Species Diversity Today- Named and described 1.8 milliono Vertebrates: ~62,000o Insects: ~1,000,000o Other invertebrates: ~300,000o Mushrooms: ~32,000o Plants: ~320,000o Bacteria: ~9,850o Archaea: ~400- There are probably at least 10-100 million more species alive today (primarily eukaryote)- Some microbiologists estimate up to a billion prokaryotic speciesTaxonomic Hierarchy, Linnaean taxonomic classificationDomain Eukarya Kingdom Plantae Phylum Asteraceae Class Order Family Genus Helianthus Species Helianthus annuusWhy study diversity in an evolutionary context, i.e. “The Tree of Life”?- Basic info conveyed in phylogenetic tree- Phylogenies provide current context for many biological questions relevant for society- tolweb.org/tree/Domains: Bacteria & Archaea (prokaryotes); Protists, Plants, Fungi, & Animals (eukaryotes)Goal: organize diversity based on evolutionary historyChallenge: similar characters aren’t necessarily due to common history- Similar due to common ancestryo homology (focus of phylogenetics)- Similar due to independent evolution, not common ancestryo homoplasy (analogy)Are forearms in tetrapods homologous?- Two forelimbs & two hind limbs- Humerus, radius & ulna, carpals, metacarpals, phalanges- Evidence of common ancestry: DNA (how closely related they are), fossil record (indirect), ***bone structure***o Everyone in that group has same bone structureIs the capacity for flight a homology or homoplasy?- Homoplasy, aka convergent evolution- Evidence: bird and bat bone structure are not similar enough (part of answer), common ancestor(not all in that group can fly)Homoplasy examples- Placentals: flying squirrel, ground hog, anteater, mole, mouse- Marsupials: flying phalanger, wombat, anteater, mole, mouse- Ex: skin flap is just needed as adaptation; not related to evolutionCause of similarity for character of “being red”- Shared ancestral trait (homology): all 4 in group of interest have trait- Shared derived character homology): D & E have trait but came off same line- Convergent evolution (homoplasy): B & E have trait but came off different linesConstructing phylogenetic trees: hypothesis of evolutionary history of groups- Collect as much info as possible (morphology, biochemistry, genes of relevant groups)- Identify homologous traits (challenging)- Use shared derived homologous characters to construct timeline of character evolution phylogenetic treesLeopards lay amniotic eggs (similar to turtle)Nodes: each node or branching point represents a common ancestor splitting into 2 evolutionary lineagesSister taxa: closest relatives, those terminal taxa that share the most recent common ancestorClade= monophyletic group- Consists of most recent common ancestor and ALL descendantsParaphyletic: descendants of reptiles, minus birdsPolyphyletic: warm-blooded animals: mammals and birdsWe are undergoing a revolution in understanding evolutionary relationships - Figuring out the tree of life for many more of those 1.8 million named species- Tools and genetic characters will depend on the level of organization being