was a bird
like reptile
25
Polyphyletic
group that has some
similarities
 Contains organisms that
have not descended from
a common ancestor
 Based on physical
characteristics instead of
evolutionary evidence
 Example: Flying
vertebrates- pterosaurs,
birds, mammals

26
Cladogram
Evolutionary
relationship of a
group of organisms
 Each clad (group)
share something in
common
 Ancestral traits are
the oldest
 Derived traits evolved
later

27
Cladogram for Transportation
Wheels are the most
ancestral
 Wings are the most
derived

28
Construct a Cladogram
29
Gorilla
Four limbs
 Fur
 Lost tail

30
Tiger
Four limbs
 Fur
 Tail

31
Lizard
Four limbs
 Tail

32
Fish

Tail
33
Chimpanzee
Four limbs
 Fur
 Lost tail

34
Clad With 4 Limbs
35
Clad With Fur
36
Clad With No Tail
37
Characteristics for Constructing
Cladogram
Tail is the most ancestral
 Four limbs is the oldest derived trait
 Fur is a later derived trait
 Loss of tail is the most derived trait

38
Gorilla
Chimpanzee
Tiger
Lizard
Fish
Tail Lost
Fur
Four Limbs
39
Gorilla Tail?

How do we know the
gorilla lost its tail?
40
Gorilla’s Vestigial Tail
Gorilla
Human
41
The End.