1. ORGANIZING DIVERSITY: Taxonomy and Systematics
Nomenclature
Taxonomic Hierarchy
Phylogenies

2. Taxonomy/systematics: naming and classifying
Phylogeny: determines evolutionary history/relationships of organisms

3. Taxonomy and Origin of Classification
Carolus Linnaeus (mid-1700’s) created classifications based on resemblances.
Two main features of Linnaean system persist:
Binomial nomenclature
Hierarchical classification

4. Binomial Nomenclature
Genus Name + specific epithet
Capitalized & italicized
Italicized, but NOT capitalized
Unique within genus
Sequoiadendron giganteum
It takes both parts to make the species name

5. Binomial Nomenclature
Salvia apiana
Salvia mellifera
Artemesia californica

6. Hierarchical Classification
Figure 26.3
Cell
division
error
Hierarchical Classification
group = taxon (taxa)
Species:
Panthera pardus
Genus:
Panthera
Family:
Felidae
Order:
Carnivora
Address Analogy:
m.Covill
Biology Dept
11110 Alondra Blvd
Norwalk, CA
USA
Class:
Mammalia
Figure 26.3 Linnaean classification
Phylum:
Chordata
Kingdom:
Animalia
Domain:
Bacteria
Domain:
Archaea
Domain:
Eukarya

7. Organizing life into groups (taxa)
compare morphology, physiology, biochemistry, embryology, and DNA sequences when grouping organisms
Linnaean system predates evolutionary theory
Systematics and phylogenies
Linnaean classification and phylogeny can differ from each other
Systematists have proposed a classification system that would recognize only groups that include a common ancestor and all its descendants
Ongoing attempts and proposals to reconcile the original Linnaean classification and modern phylogenies

8. Linking Classification and Phylogeny
The evolutionary history of a group of organisms can be represented in a branching phylogenetic tree
Created using:
Structural (morphological) characteristics
Developmental characteristics
Biochemical characteristics
Genetics/DNA sequences

9. divergent, speciation events Monitor lizard
Figure 26.2
Geckos
ANCESTRAL
LIZARD
(with limbs)
No limbs
Snakes
Iguanas
divergent, speciation events
Monitor lizard
Figure 26.2 Convergent evolution of limbless bodies
Eastern glass lizard
No limbs

10. A phylogenetic tree represents a hypothesis about evolutionary relationships
Each branch point represents the divergence of two species
Tree branches can be rotated around a branch point without changing the evolutionary relationships
Sister taxa are groups that share an immediate common ancestor

11. where lineages diverge Taxon A
Figure 26.5
Branch point:
where lineages diverge
Taxon A 3
Taxon B
Sister
taxa 4
Taxon C 2
Taxon D
Taxon E 5
ANCESTRAL
LINEAGE 1
Taxon F
Figure 26.5 How to read a phylogenetic tree
Basal
taxon
Taxon G
This branch point
represents the
common ancestor of
taxa A–G.
This branch point forms
a polytomy: an
unresolved pattern of
divergence.

12. Phylogeny + classification
Figure 26.4
Order
Family
Genus
Species
Felidae
Panthera
pardus
(leopard)
Panthera
Taxidea
taxus
(American
badger)
Taxidea
Carnivora
Mustelidae
Lutra lutra
(European
otter)
Lutra 1
Figure 26.4 The connection between classification and phylogeny
Canis
latrans
(coyote)
Canidae
Canis 2
Canis
lupus
(gray wolf)
Phylogeny + classification

13. Creating Phylogenies Using Cladistics
Cladistics groups organisms by common descent
A clade is a group of species that includes an ancestral species and all its descendants
Clades can be nested in larger clades, but not all groupings of organisms qualify as clades
Not all taxa are clades
Represents an inconsistency between phylogeny and Linnaean classifications

14. TAXA (outgroup) Lancelet Lamprey Leopard Bass Frog Turtle Four walking
Figure 26.12a
TAXA
(outgroup)
Lancelet
Lamprey
Leopard
Bass
Frog
Turtle
Four walking
legs 1 1 1
Hair 1
Amnion
CHARACTERS 1 1
Figure 26.12a Constructing a phylogenetic tree (part 1: character table)
Vertebral
column 1 1 1 1 1
Hinged jaws 1 1 1 1
(a)
Character table

15. TAXA (outgroup) Lancelet Lamprey Leopard Bass Frog Turtle Vertebral
Figure 26.12a
TAXA
(outgroup)
Lancelet
Lamprey
Leopard
Bass
Frog
Turtle
Vertebral
column
(backbone) 1 1 1 1 1
Hinged jaws 1 1 1 1
Four walking
legs
CHARACTERS 1 1 1
Figure 26.12a Constructing a phylogenetic tree (part 1: character table)
Amnion 1 1
Hair 1
(a)
Character table

16. Lancelet (outgroup) Lamprey Bass Vertebral column Frog Hinged jaws
Figure 26.12b
Lancelet
(outgroup)
Lamprey
Bass
Vertebral
column
Frog
Hinged jaws
Turtle
Figure 26.12b Constructing a phylogenetic tree (part 2: phylogenetic tree)
Four walking legs
Amnion
Leopard
Hair
(b)
Phylogenetic tree

17. Figure 26.12
TAXA
Lancelet
(outgroup)
(outgroup)
Lancelet
Lamprey
Leopard
Lamprey
Bass
Frog
Turtle
Vertebral
column
(backbone) 1 1 1 1 1
Bass
Vertebral
column
Hinged jaws 1 1 1 1
Frog
Hinged jaws
Four walking
legs
CHARACTERS 1 1 1
Turtle
Four walking legs
Amnion 1 1
Figure Constructing a phylogenetic tree
Amnion
Hair 1
Leopard
Hair
(a)
Character table
(b)
Phylogenetic tree

18. Shared Ancestral and Shared Derived Characters
In comparison with its ancestor, an organism has both shared and different characteristics
A shared ancestral character is a character that originated in an ancestor of the taxon
Symplesiomorphy (trait on own w/o ref to shared is plesiomorphy)
A shared derived character is an evolutionary novelty unique to a particular clade
A character can be both ancestral and derived, depending on the context

19. Morphological and Molecular Homologies
Phenotypic and genetic similarities due to shared ancestry are called homologies
When constructing a phylogeny, systematists need to distinguish whether a similarity is the result of homology or analogy
Homology is similarity due to shared ancestry
Shared derived characteristics
Analogy is similarity due to convergent evolution homoplasies = analogous structure

20. Monophyletic group (clade) (b) Paraphyletic group (c)
Figure 26.10
(a)
Monophyletic group (clade)
(b)
Paraphyletic group
(c)
Polyphyletic group A A A 1 B
Group I B B
Group III C C C D D 3 D E E
Group II E F 2 F F
Figure Monophyletic, paraphyletic, and polyphyletic groups G G G

21. Clade= monophyletic = consists of the ancestor species and all its descendants
paraphyletic = consists of an ancestral species and some, but not all, of the descendants
polyphyletic = includes distantly related species but does not include their most recent common ancestor

22. Paraphyletic group Common ancestor of even-toed ungulates
Figure 26.11
Paraphyletic group
Common
ancestor of
even-toed
ungulates
Other even-toed
ungulates
Hippopotamuses
Cetaceans
Seals
Figure Examples of a paraphyletic and a polyphyletic group
Bears
Other
carnivores
Polyphyletic group

23. Phylogenetic Tree Variations s with Proportional Branch Lengths
branch lengths reflect the number of genetic changes that have taken place in lineage
branch length can represent chronological time

24. Maximum Parsimony and Maximum Likelihood
Systematists can never be sure of finding the best tree in a large data set
They narrow possibilities by applying the principles of maximum parsimony and maximum likelihood
Maximum parsimony assumes that the tree that requires the fewest evolutionary events (appearances of shared derived characters) is the most likely
The principle of maximum likelihood states that, given certain rules about how DNA changes over time, a tree can be found that reflects the most likely sequence of evolutionary events
Both use computer programs to determine the most parsimonious and likely

25. Concept 26.4: An organism’s evolutionary history is documented in its genome
Comparing nucleic acids or other molecules to infer relatedness is a valuable approach for tracing organisms’ evolutionary history
DNA that codes for rRNA changes relatively slowly and is useful for investigating branching points hundreds of millions of years ago
mtDNA evolves rapidly and can be used to explore recent evolutionary events

26. Cell division error Euglenozoans Forams Diatoms Ciliates Red algae
Figure 26.21
Cell
division
error
Euglenozoans
Forams
Diatoms
Ciliates
Red algae
Domain Eukarya
Green algae
Land plants
Amoebas
Fungi
Animals
Nanoarchaeotes
Methanogens
Domain
Archaea
COMMON
ANCESTOR
OF ALL LIFE
Thermophiles
Figure The three domains of life
Proteobacteria
(Mitochondria)*
Chlamydias
Spirochetes
Domain Bacteria
Gram-positive
bacteria
Cyanobacteria
(Chloroplasts)*