Copyright © 2005 Pearson Prentice Hall, Inc. Chapter 18 Systematics: Seeking Order Amidst Diversity

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How Are Organisms Named and Classified? Classification of Selected Organisms, Reflecting Their Degree of Relatedness* (T18.1 p. 346)

Copyright © 2005 Pearson Prentice Hall, Inc. Three species of bluebird (F18.1 p. 346)

Copyright © 2005 Pearson Prentice Hall, Inc. How Are Organisms Named and Classified? Classification Originated as a Hierarchy of Categories Systematists Identify Features That Reveal Evolutionary Relationships Anatomy Plays a Key Role in Systematics –Microscopic structures may be used to classify organisms (F18.2 p. 347)

Copyright © 2005 Pearson Prentice Hall, Inc. How Are Organisms Named and Classified? Molecular Similarities Are Also Useful for Reconstructing Phylogeny –Human & chimp chromosomes are similar (F18.3 p. 348)

Copyright © 2005 Pearson Prentice Hall, Inc. What Are the Domains of Life? The Five-Kingdom System Improved Classification A Three-Domain System More Accurately Reflects Life’s History –Two domains of prokaryotic organisms (F 18.4 p. 349) –The tree of life (F18.5 p. 349)

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BACTERIA ARCHAEA EUKARYA animals fungi plants protists The tree of life (F18.5 p. 349)

Copyright © 2005 Pearson Prentice Hall, Inc. What Are the Domains of Life? Kingdom-Level Classification Remains Unsettled –Relatedness can be determined by comparing DNA sequences (FE18.1 p. 350) –A closer look at the eukaryotic tree of life (F18.6 p. 351)

Copyright © 2005 Pearson Prentice Hall, Inc. PLANTAEANIMALIA FUNGI “PROTISTS” to Archaea to Bacteria Sarcomastigophora (zooflagellates, sarcodines) Apicomplexa (sporozoans) Pyrrophyta (dinoflagellates) Ciliophora (ciliates) Euglenophyta (euglenoids) Phaeophyta (brown algae) Oomycota (water molds) Rhodophyta (red algae) Chlorophyta (green algae) Bryophyta (liverworts, mosses) Pteridophyta (ferns) Coniferophyta (conifers) Anthophyta (flowering plants) Zygomycota (zygote fungi) Ascomycota (sac fungi) Basidiomycota (club fungi) Porifera (sponges) Cnidaria (hydras, anemones, jellyfish) Platyhelminthes (flatworms) Mollusca (snails, clams, squid) Annelida (segmented worms) Arthropoda (insects, arachnids, crustaceans) Echinodermata (sea stars, sea urchins, sea cucumbers) Chordata (tunicates, lancelets, vertebrates) Activity 18.2

Copyright © 2005 Pearson Prentice Hall, Inc. HumanChimp Pygmy chimp Gorilla Orangutan Common gibbon Evolutionary Relationships by DNA Analysis

Copyright © 2005 Pearson Prentice Hall, Inc. Why Do Classifications Change? Species Designations Change When New Information Is Discovered The Biological Species Definition Can Be Difficult or Impossible to Apply –The Phylogenetic Species Concept Offers an Alternative Definition

Copyright © 2005 Pearson Prentice Hall, Inc. How Many Species Exist? The black-faced lion tamarin (F18.7 p. 352) Reptiles are not a monophyletic group (F18.8 p. 353) Evolutionary analysis helps reveal the origin of HIV (F18.9 p. 354)

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1234 A 1234 A CrocodilesBirdsSnakesLizardsTurtles 1-4 are monophyletic on the left (ALL the descendants of one common ancestor) But NOT on the right Reptiles are not monophyletic!!

Copyright © 2005 Pearson Prentice Hall, Inc A 1234 A

Crocodiles Birds SnakesLizardsTurtles

Copyright © 2005 Pearson Prentice Hall, Inc. HIV-2 (strain 2) SIV-pig-tailed macaque SIV-sooty mangeby monkey HIV-2 (strain 1) SIV-mandrill SIV-chimpanzee (strain 2) HIV-1 (strain 2) SIV-chimpanzee (strain 1) HIV-1 (strain 1) Human HIVs Do Not Cluster 2 Separate Cross- Species Jumps: One of HIV-1 & One of HIV-2