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The Macroevolutionary Puzzle
Chapter 19
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Macroevolution The large-scale patterns, trends, and rates of change among families and other more inclusive groups of species
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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
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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
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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
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Radiometric Dating Figure 19.5 Page 309 parent isotope in
newly formed rock after one half-lives after two half-lives Figure 19.5 Page 309
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Geologic Time Scale Boundaries based on transitions in fossil record
Quaternary period Phanerozoic eon Cenozoic era 1 Tertiary period 65 Mesozoic era Cretaceous period Boundaries based on transitions in fossil record 138 Jurassic period 205 Triassic period 210 Paleozoic era Permian period 290 Carboniferous period 370 Devonian period 410 Silurian period 435 Ordovician period 505 Cambrian period Cambrian period 570 Proterozoic eon 2,500 mya Figure 19.4 (2) Page 308 Archean eon and earlier
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Record Is Incomplete Fossils have been found for about 250,000 species
Most species weren’t preserved Record is biased toward the most accessible regions
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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
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Changing Land Masses Figure 19.8c Page 311 420 mya 260 mya 65 mya
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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
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Plate Tectonics Earth’s crust is fractured into plates
Movement of plates driven by upwelling of molten rock Eurasian plate North American plate Pacific plate Pacific plate African plate South American plate Somali plate Nazca plate Indo-Australian plate Antarctic plate Figure 19.8b Page 311
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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
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Morphological Divergence
1 early reptile 2 3 Morphological Divergence 4 5 1 2 3 pterosaur Change from body form of a common ancestor Produces homologous structures 4 1 chicken 2 3 1 2 bat 3 1 4 5 porpoise 2 4 3 5 penguin 2 3 1 2 human 3 4 Figure Page 312 5
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Morphological Convergence
Individuals of different lineages evolve in similar ways under similar environmental pressures Produces analogous structures that serve similar functions
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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
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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 gene mutations
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Similar Vertebrate Embryos
Alterations that disrupted early development have been selected against FISH REPTILE BIRD MAMMAL Figure 19.13a Page 315
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Similar Vertebrate Embryos
Aortic arches Adult shark Early human embryo Two-chambered heart Certain veins Figure 19.13b Page 315
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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
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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
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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
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Molecular Clock Assumption: “Ticks” (neutral mutations) occur at a constant rate Count the number of differences to estimate time of divergence
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Taxonomy Field of biology concerned with identifying, naming, and classifying species Somewhat subjective Information about species can be interpreted differently
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Binomial System Devised by Carl von Linne
Each species has a two-part Latin name First part is generic Second part is specific name
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Higher Taxa Kingdom Phylum Class Order Family Inclusive groupings meant to reflect relationships among species
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Phylogeny The scientific study of evolutionary relationships among species
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Examples of Classification
corn vanilla orchid housefly human Kingdom Genus Species Family Order Class Phylum Plantae Zea Z. mays Poaceae Poales Monocotyledonae Anthophyta Plantae Animalia Musca M. domestica Muscidae Diptera Insecta Anthropoda Animalia Homo H. sapiens Hominidae Primates Mammalia Chordata Anthophyta Monocotyledonae Asparagales Orchidaceae Vanilla V. planifolia Figure Page 318
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Five-Kingdom Scheme Proposed in 1969 by Robert Whittaker Monera
Protista Fungi Plantae Animalia
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Three-Domain Classification
Favored by microbiologists EUBACTERIA ARCHAEBACTERIA EUKARYOTES
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Six-Kingdom Scheme EUBACTERIA ARCHAEBACTERIA PROTISTA FUNGI PLANTAE
ANIMALIA
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Evolutionary Tree Figure 19.21 Page 321 ANIMALS PLANTS arthropods
FUNGI chordates flowering plants conifers annelids round-worms ginkgos sac club mollusks echino-derms fungi fungi cycads horsetails rotifers zygospore- ferns forming flatworms fungi lycophytes cnidarians bryophytes chlorophytes sponges chytrids green algae amoeboid PROTISTANS protozoans (stramenopiles) brown algae red ciliates (alveolates) algae chrysophytes sporozoans oomycotes ? dinoflagellates crown of eukaryotes slime molds (rapid divergences) euglenoids kinetoplastids parabasalids (e.g., Trichomonas) EUBACTERIA diplomonads spirochetes ARCHAEBACTERIA (e.g., Giardia) extreme Gram-positive bacteria chlamydias methanogens halophiles cyanobacteria proteobacteria extreme thermophiles Figure Page 321 molecular origin of life
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