Chapter 18 Classification 18 1 Finding Order in

Chapter 18 Classification

18. 1 Finding Order in Diversity • Systematics – science of naming and grouping organisms • Binomial Nomenclature – two word naming system started by Carolus Linnaeus to describe and name each species • Each species is give a two part name: First part = Genus Second part = species • Both are either underlined or italicized: ex: Genus species or Genus species • Names are in Latin so they are universal • Ex. Human = Homo sapiens • System expanded to include 7 taxa • • Kingdom Phylum Class Order Family Genus Species

18. 2 Modern Evolutionary Classification • Evolutionary Classification – the study of evolutionary relationships among organisms; called PHYLOGENY • Phylogeny- the study of how living and extinct organisms are related to one another • Classify/group organisms into categories that reflect lines of evolutionary descent rather than overall similarities and differences • Place organisms into higher taxa based on relatedness • Clade – a group of species that includes a single common ancestor (living and extinct) • Use Derived Characteristics to assign species to clades • A trait that arose in the most recent common ancestor of a particular lineage and was passed along to its descendants • Ex: Felidae clade = retractable claws

18. 2 Modern Evolutionary Classification Cladograms – diagrams that show species and higher taxa are related to each other • Shows evolutionary lines, or lineages, branched off from a common ancestor • Places where the lineage spits is called a fork or node • Nodes represents the point where new lineages last shared a common ancestor • The root (at the bottom) represents the ancestor shared by all of the organism on the cladogram • Relies of derived characters • Building a Cladogram constructing a cladogram ws Based on the cladogram, are amphibians more closely related to humans or to ray-finned fish?

18. 2 Modern Evolutionary Classification • What are the derived characters in the cladogram and which groups have those characters?

18. 2 Modern Evolutionary Classification • DNA is Classification • All organisms have DNA, which can be compared in different species. • The more derived genetic characteristics two species share, the more recently the species shared a common ancestor and the more closely related they are.

18. 3 Building the Tree of Life • The tree of life shows current hypotheses regarding evolutionary relationships among taxa within the three domains of life • Current 3 Domain and 6 Kingdom System

18. 3 Building the Tree of Life

DOMAINS OF LIFE • 3 Domains of Life • Archaea (prokaryotic) • Bacteria (prokaryotic) • Eukarya (eukaryotic)

DOMAIN BACTERIA Prokaryotic Unicellular Cell walls contain peptidoglycan Ecologically diverse ranging from freeliving soil organisms to deadly parasites. • Some autotrophic, some heterotrophic • Some need oxygen to survive (aerobic), some are killed by oxygen (anaerobic) • Only one kingdom within this domain: Kingdom Eubacteria • •

DOMAIN ARCHAEA Prokaryotic Unicellular Cell walls do NOT contain peptidoglycan Live in very harsh environments Some autotrophic, some heterotrophic Some need oxygen to survive (aerobic), some are killed by oxygen (anaerobic) • Only one kingdom within this domain: Kingdom Archaebacteria • • •

IMPORTANCE OF PROKARYOTES 1) Ecological Importance: Essential in maintaining every aspect of the ecological balance of the living world • Decomposers – recycling raw materials to the environment, essential to sewage treatment & production of purified water • Producers – cyanobacteria are among the most plentiful photosynthetic organisms in the world & many food chains are dependent upon them • Nitrogen Fixers – converting nitrogen gas into useable forms 2) Human Uses • Food – yogurt, other dairy products • Medicine – making drugs for medical treatments 3) Disease – some bacteria can cause disease by destroying living cells or by releasing chemicals that upset homeostasis • EX’s/ Lyme disease, Tetanus, Tuberculosis, Strep Throat • Controlled by sterilization, disinfectants • Prevented by vaccines

DOMAIN EUKARYA • All Eukaryotes: contain a nucleus & other membrane-bound organelles • Four Kingdoms • • Protista (protists) Fungi Plantae Animalia

PROTISTS • Unicellular, Colonial, or Multicellular • Photosynthetic or Heterotrophic • Catchall kingdom – group of eukaryotes that did not fit into plants, animal or fungus kingdom

ECOLOGICAL IMPORTANCE OF PROTISTS • Autotrophic Protists – photosynthetic protists at the base of the food chain makes much of the diversity of aquatic life possible • EX/ Algae • Heterotrophic Protists – some heterotrophic protists engulf and digest their food, while others live by absorbing molecules from the environment. • EX/ Paramecium, amoeba • Symbiotic Protists • Mutualistic – algae help health of coral reefs, Trichonympha live in guts of termites, helping them to digest cellulose • Parasitic – can cause intestinal disease, African Sleeping Sickness, & Malaria Red blood cell

FUNGI • Heterotrophic – feed on dead or decaying organic matter (absorb) • Secrete digestive enzymes into their food source, then absorb nutrients though their cell walls • Cell walls made of chitin • Unicellular (yeasts) or Multicellular (mushrooms)

ECOLOGICAL IMPORTANCE OF FUNGI • Decomposers – many species of fungi help ecosystems maintain homeostasis by breaking down dead organisms and recycling essential elements and nutrients. • Parasites – parasitic fungi can cause serious diseases in plants and animals • EX/smuts and rusts in plants • Athlete’s foot & ringworm • Symbiotic Fungi: • Lichens – mutualistic association between a fungus and a photosynthetic partner (algae or cyanobacteria). Are often the first organisms to enter barren environments and help in early stages of soil formation. • Michorrhizae – mutualistic association between a fungus and a plant root. Estimates that 80 -90% of all plant species have this sort of relationship. Fungus collects water and minerals, bringing them to the root, plant supplies the fungi with the products of photosynthesis (sugars).

PLANTS • Multicellular • Cell walls with cellulose • Autotrophic • Have chloroplasts

ANIMALS • Multicellular • Heterotrophic • No cell walls • Most can move