1. Chapter 25 ~ Phylogeny & Systematics

2. Phylogeny: the evolutionary history of a species Used to organize species by examing ancestors and descendantsUsed to organize species by examing ancestors and descendants Based on fossil, morphological and molecular homologiesBased on fossil, morphological and molecular homologies

3. Systematics: science of tracing evolutionary history of the speciesSystematics: science of tracing evolutionary history of the species The fossil record: the ordered array of fossils, within layers, or strata, of sedimentary rockThe fossil record: the ordered array of fossils, within layers, or strata, of sedimentary rock Paleontologists study fossilsPaleontologists study fossils

4. Taxonomy: identification of phylogeny of organisms Founded by Linnaeus ?Founded by Linnaeus ? Binomial classificationBinomial classification Taxon: unit of classificationTaxon: unit of classification –King Phillip Came Over For Great Spaghetti

5. Cladistics:groups organisms according to characteristics they share Gives us cladogramsGives us cladograms Branches of cladograms are called cladesBranches of cladograms are called clades Only as good as data used to make itOnly as good as data used to make it

6. The fossil record Sedimentary rock: rock formed from sand and mud that once settled on the bottom of seas, lakes, and marshesSedimentary rock: rock formed from sand and mud that once settled on the bottom of seas, lakes, and marshes Dating:Dating: 1- Relative~ geologic time scale; sequence of species1- Relative~ geologic time scale; sequence of species 2- Absolute~ radiometric dating; age using half-lives of radioactive isotopes2- Absolute~ radiometric dating; age using half-lives of radioactive isotopes

7. Biogeography: the study of the past and present distribution of species Pangaea-250 mya √ Permian extinctionPangaea-250 mya √ Permian extinction Geographic isolation-180 mya √ African/South American reptile fossil similarities √ Australian marsupialsGeographic isolation-180 mya √ African/South American reptile fossil similarities √ Australian marsupials

8. Mass extinction Permian (250 million years ago): 90% of marine animals; Pangea mergePermian (250 million years ago): 90% of marine animals; Pangea merge Cretaceous (65 million years ago): death of dinosaurs, 50% of marine species; low angle cometCretaceous (65 million years ago): death of dinosaurs, 50% of marine species; low angle comet

10. Phylogenetics The tracing of evolutionary relationships (phylogenetic tree)The tracing of evolutionary relationships (phylogenetic tree) LinnaeusLinnaeus BinomialBinomial Genus, specific epithetGenus, specific epithet Homo sapiensHomo sapiens Taxon (taxa)Taxon (taxa)

11. Constructing a Cladogram Sorting homology vs. analogy...Sorting homology vs. analogy... Homology: likenesses attributed to common ancestryHomology: likenesses attributed to common ancestry Analogy: likenesses attributed to similar ecological roles and natural selectionAnalogy: likenesses attributed to similar ecological roles and natural selection Convergent evolution: species from different evolutionary branches that resemble one another due to similar ecological rolesConvergent evolution: species from different evolutionary branches that resemble one another due to similar ecological roles

12. A Cladogram