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

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

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

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

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?

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