1. Chapter 25: Phylogeny & Systematics
What is phylogeny?
Evolutionary history of a species
How can we trace phylogeny?
Relative dating
Based on layer fossil is found in
Older or younger
Absolute dating
Radiometric dating – C14, U238
Years ago alive

2. Figure 25.4 A gallery of fossil types
(a) Dinosaur bones being excavated from sandstone
(g) Tusks of a 23,000-year-old mammoth, frozen whole in Siberian ice
(e) Boy standing in a 150-million-year-old dinosaur track in Colorado
(d) Casts of ammonites, about 375 million years old
(f) Insects preserved whole in amber
(b) Petrified tree in Arizona, about 190 million years old
(c) Leaf fossil, about 40 million years old

3. Chapter 25: Phylogeny & Systematics
What is phylogeny?
How can we trace phylogeny?
Why aren’t there more fossils for “missing links” to extant organisms?
Conditions must be perfect for fossilization & discovery
May be present but not found
What is the difference between convergent & divergent evolution?
Convergent
Species from different evolutionary branches develop structures that
resemble one another
Shows analogy between species…..not homology from a
common ancestor
Divergent – gradual changes over time
5. What is taxonomy?
Identification & classification of species
D K P C O F G S

4. Figure 25.8 Hierarchical classification
Panthera
pardus
Felidae
Carnivora
Mammalia
Chordata
Animalia
Eukarya
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

5. Chapter 25: Phylogeny & Systematics
What is phylogeny?
How can we trace phylogeny?
Why aren’t there more fossils for “missing links” to extant organisms?
Conditions must be perfect for fossilization & discovery
May be present but not found
What is the difference between convergent & divergent evolution?
Convergent
Species from different evolutionary branches develop structures that
resemble one another
Shows analogy between species…..not homology from a
common ancestor
Divergent – gradual changes over time
5. What is taxonomy?
Identification & classification of species
D K P C O F G S
6. How have all organisms descended from a common ancestor on
the universal tree of life?

6. Figure 25.18 The universal tree of life
Bacteria
Eukarya
Archaea
4 Symbiosis of chloroplast ancestor with ancestor of green plants
3 Symbiosis of mitochondrial ancestor with ancestor of eukaryotes
2 Possible fusion of bacterium and archaean, yielding ancestor of eukaryotic cells
1 Last common ancestor of all living things 4 3 2 1
Billion years ago
Origin of life
Many phylogentic relationships have been shown through molecular biology
- DNA sequencing
- protein sequencing