Taxonomy Taxonomy – field of classifying organisms & assigning each organism a universally accepted name Binomial nomenclature – 2-word naming system by Carolus Linnaeus Always in italics, first word is capitalized, second word is lowercased. Genus species Example: Homo sapien (human) Ursus arctos Ursus maritimus

Taxonomy All life is classified into 3 domains based on common characteristics: Eubacteria: prokaryotes; “true” bacteria; Ex. Pathogens Archaebacteria: prokaryotes; live in extreme environments Eukarya: eukaryotes; Ex. plants, animals, fungi, protists

Taxonomy Each domain can be broken down into more and more specific levels based on shared characteristics: Kingdom Phylum Class Order Family Genus Species Thus in binomial nomenclature, we name organisms based on their two most specific names Pause and Play: Great Crash Course video if you want to pause in notes here and show it: https://www.youtube.com/watch?v=F38BmgPcZ_I

Evolutionary History Phylogeny - evolutionary history of a species or a group of related species. Phylogenetic Tree – diagram that biologists use to predict the evolutionary relationships of organisms Organized based on evidence as well as taxonomy Constructed to make the simplest relationships possible

Phylogenetic Trees Classifies organisms into major taxa (groups) based on evolutionary relationships. Classifies species in the order in which they descended from a common ancestor using physical characteristics. Trees can show order of species divergence from the common ancestor and some even more specifically show time of divergence.

Phylogenetic Trees From a phylogenetic tree we can learn: Which groups are most closely related Which groups are least closely related Which group diverged first (longest ago)

How to Read them Speciation - branching of a family tree Extinction - loss of one of the branches. Start from the “trunk” – this always represents a common ancestor that all organisms on the tree evolved from Each node represents a more recent common ancestor

How NOT to Read them They do not show that A  B  C  D Ex. Bacteria  Amoeba  Insect  Trout  Human and Bird is NOT correct They do not show A > B > C > D Ex. Humans are not greater than trout which is not greater than insects….etc.

Example What do you know from this phylogenetic tree?