1. SYSTEMATICS
The reconstruction and study of evolutionary relationships

2. Taxonomy Two main objectives:
to sort out organisms into species
to classify species into higher taxonomic levels
Species that appear to be closely related are grouped into the same genus.
the leopard, Panthera pardus, belongs to a genus that includes the African lion (Panthera leo) and the tiger (Panthera tigris).
Taxon = a named taxonomic unit at any level; (taxa = plural)
ex: Mammalia is a taxon at the Class level

3. TAXONOMY taxonomic system developed by Linnaeus in the 18th century
binomial = Genus species
classification system
Domain Eukarya
Kingdom Animalia
Phylum Chordata
Class Mammalia
Order Primates
Family Hominidae
Genus Homo
species sapiens

4. Did King Phillip Come Over For Great Sex?
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Did
King
Phillip
Come
Over
For
Great
Sex?
Domain
Eukarya
Kingdom
Animalia
Phylum
Chordata
Subphylum
Vertebrata
Class
Mammalia
Order
Rodentia
Family
Sciuridae
Genus
Sciurus
Species
Sciurus
carolinensis
Sciurus
carolinensis

5. Limitations of the Linnean System
Many hierarchies are being re-examined based on the results of molecular analysis
-Linnaean taxonomy does not take into account evolutionary relationships
-The phylogenetic and systematic revolution is underway

6. PHYLOGENY Hypothesis of the evolutionary history of a group
represented by pictures: phylogenetic trees
time goes from the bottom up
read from bottom up, NOT LEFT TO RIGHT
branch “length” = the number of changes

7. Fig. 23.1 a. b. Variations of a Cladogram Gibbon Human Chimp Gorilla
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Variations of a Cladogram
Gibbon
Human
Chimp
Gorilla
Orangutan
Gibbon
Orangutan
Gorilla
Human
Chimp 1 1 2 2 3
Chimp 3 1
Version 1
Version 2 2
Human 3
Gorilla
Orangutan
Gibbon
Version 3 a. b.
Reproduced by kind permission of the Syndics of Cambridge University Library, Darwin’s Notebook ‘B’, ‘Tree of Life’ Sketch, p. 36 from DAR.121 D312

11. Phylogenies depict evolutionary relationships

12. Phylogenetic trees reflect the hierarchical classification of taxonomic groups nested within more inclusive groups.
Fig. 25.8
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

13. Approaches to Constructing Phylogenies
Cladistics
uses shared derived characteristics (synapomorphies) to classify organisms
Not shared ancestral characteristics (symplesiomorphies)
not overall similarity
Because evolution is not steady paced, not unidirectional, may be convergent

14. Cladistics Examples of ancestral versus derived characters
Presence of hair is a synapomorphy (shared derived feature) of mammals
Presence of lungs in mammals is a symplesiomorphy (an ancestral feature); also present in amphibians and reptiles

15. Building Cladograms a. b. Traits: Organism Jaws Lungs Amniotic
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Traits:
Organism
Jaws
Lungs
Amniotic
Membrane
Hair
No Tail
Bipedal
Lamprey
Shark
Salamander
Lizard
Tiger
Gorilla
Human
Lamprey
Shark 1
Bipedal
Salamander 1 1
Tail loss
Lizard 1 1 1
Hair
Tiger 1 1 1 1
Amniotic
membrane
Lungs
Gorilla 1 1 1 1 1
Jaws
Human 1 1 1 1 1 1 a. b.

16. Can also use molecular data
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
DNA Sequence
Outgroup
Species B
Species D
Species A
Species C
Site 1 2 3 4 5 6 7 8 9 10
Species A G C A T A G G C G T
8:T C
Species B A C A G C C G C A T
4:T G
10:T G
1:A G
8:T C
5:C A
Species C G C A T A G G T G T
6:C G
Homoplastic
evolutionary
changes
9:A G
Species D A C A T C G G T G G
2:T C
Homologous
evolutionary
changes
Outgroup A T A T C C G T A T

17. PHYLOGENY systematists prefer monophyletic taxa
a single ancestor gave rise to all species in that taxon and to no species in any other taxa

18. Systematics and Classification
Monophyletic Group

19. Systematics and Classification
Paraphyletic Group

20. Systematics and Classification
Polyphyletic Group

21. Systematics and Classification
Old plant classification system

22. Systematics and Classification
New plant classification system

23. Evidence used to reconstruct phylogenies
Comparative anatomy, morphology, embryology, etc.
problems of homology vs homoplasy (analogy)
homology = likeness due to common ancestry
homoplasy or analogy = likeness due to convergent evolution

27. Fig. 23.9 SCIENTIFIC THINKING Question:
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SCIENTIFIC THINKING
Question:
How many times have saber teeth evolved in mammals?
Hypothesis: Saber teeth are homologous and have only evolved once in mammals (or, conversely, saber teeth are convergent and have evolved multiple times in mammals).
Phylogenic Analysis: Examine the distribution of saber teeth on a phylogeny of mammals, and use parsimony to infer the
history of saber tooth evolution (note that not all branches within marsupials and placentals are shown on the phylogeny).
Phylogeny of Mammals
Phylogeny of Carnivores
Saber-toothed
marsupial
weasels, canids,
Bears, seals,
and raccoons
Saber-toothed
cat
Saber-toothed
nimravid
Saber-toothed
nimravid
Carnivores
Mongooses
Civets
Hyenas
Felines
Marsupials
Placentals
Nimravids
Monotremes
Carnivores
Result: Saber teeth have evolved at least three times in mammals: once within marsupials, once in felines, and at least once in a group of now-extinct cat-like carnivores alled nimravids.
Interpretation: Note that it is possible that saber teeth evolved twice in nimravids, but another possibility that requires the same number of
evolutionary changes (and thus is equally parsimonious) is that saber teeth evolved only once in the ancestor of nimravids and then
were subsequently lost in one group of nimravids.
(Note that for clarity, not all branches within marsupials and placentals are shown in this illustration.)

28. Evidence used to reconstruct phylogenies
Protein comparisons
DNA comparisons
DNA-DNA hybridization, restriction mapping, DNA sequencing

29. Can Have Homoplastic Molecular Data
A Cladogram: DNA

30. Character Mapping
Once you have a phylogeny you can trace the evolution of characters or traits in that group
use the rules of parsimony
the simplest is the best

31. Parental Care
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. b.
a: Image #5789, photo by D. Finnin/American Museum of Natural History; b: © Roger De La Harpe/Animals Animals

33. Parsimony and Homoplasy

34. Classification System

36. Six Supergroups Within Eukarya
Eubacteria
Archaea
Chromalveolates
Rhizaria
Archaeplastida
Excavata
Amoebozoa
Opisthokonta
Excavata (organisms lacking typical mitochondria)
Chromalveolata (organisms with chloroplasts obtained through secondary endosymbiosis)
Archaeplastida (organisms with chloroplasts for photosynthesis)
Rhizaria (organisms with slender pseudopods used for movement)
Amoebozoans (organisms with blunt pseudopods used for movement)
Opisthokonts (fungi, animal ancestors, and animals)

38. Grouping Organisms Carl Woese proposed a six-kingdom system
Prokaryotes
Eukaryotes

39. KINGDOMS Monera = Archaebacteria & Eubacteria prokaryotic Protista
eukaryotic
Plantae
eukaryotic, multicellular, autotrophic, cell walls
Fungi
eukaryotic, multicellular, heterotrophic, cell walls
Animalia
eukaryotic, multicellular, heterotrophic, no cell walls