1. Chapter 22 SYSTEMATICS – BIODIVERSITY + EVOLUTION

2. Taxonomy – naming, describing, and classifying organisms Naming: Worldwide system recognized by all scientists Binomial nomenclature -1 st developed by Carolus Linnaeus 2 part name: Genus + specific epithet = scientific name Genus name capitalized; species name not; both underlined or italics; both derived from Latin or Greek

3. Classifying – group organisms into meaningful categories Taxon – group (pl. taxa) – Linnaeus also established a hierarchy Kingdom, phylum, class, order, family, genus, species Currently we include a larger category above kingdom – domain (Dumb King Phillip came over for good spaghetti) We have three domains: Eubacteria (aka bacteria)prokaryotes Archaea Eukarya – plants, animals, protists, fungi New proposal – group organisms into clades – a set of organisms with a common ancestor (more on this later) Important – Figure 22-3 + Table 22-2, page 424

4. The three domains Common ancestor of all living organisms Domain Archaea Domain Eubacteria (bacteria) Domain Eukarya

5. The six-kingdom system of classification EubacteriaArchaebacteria ProtistaPlantae Protista Animalia Fungi Common ancestor of all living organisms Common ancestor of all eukaryotes

6. Phylogeny – using systematics to describe the evolutionary history of life on Earth Based on available data – changed to adjust to new information Homology – helpful similarities Structures that are found in 2 or more groups that share a recent common ancestor Example: wing of a bat and a bird Homoplasy – not helpful similarities Superficial similarity due to convergent evolution rather than descent from a common ancestor Example: wing of a bird and a butterfly The difference between these is not always easy to see

7. So, we want to make an evolutionary ‘family tree’… The branches use two set of features: Shared ancestral characters – plesiomorphic characters Found in all descendants from a particular ancestor (everyone on that ‘branch’) Example: vertebral column – all vertebrates have this Shared derived characters – synapomorphic characters Found in 2 or more taxa with a recent common ancestor (smaller ‘branches’) Example: middle ear bones  found in all mammals; identifies the branch between reptiles and mammals

8. Can we use molecular information? Of course! Molecular systematics compares macromolecules, especially DNA, RNA, and amino acid sequences Molecular clocks can be used to establish how long 2 groups have been evolving separately from each other (assuming a constant rate of change) rRNA sequences – have been studied extensively and used as molecular clocks

9. Three kinds of taxonomic groupings: 1.Monophyletic taxon Ancestral species and all its descendants (see figure 22-6a p 428) Example: mammals 2.Paraphyletic taxon Common ancestor and some but not all descendants Not used in cladistics Example: reptiles – because birds are in a separate taxon despite the fact that they share a common ancestor with reptiles 3.Polyphyletic group ‘accidentally’ put organisms in groups even though they do not share a common ancestor, perhaps because of homoplastic features Example: the Protista Kingdom This is avoided in cladistics because it does not show evolutionary relationships

10. Evolutionary relationships Taxon III Common ancestor Common ancestor to groups 4, 5, and 6 Common ancestor to groups 5 and 6 Common ancestor to all groups Common ancestor to all groups except 1 Common ancestor to groups 2 and 3 A B D E C 123456 Taxon I"Taxon II"

11. Two approaches to the classification of reptiles birds, and mammals. MammalsLizardsSnakes Crocodiles Dinosaurs Common ancestor Birds Reptiles

12. Two approaches to the classification of reptiles birds, and mammals. A B D E C MammalsLizards SnakesCrocodiles Dinosaurs Common ancestor Birds Reptiles