Classification Chapter 18 2006-2007

What is Classification? System to organize ALL living things into groups with biological meaning. Taxonomy: The study of classification.

Assigning a Name Problem: Common names can vary among languages. Common name is misleading. Descriptions are too long to be a name. ex: Mountain Lion or Puma or Cougar ex: Starfish, dragonfly ex:“Oak with deeply divided leaves that have no hairs on their undersides and no teeth around their edges.” Solution: Latinized and Greek words are commonly used to avoid any language issues. Reduce the number of words to a two part name.

Carolus Linnaeus Homo sapiens The Linnean system where each species has a 2 part (scientific) name: BIONOMIAL NOMENCLATURE genus Species (Genus is 1st word, species is 2nd) Homo sapiens means “wise man” perhaps in a show of hope & optimism

Genus groupings Classify organisms into broader groups Species that are closely related are grouped into the same genus Leopard Panthera pardus African lion Panthera leo Tiger Panthera tigris

Classification System Linnaeus’ hierarchical system: Kingdom general Phylum Class Order Family Genus Species specific Taxons (Kings play chess on fine gold squares)

So…, classification sequence is now: Kingdoms and Domains Modern groups are six kingdoms: Eubacteria, Archaebacteria, Protista, Fungi, Plantae, Animalia Domains – newest, largest inclusive category developed from comparing r-RNA subunits. Bacteria, Archaea, Eukarya So…, classification sequence is now: D, K, P, C, O, F, G, S

Cladogram comparing Domains

Bacteria & Archaebacteria Eukaryote Prokaryote Classification 6 Kingdom system Prokaryotes No separate organelles in their cells Bacteria Archaebacteria Eukaryotes Separate organelles in their cells Protists Plants Fungi Animals Bacteria & Archaebacteria

Classification of Living Things Figure 18-12 Key Characteristics of Kingdoms and Domains Taxon Characteristics Section 18-3 Classification of Living Things DOMAIN KINGDOM CELL TYPE CELL STRUCTURES NUMBER OF CELLS MODE OF NUTRITION EXAMPLES Bacteria Eubacteria Prokaryote Cell walls with peptidoglycan Unicellular Autotroph or heterotroph Streptococcus, Escherichia coli Archaea Archaebacteria Prokaryote Cell walls without peptidoglycan Unicellular Autotroph or heterotroph Methanogens, halophiles Protista Eukaryote Cell walls of cellulose in some; some have chloroplasts Most unicellular; some colonial; some multicellular Autotroph or heterotroph Amoeba, Paramecium, slime molds, giant kelp Fungi Eukaryote Cell walls of chitin Most multicellular; some unicellular Heterotroph Mushrooms, yeasts Eukarya Plantae Eukaryote Cell walls of cellulose; chloroplasts Multicellular Autotroph Mosses, ferns, flowering plants Animalia Eukaryote No cell walls or chloroplasts Multicellular Heterotroph Sponges, worms, insects, fishes, mammals

Organizing systems Making sense out of the differences Eastern gray squirrel Sciurus carolinensis

Organizing the world of organsims The Tree of Life organize creatures by structure & function how they are built how they live organize them into groups of closely related creatures

Modern Classification Just using appearance is not enough. New system uses: 1. Fossils 2. Dissections/comparative anatomy 3. Molecular similarities/DNA/enzymes 4. Evolutionary similarities or developmental milestones Ex: amniotic sac, jaws, endothermic

Cladistics Classifying organisms according to the order that they diverged from a common ancestor. Ancestral characters – found in all groups Derived characters – found in some groups ex: backbone is an ancestral trait found in all birds and mammals ex: hair is a derived trait found in only mammals

Vertebrate Cladogram What are the Derived Traits in this cladogram? What could the ancestral trait be? Which organisms share the trait of claws/nails? Which organism doesn’t have any of the traits? Which organisms are more closely related? Perch and pigeon Pigeon and chimp