1. Classification of Organisms
Taxonomy & Phylogeny
Classification of Organisms

2. Classification What characters are suitable for classification
Systematics
Combination of taxonomy & phylogeny
Systematic approach to understanding evolutionary relationships among organisms
Fig. 10.CO

3. Hierarchical Classification System
Taxa
Major groupings or categories
Nested set of increasing inclusiveness
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

4. Cladistic Tree of Life
Fig

6. Wittiker’s 5 Kingdom Classification Scheme
Fig

9. Taxonomic Rules Binomial nomeclature Genus species Genus name is noun
species name is adjective
Higher taxonomic levels (families, orders, etc..) are also nouns

10. Taxonomy Relates to Phylogeny
Taxonomic characters allow phylogenetic grouping
Useful taxonomic characters
Morphological
Molecular (biochemical)
Chromosomal
Proteins
DNA
Homologies
Character similarities attributed to common ancestry

11. Using Taxonomic Characters to Construct Phylogenies
Ancestral character state
The form of the trait present in the most recent common ancestor of the groups being considered
Derived character state
The variant forms of the trait present in the members of the groups being considered
Polarity
Relationship of character trait state to ancestral state

12. Example of Polarity Determination
Study group
Amniotes – animals with amniotic membrane around developing embryo
Birds, Reptiles, Mammals
Character being studied
Dentition – teeth
Character states
Present
Absent
Question: Is dentition a derived or ancestral trait for amniotes?
Outgroup comparison
Phylogenetically close group, but non-amniote

13. Example of Polarity Determination
Amphibians &Fish
Mammals
Birds
Reptiles
no teeth
teeth
teeth
teeth
Non-Amniote
Amniote
Common Ancestor
teeth
Outgroup has teeth
therefore teeth are considered ancestral & be presumed to occur in most recent common ancestor of amniotes and non-amniotes
Teeth in amniotes is an ancestral character state
Loss of teeth in birds is a derived state

14. Cladograms Clade Synapomorphy Cladogram
Groups of organisms that share derived character states
Synapomorphy
Shared, derived character
Cladogram
Nested, hierarchical assembly and representation of clades

15. Phylogenetic Relationships Established by Comparison of Multiple Characters
Fig. 10.4

17. Cladograms vs Phylogenetic Trees
Lacks information
duration of lineages
Amounts of evolutionary change
Phylogenetic tree
Establishes extinct vs extant lineages
Indicates evolutionary timescale & degrees of change
Length of lines or numerical indications

18. Molecular Phylogeny Comparison of cytochrome c mutations Human
Fig. 10.5

19. Phylogenetic Groupings
Monophyletic
All descendents and most recent common ancestor
Paraphyletic
Leaves out some descendents from a recent common ancestor
Polyphyletic
Arbitrary groupings which do not include common ancestors
Fig. 10.6

23. Cladistics & Cladograms vs Traditional Taxonomy
Taxonomic groupings based solely on establishing monophyletic relationships
Cladograms establish monophyletic taxonomic levels
Traditional taxonomy
Common descent – phyletic relationship
Adaptive evolutionary change – ecological zones

24. Fig. 32.7

26. Fig. 10.9