Section 18-3: Building the Tree of Life

 In Linneaus’s time organisms were either plants or animals  Animals moved from place to place, used food  Plants green, got energy from sun, did not move  Does not reflect diversity  New data changed this idea, and it is still changing

 Kingdom Archaebacteria and Kingdom Eubacteria more genetically different from each other and from eukaryotes  Higher taxonomic group domain  Domain Bacteria (Kingdom Eubacteria)  Domain Archae (Kingdom Archaebacteria)  Domain Eukarya (Kingdoms “Protista” (not monophyletic), Fungi, Plantae, Animalia)

 Modern evolutionary classification constantly and rapidly changing  Tree of life shows current hypotheses

 All unicellular, prokaryotic  Kingdom Eubacteria (true bacteria)  Thick, rigid cell walls containing peptidoglycan  Ecologically diverse – some photosynthetic, some parasitic, some anaerobic, some aerobic

 Kingdom Archaebacteria  Unicellular, prokaryotic  Some live in extreme environments (some can only survive without oxygen)  No peptidoglycan in cell walls – membranes contain unusual lipids

 All organisms with nuclei  Kingdom Protista – Unicellular eukaryotes  “Catchall” kingdom  At least 5 clades  Only one group (brown algae) that is mutlticellular  Some photosynthetic, some heterotrophic  Some resemble fungi, plants, animals

 Kingdom Fungi  Heterotrophic, cells walls made of chitin  Most feed on dead/decaying organic matter  Extracellular digestion  Includes mushrooms (multicellular) and yeasts (unicellular)

 Kingdom Plantae  Multicellular, cells walls of cellulose, autotrophic  Chlorophyll  Nonmotile  Green algae, mosses, ferns, conifers, flowering plants

 Kingdom Animalia  Multicellular, heterotrophic  No cell wall  Most motile in some way