Download Unit 7 Notes 4 Classification and Phylogenetics

Unit 8 Part 5
Classification and Phylogenetics
Taxonomy
• The discipline of
classifying organisms and
assigning each organism a
universal name.
• Why classify?
– Continuity among
scientists
– To construct logical
groupings/organizations
Linnaeus’ System of Naming
• Carolus Linnaeus (1700’s)
• Swedish botanist
• Binomial nomenclature
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2-part naming system
Latin, written in italics
First word (capitalized) is the genus
Second word (lowercased) is the species
Example:
Ursus maritimus (polar bear)
Linnaeus’ System of Classification
• Hierarchical system of classification
• Seven levels
• From smallest (most specific) to largest (most broad or
inclusive), these levels are:
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Species
Genus
Family
Order
Class
Phylum
Kingdom
• Today we also have an even more broad level:
Domains
The Tree of
Life
The Tree of Life
• Three Domains—Most inclusive categories:
– Archaea
• Kingdom Archeabacteria
• Prokaryotes, unicellular
• Example: halophiles  live in extreme environments
– Bacteria
• Kingdom Eubacteria (“new”)
• Prokaryotes, unicellular
• Example: E. coli
– Eukarya
• Kingdoms: Protista, Fungi, Plantae, and Animalia
• Eukaryotes, both unicellular and multicellular
• Example: Mushrooms, Paramecium, Ferns, Humans
Bacteria
Archaea
Eukarya
Phylogenetics
• The study of the evolutionary relationships among
organisms –evolutionary classification.
• Darwin’s ideas about descent with modification have
rise to this study.
• Several types of data are used to examine these
relationships:
– Molecular data (DNA, genes)
– Anatomy and Physiology
– Fossil records
• We organize this data into cladograms…
Cladistic Analysis
• A cladogram is a diagram that shows the
evolutionary relationships among a group of
organisms.
• Allow us to:
– Identify characteristics that were important to the
organisms’ evolutionary history.
– Compare changes over time.
• We focus on characteristics (adaptations) that
have evolutionary significance
Derived Characters
• Evolutionary significance
• Show up in more recently evolved species but
not in their ancestors.
• Illustrate how the more recent species have
evolved adaptations in response to their
environments.
Derived characters
Understanding Cladograms
Cladogram Terms
Base = Common Ancestor
Ends= Individual organisms or groups.
Moving toward ends = More recent
evolution
Moving toward base = Going back in time
Branches:
The CLOSER organisms’ branches are the
MORE SIMILAR their derived characters are.
The FURTHER away organisms’ branches are
the MORE DIFFERENT their characteristics
are.
Review our Understanding
• Video  Crash Course: Taxonomy
Quick Lab: Constructing a Cladogram
1. Start: Identify the organism in the table that is
least closely related to the others.
2. Then: Identify organisms which are more
closely related.
3. Now: Draw and Label your cladogram.
Organism
Derived Character
BACKBONE
LEGS
HAIR
Earthworm
Absent
Absent
Absent
Trout
Present
Absent
Absent
Lizard
Present
Present
Absent
Human
Present
Present
Present