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Unformatted text preview: EVIDENCE OF EVIDENCE OF EVOLUTION AND MACROEVOLUTION CHAPTER 17 EVOLUTIONARY THEORIES EVOLUTIONARY THEORIES Widely used to interpret the past and present, and even to predict the future Reveal connections between the geological record, fossil record, and organism diversity EARLY SCIENTIFIC THEORIES EARLY SCIENTIFIC THEORIES Hippocrates ­ All aspects of nature can be traced to their underlying causes Aristotle ­ Each organism is distinct from all the rest and nature is a continuum or organization (The “The Great Chain of Being) Discoveries contradictory to early beliefs Discoveries contradictory to early beliefs Biogeography Comparative anatomy Geologic discoveries BIOGEOGRAPHY BIOGEOGRAPHY Size of the known world expanded enormously in the 15th century Discovery of new organisms in previously unknown places could not be explained by accepted beliefs How did species get from center of creation to all these places? ie: flightless birds and spiny cacti/spiny spurge Fig. 17-3b, p.262 Fig. 17-3c, p.262 Fig. 17-3d, p.262 Fig. 17-3e, p.262 COMPARATIVE MORPHOLOGY COMPARATIVE MORPHOLOGY Study of similarities and differences in body plans of major groups Puzzling patterns: Animals as different as whales and bats have similar bones in forelimbs Some parts seem to have no function Comparative Morphology coccyx ankle bone Fig. 17-4a, p.263 fossilized ankle bone Fig. 17-4b, p.263 GEOLOGIC DISCOVERIES/FOSSILS GEOLOGIC DISCOVERIES/FOSSILS Similar rock layers throughout world Certain layers contain fossils Deeper layers contain simpler fossils than shallow layers Some fossils seem to be related to known species Fig. 17-5, p.263 19th Century ­ New Theories 19th Century ­ New Theories Scientists attempt to reconcile evidence of change with traditional belief in a single creation event Two examples Georges Cuvier ­ multiple catastrophes Jean Lamarck ­ inheritance of acquired characteristics Darwin’s Voyage Fig. 17-6a, p.264 Darwin’s Voyage Darwin’s Voyage At age 22, Charles Darwin began a five­year, round­the­world voyage aboard the Beagle (1831) In his role as ship’s naturalist, he collected and examined the species that inhabited the regions the ship visited Also during his voyage he read writings by Malthus and Lyell. Voyage of the Beagle route of Beagle EQUATOR Galapagos Islands Fig. 17-6c, p.265 Galapagos Islands Volcanic islands far off coast of Ecuador All inhabitants are descended from species that arrived on islands from elsewhere Ie: Galapagos Finch pp.267 Darwin Wolf Pinta Marchena Santiago Genovesa Fernandina EQUATOR Bartolome Seymour Rabida Blatra Pinzon Santa Cruz Santa Fe Tortuga San Cristobal Espanola Floreana Fig. 17-6d, p.265 Isabela Fig. 17-7b, p.266 ARMADILLO . ARMADILLO . Fig. 17-7a, p.266 The Theory of Uniformity The Theory of Uniformity Lyell’s Principles of Geology Subtle, repetitive processes of change had shaped Earth Challenged the view that Earth was only 6,000 years old Malthus ­ Struggle to Survive Malthus ­ Struggle to Survive Thomas Malthus, a clergyman and economist, wrote an essay that Darwin read on his return to England Argued that as population size increases, resources dwindle, the struggle to live intensifies, and conflict increases Galapagos Finches Galapagos Finches Darwin observed finches with a variety of lifestyles and body forms On his return, he learned that there were 13 species He attempted to correlate variations in their traits with environmental challenges Variation in Populations Variation in Populations All individuals have the same genes that specify the same assortment of traits Most genes occur in different forms (alleles) that produce different phenotypes Some phenotypes compete better than others Change over Time Change over Time Over time, the alleles that produce the most successful phenotypes will increase in the population Less successful alleles will become less common Change leads to increased fitness Increased adaptation to environment Darwin’s Theory Darwin’s Theory “Evolution by Natural Selection” A population can change over time when individuals differ in one or more heritable traits that are responsible for differences in the ability to survive and reproduce. See page 267 Alfred Wallace Alfred Wallace Naturalist who arrived at the same conclusions Darwin did Wrote to Darwin describing his views Prompted Darwin to finally present his ideas in a formal paper MACROEVOLUTION MACROEVOLUTION Large scale patterns, rates of change, and trends among lineages. Evidences of evolution found in: Anatomical evidence (compare morphology) Embryology and Development Protein comparisons (Serology) DNA comparisons Fossil evidence 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 DIVERGENT EVOLUTION . STRUCTURES THAT STEMED FROM A COMMON ANCESTOR DIVERGENT MORPHOLOGY “HOMOLOGOUS STRUCTURES” . Fig. 17-17, p.274 CONVERGENT EVOLUTION CONVERGENT EVOLUTION MORPHOLOGICAL CONVERGENCE “ANALOGOUS STRUCTURES” STRUCTURES THAT PERFORM A SIMILAR FUNCTION FOR THE ORGANISM BUT STEMED FROM DIFFERENT SOURCES. IE: A BIRD WING AND A BEE WING THE STREAMLINE SHAPE OF A SHARK (FISH) AND A PENGUIN (BIRD) EMBRYOLOGICAL EVIDENCE EMBRYOLOGICAL EVIDENCE THE FIRST EMBRYONIC STAGES OF ALL ANIMALS WITH BACKBONES ARE IDENTICAL Similar Vertebrate Embryos Similar Vertebrate Embryos Alterations that disrupted early development have been selected against FISH REPTILE BIRD MAMMAL Similar Vertebrate Embryos Similar Vertebrate Embryos Adult shark Aortic arches Two-chambered heart Certain veins Early human embryo 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 . ONE SLIGHT MUTATION IN GROWTH RATE OF A PART CAN CHANGE APPEARANCE IE: 1) THE DEVELOPMENT OF A HUMAN VS. A CHIMP SKULL 2) A SLIGHT MUTATION HAS CHANGED THE FLORAL DEVELOPMENT IN SOME FLOWER SPECIES (THE FIELD MUSTARD OR THE COMMON WALL CRESS OR DIFFERENT SPECIES OF LARKSPURS) adult proportions in infant Fig. 17-20a, p.276 proportions in infant adult Fig. 17-20b, p.276 Development of Larkspurs 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 . FIELD MUSTARD a b COMMON WALL CRESS c d Fig. 17-19, p.276 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 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 Comparative Biochemistry (COMPARE PROTEINS) p.278 Nucleic Acid Comparison Nucleic Acid Comparison Use single­stranded DNA or RNA Hybrid molecules are created, then heated The more heat required to break hybrid, the more closely related the species Molecular Clock Molecular Clock Assumption: “Ticks” (neutral mutations) occur at a constant rate Count the number of differences to estimate time of divergence FOSSILS: Stratification FOSSILS: 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 These generally look the most like present day organisms Stratification Fig. 17-11, p.269 Fig. 17-10b, p.268 Fossilization Fossilization Organism becomes buried in ash or sediments Organic remains become infused with metal and mineral ions Carbon 14 dating Fig.19.6, p. 309 Midnight, origin of life 11:59:40 PM, first humans origin of prokaryotes dinosuars, flowering plants origin of eukaryotes Geologic Time Scale Fig. 17-14, p.271 Fig. 17-13, p.271 Changing Land Masses a 420 mya b 260 mya c 65 mya d 10 mya Fig. 17-16a-d, p.273 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 Evidence of Movement 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 island arc oceanic crust oceanic ridge trench continental crust lithosphere (solid layer of mantle) hot spot athenosphere (plastic layer of mantle) subducting plate Fig. 17-15b, p.272 Plate Tectonics Plate Tectonics Earth’s crust is fractured into plates Movement of plates driven by upwelling of molten rock Pacific plate North American plate African plate Nazca plate South American plate Eurasian plate Pacific plate Somali plate IndoAustralian plate Antarctic plate ...
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