Transcript 18-2 Modern Evolutionary Classification

The Tree of Life
Modern Evolutionary
Classification
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Problems With Traditional Classification
Appearances Are Deceiving
Fish, Dolphins
& Sharks
Limpets,
Barnacles,
Crabs
What Characteristics Are Important & Which
Are Most Important?
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Traditional Classification
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Cladogram
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Evolutionary Classification
Key Concept
Biologists Now Group Organisms
Into Categories That Represent
Lines Of Evolutionary Descent,
Not Just Physical Similarities
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Evolutionary Classification
Is The Strategy of Grouping
Organisms Together Based On
Their Evolutionary History
Use of Evolutionary History is
referred to as Phylogeny
It Is Not Obvious or Easy
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Cladistic Analysis
Identifies and Considers Only Those
Characteristics Of Organisms That Are
Evolutionary Innovations
New Characteristics That Arise
As Lineages Evolve Over Time
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Cladistic Analysis
Derived Characteristics
Traits That Can Be Used To Figure Out Evolutionary Relationships
Appear In Recent Parts of a Lineage
But
Not In its Older Members
Used To Construct A Cladogram
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Cladogram
A Diagram That Shows The Evolutionary
Relationships Among a Group of
Organisms
Shows How One Lineage Branched From
Another In The Course of Evolution
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Similarities In DNA & RNA
1. Beyond Physical Characteristics
Are Similarities In DNA & RNA
2. Allows Comparison of Diverse
Organisms
3. Allows The Tracing of Genes Over
Millions of Years
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Similarities In DNA & RNA
Key Concept
The Genes of Many Organisms Show
Important Similarities At The
Molecular Level.
These Similarities Can Be Used As
Criteria To Help Determine
Classification
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Similarities In DNA & RNA
Myosin
Functional Protein Unit of Muscle Fibers
Found In Yeast (?)
Protein In Yeast Interacts With Other
Proteins To Allow Internal Yeast
Structures To Move
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Similarities In DNA & RNA
Has Cleared Up Classification Questions,
Which Two Are More Closely Related?
Storks, American Vultures, African Vultures
Panda’s
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Molecular Clocks
DNA Can Mark The Passage of Evolutionary Time
Mutations Occur At A Somewhat
Measurable Rate
If They Change The Phenotype, They Are
Subject To Natural Selection
If They Don’t Change The Phenotype, They
Accumulate In The DNA
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Molecular Clocks
The Degree of Difference Due To
Accumulated Mutations, Indicates
How Recently They Shared A
Common Ancestor
Different Genes “tick” At Different
Rates Allowing Comparison &
Validation
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Molecular Clocks
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