Chapter 25 Essential Questions LO 1.13 The student is able to construct and/or justify mathematical models, diagrams or simulations that represent processes of biological evolution. LO 1.17 The student is able to pose scientific questions about a group of organisms whose relatedness is described by a phylogenetic tree or cladogram in order to (1) identify shared characteristics, (2) make inferences about the evolutionary history of the group, and (3) identify character data that could extend or improve the phylogenetic tree. LO 1.18 The student is able to evaluate evidence provided by a data set in conjunction with a phylogenetic tree or a simple cladogram to determine evolutionary history and speciation. LO 1.19 The student is able create a phylogenetic tree or simple cladogram that correctly represents evolutionary history and speciation from a provided data set. LO 1.26 The student is able to evaluate given data sets that illustrate evolution as an ongoing process.

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 – p 517 Radiometric dating – C14, U238 Years ago alive Example: How long ago was fossilized organism alive? Given: 1/16 isotope remaining & isotope has t½ = 4000 yrs Answer 1/16 = 4 half lives 4 X 4000 yrs = 16,000 yrs ago it was 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

Students Place lab notebooks on shelf LL mid-point check – Monday How many watched the H-W video from Bozeman Science? Phones in bin…muted or off….please & thank you!! Any LL questions now? 

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…no common ancestor 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. What is a cladogram? Diagram that shows shared characteristics

Figure 25.11 Constructing a cladogram

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. What is a cladogram? Diagram that shows shared characteristics Groups can either be monophyletic, paraphyletic or polyphyletic

Monophyletic – one group coming from a single common ancestor Paraphyletic – a grouping with one but not all ancestors derived from it Polyphyletic – a grouping of several species that lack a common ancestor

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? What is taxonomy? What is a cladogram? How can molecular clocks help to track evolutionary time? Assumes that some genes & parts of the genome appear to evolve at a constant rate We can then compare genomic changes to known evolutionary branch points in the fossil record Using a molecular clock, researchers concluded that HIV-M first infected humans in the 1930s 8. 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