Building the Tree of Life (Ch 18.3) Unit 5: Evolution

Changing Ideas About Kingdoms Linnaeus was able to differentiate between animals and plants, but that does not reflect the full diversity of life Five Kingdoms Single-celled eukaryotic organisms (Protista) All prokaryotes that lack nuclei, mitochondria, and chloroplasts Yeasts and molds were placed in their own kingdom (Fungi) Kingdoms: Monera, Protista, Fungi, Plants, Animals

Changing Ideas About Kingdoms Six Kingdoms Bacteria needed to be split into two categories because of their genetic makeup (Monera → Archaebacteria and Eubacteria) Kingdoms: Archaebacteria, Eubacteria, Protista, Fungi, Animalia, Plantae Three Domains Domain: larger more inclusive category than a kingdom Domains: Bacteria (Eubacteria), Archaea (Archaebacteria), Eukarya (Fungi, Animalia, Plantae, and “Protista”) Protista is in “ “ because it is not a true clade -- there is no way to classify all unicellular organisms under this kingdom

Evolution of Kingdoms

A Tree of Life The tree of life shows current hypotheses regarding evolutionary relationships among the taxa within the three domains of life Domain: Archaea (Archaebacteria) Unicellular and prokaryotic Lives in extreme environments Most can only survive in the absence of oxygen Their membranes contain unusual lipids and their cell walls do not contain peptidoglycan Example: Sulfolobus Domain: Bacteria (Eubacteria) Unicellular and prokaryotic Thick, rigid cell walls made of peptidoglycan Ecologically diverse: free-living to dead parasites Some require oxygen and some undergo photosynthesis nitrogen fixation -- turns nitrogen into usable form Example: Salmonella typhimurium

A Tree of Life Domain Eukarya: Fungi Multicellular -- Heterotrophs Cell walls contain chitin Feed on dead or decaying organisms Secretes an enzyme into the dead organism to help break it down to eat (decomposers) Some are unicellular (yeasts) and some are multicellular (mushrooms) Example: molds A Tree of Life Domain Eukarya: “Protists” Unicellular eukaryotes Paraphyletic group -- can be divided into five clades Most are unicellular but some are multicellular (brown algae) Some are photosynthetic and others are heterotrophic Some display characteristics that resemble fungi, plants, or animals Example: Malaria in mosquitoes

A Tree of Life Domain Eukarya: Animalia Multicellular and heterotrophic No cell walls Most can move about at least for some part of their life (motile) Examples: Mammalia -- mammals Reptilia -- reptiles Amphibians Domain Eukarya: Plantae Multicellular Autotrophs -- photosynthesis Cell walls made of cellulose Nonmotile Examples: Angiosperms: flowering plants Gymnosperms: cone or seed bearing plants

The Tree of Life