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EVOLUTIONARY CLASSIFICATION Sz2- Students will explain the evolutionary history of animals over the geologic history of Earth.
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
200 Million Years Ago
150 Million Years Ago
100 Million Years Ago
50 Million Years Ago
Present
Evolution of the Earth with Time: Continental Drift
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.
SpeciationWhen a group of individuals remain
separated from the rest of the species long enough to evolve different traits
How Speciation OccursGeographic isolation-
○ Pangaea /Continental Drift○ Landform isolation- river, mountain,
water. (ex. Squirrels of N. Grand Canyon)
Competition Gene flowEnvironmental change- local
adaptation to local environment
Speciation of Squirrels- Grand Canyon
The Kaibab squirrel (Sciurus aberti kaibabensis, left) became isolated in the Grand Canyon ~ 10,000 years ago. Features have gradually evolved that separate it from close relative, the Abert squirrel (S. aberti aberti)
A Problem with Traditional ClassificationExample: 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
Crustaceans
Even though they do not look a like, crabs & barnacles are actually
related
Gastropods
Molted Exoskeleton
Segmentation
Free swimming Larva
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.
Modern Evolutionary Classification
Evolutionary Classification: Is the strategy of grouping organisms together based on their evolutionary history, instead of physical features.
Uses DNA and RNA, embryological development, comparative anatomy to classify species.
Modern Three-Domain System As scientists further analyzed cell structure and DNA , a
broader category was added- The domain is the most inclusive taxonomic category;
larger than a kingdom The three domains are:
Bacteria : kingdom Eubacteria
Archaea,: kingdom Archaebacteria;
Eukarya :Kingdom Protista, Fungi, Plantae, and Animalia.
If these three species belong to the same genus, they are descended from a common ancestor.
Genus species
Felis
domestica
leo
margarita Sand cat`
Lion
Domestic Cat
Felis domestica
Felis leo
Felis margarita
Classification Using CladogramsCladogram: A diagram that shows theevolutionary relationships among a group of organisms.
Derived trait- new traits that show up in a lineage ex. jaws, lungs, mammary glands
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Modern Evolutionary Classification
Molecular Clocks
A model known as a molecular clock uses DNA comparisons to estimate the length of time that two species have been evolving independently.
Comparison reveals more DNA in common, the more recent the common ancestor
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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
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Phylogenetic Tree Shows evolutionary
relationships More historical than
cladogram
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Myxozoa
Arthropoda AnnelidaMollusca
Lophophorates
Hemichordata
Chordata
Other pseudocoelomates
Nematoda
Porifera
CtenophoraCnidaria
Placozoa
PlatyhelminthesNemertea
CiliophoraSarcomastigophora
MicrosporaApicomplexa
Mesozoa
Echinodermata
CrustaceaChelicerata
Uniramia
Protochordates
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Birds MammalsReptile
AmphibianFish
Four LimbsAmniotic Egg
EndothermicFur
Feathers
Vertebrae
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Monophyletic groups (Clades)
A group of all the descendants of a common ancestor
The common ancestor is in the group
Example: Birds and ReptilesAncestor was a bird
like reptile
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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
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Cladogram Shows Evolutionary
relationships of a group of organisms
Each clad (group) share something in common
Ancestral traits are the oldest
Derived traits evolved later
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Cladogram for Transportation
Wheels are the most ancestral
Wings are the most derived
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Construct a Cladogram
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Gorilla Four limbs Fur Lost tail
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Tiger Four limbs Fur Tail
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Lizard Four limbs Tail
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Fish Tail
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Chimpanzee Four limbs Fur Lost tail
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Clad With 4 Limbs
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Clad With Fur
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Clad With No Tail
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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
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Gorilla ChimpanzeeTiger
LizardFish
Four LimbsFur
Tail Lost
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Gorilla Tail? How do we know the
gorilla lost its tail?
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Gorilla’s Vestigial Tail
Gorilla Human
