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The Macroevolutionary Puzzle Chapter 19 Macroevolution The large-scale patterns, trends, and rates of change among families and other more inclusive groups of species 19.1 Fossils • Recognizable evidence of ancient life • What do fossils tell us? – Each species is a mosaic of ancestral and novel traits – All species that ever evolved are related to one another by way of descent Stratification • Fossils are found in sedimentary rock • This type of rock is formed in layers • In general, layers closest to the top were formed most recently Fossilization • Organism becomes buried in ash or sediments • Organic remains become infused with metal and mineral ions • Carbon 14 dating Figure 19.6 Page 309 19.2 Phanerozoic eon Geologic Time Scale • Boundaries based on transitions in fossil record Cenozoic era Mesozoic era Quaternary period 1 Tertiary period 65 Cretaceous period 138 Jurassic period Triassic period Paleozoic era 205 210 Permian period 290 Carboniferous period 370 Devonian period Silurian period Ordovician period Cambrian Cambrianperiod period 410 435 505 570 Proterozoic eon Figure 19.4 (2) Page 308 Archean eon and earlier 2,500 mya 19.3 Continental Drift • Idea that the continents were once joined and have since “drifted” apart • Initially based on the shapes • Wegener refined the hypothesis and named the theoretical supercontinent Pangea Changing Land Masses 420 mya 260 mya 65 mya 10 mya Figure 19.8c Page 311 Evidence of Movement • Wegener cited evidence from glacial deposits and fossils • Magnetic orientations in ancient rocks do not align with the magnetic poles • Discovery of seafloor spreading provided a possible mechanism Plate Tectonics • Earth’s crust is fractured into plates • Movement of plates driven by upwelling of molten rock Eurasian plate North Pacific plate American plate Pacific plate African plate Nazca plate South American plate Somali plate IndoAustralian plate Antarctic plate Figure 19.8b Page 311 19.4 Comparative Morphology • Comparing body forms and structures of major lineages • Guiding principle: – When it comes to introducing change in morphology, evolution tends to follow the path of least resistance Morphological Divergence 4 5 21 3 • Change from body form of a common ancestor • Produces homologous structures 4 pterosaur 1 chicken 2 3 1 2 bat 3 4 1 5 porpoise 2 4 3 5 penguin 2 1 Figure 19.10 Page 312 3 early reptile 21 2 3 4 5 3 human Morphological Convergence • Individuals of different lineages evolve in similar ways under similar environmental pressures • Produces analogous structures that serve similar functions 19.5 Comparative Development • Each animal or plant proceeds through a series of changes in form • Similarities in these stages may be clues to evolutionary relationships • Mutations that disrupt a key stage of development are selected against Altering Developmental Programs • Some mutations shift a step in a way that natural selection favors • Small changes at key steps may bring about major differences • Insertion of transposons or gene mutations Development of Larkspurs • Two closely related species have different petal morphology • They attract different pollinators side view front view D. decorum flower side view front view D. nudicaule flower Figure 19.12 Page 314 Development of Larkspurs Petal length (millimeters) • Petal difference arises from a change in the rate of petal development 6 D. decorum 4 2 D. nudicaule 0 0 10 20 40 Days (after onset of meiosis) Figure 19.12 Page 314 Similar Vertebrate Embryos • Alterations that disrupted early development have been selected against FISH REPTILE BIRD MAMMAL Figure 19.13a Page 315 Similar Vertebrate Embryos Adult shark Aortic arches Two-chambered heart Certain veins Early human embryo Figure 19.13b Page 315 Developmental Changes • Changes in the onset, rate, or time of completion of development steps can cause allometric changes • Adult forms that retain juvenile features Proportional Changes in Skull Chimpanzee Human Figure 19.14b Page 315 19.6 Comparative Biochemistry • Kinds and numbers of biochemical traits that species share is a clue to how closely they are related • Can compare DNA, RNA, or proteins • More similarity means species are more closely related Comparing Proteins • Compare amino acid sequence of proteins produced by the same gene • Human cytochrome c (a protein) – Identical amino acids in chimpanzee protein – Chicken protein differs by 18 amino acids – Yeast protein differs by 56 Sequence Conservation • Cytochrome c functions in electron transport • Deficits in this vital protein would be lethal • Long sequences are identical in wheat, yeast, and a primate Sequence Conservation Yeast Wheat Primate Figure 19.15 Page 316-317 Nucleic Acid Comparison • Use single-stranded DNA or RNA • Hybrid molecules are created, then heated • The more heat required to break hybrid, the more closely related the species Molecular Clock • Assumption: “Ticks” (neutral mutations) occur at a constant rate • Count the number of differences to estimate time of divergence 19.7 Taxonomy • Field of biology concerned with identifying, naming, and classifying species • Somewhat subjective • Information about species can be interpreted differently Binomial System • Devised by Carl von Linne • Each species has a two-part Latin name • First part is generic • Second part is specific name Higher Taxa • • • • • Kingdom Phylum Class Order Family • Inclusive groupings meant to reflect relationships among species Phylogeny • The scientific study of evolutionary relationships among species • Practical applications – Allows predictions about the needs or weaknesses of one species on the basis of its known relationship to another Examples of Classification corn Kingdom Phylum Class Order Family Genus Species Plantae Anthophyta Monocotyledonae Poales Poaceae Zea Z. mays vanilla orchid Plantae Anthophyta Monocotyledonae Asparagales Orchidaceae Vanilla V. planifolia housefly Animalia Anthropoda Insecta Diptera Muscidae Musca M. domestica human Animalia Chordata Mammalia Primates Hominidae Homo H. sapiens Figure 19.17 Page 318 A Cladogram shark mammal crocodile fur lungs heart bird feathers Five-Kingdom Scheme • Proposed in 1969 by Robert Whittaker Monera Protista Fungi Plantae Animalia Three-Domain Classification • Favored by microbiologists EUBACTERIA ARCHAEBACTERIA EUKARYOTES Six-Kingdom Scheme EUBACTERIA ARCHAEBACTERIA PROTISTA FUNGI PLANTAE ANIMALIA