The Macroevolutionary Puzzle Chapter 19

Asteroid Impacts Many past catastrophic impacts altered the course of evolution K–T boundary 2.3 million years ago in southern Pacific Ocean

Macroevolution The large-scale patterns, trends, and rates of change among families and other more inclusive groups of species

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

Radiometric Dating after two half-lives after one half-lives parent isotope in newly formed rock Figure 19.5 Page 309

Geologic Time Scale Boundaries based on transitions in fossil record Cambrian period Proterozoic eon 2,500 mya Archean eon and earlier Ordovician period Silurian period Devonian period Carboniferous period Permian period Cretaceous period Tertiary period Quaternary period Cambrian period Jurassic period Triassic period Paleozoic era Mesozoic era Cenozoic era Phanerozoic eon Figure 19.4 (2) Page 308

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

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 10 mya65 mya260 mya420 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 Pacific plate Nazca plate North American plate South American plate Eurasian plate African plate Somali plate Pacific plate Indo- Australian plate Antarctic plate Figure 19.8b Page 311

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 Change from body form of a common ancestor Produces homologous structures early reptile pterosaur chicken bat porpoise penguin human Figure Page 312

Morphological Convergence Individuals of different lineages evolve in similar ways under similar environmental pressures Produces analogous structures that serve similar functions

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 front viewside view D. decorum flower front viewside view D. nudicaule flower Figure Page 314

Development of Larkspurs Petal difference arises from a change in the rate of petal development Petal length (millimeters) Days (after onset of meiosis) D. decorum D. nudicaule Figure Page 314

Similar Vertebrate Embryos Alterations that disrupted early development have been selected against FISHREPTILEBIRDMAMMAL Figure 19.13a Page 315

Similar Vertebrate Embryos Adult shark Early human embryo Two-chambered heart Aortic arches Certain veins 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

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 Page

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

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 Kingdom Genus Species Family Order Class Phylum Plantae Zea Z. mays Poaceae Poales Monocotyledonae Anthophyta Plantae Vanilla V. planifolia Orchidaceae Asparagales Monocotyledonae Anthophyta Animalia Musca M. domestica Muscidae Diptera Insecta Anthropoda Animalia Homo H. sapiens Hominidae Primates Mammalia Chordata cornvanilla orchidhouseflyhuman Figure Page 318

A Cladogram heart lungs feathers fur sharkmammalcrocodilebird

Five-Kingdom Scheme Proposed in 1969 by Robert Whittaker Monera Protista Fungi Plantae Animalia

Three-Domain Classification Favored by microbiologists EUBACTERIAARCHAEBACTERIAEUKARYOTES

Six-Kingdom Scheme EUBACTERIAARCHAEBACTERIAPROTISTAFUNGIPLANTAEANIMALIA

Constructing A Cladogram JawsLimbsHairLungsTailShell Lamprey Turtle Cat Gorilla Lungfish Trout Human TaxonTraits (Characters) JawsLimbsHairLungsTailShell Lamprey Turtle Cat Gorilla Lungfish Trout Human TaxonTraits (Characters) In-text figure Page 320

Constructing a Cladogram gorillahumanturtlelungfishtrout jaws lamprey lungs limbs hair tail loss cat Figure 19.20e Page 320

Evolutionary Tree extreme thermophiles halophiles methanogens cyanobacteria ARCHAEBACTERIA PROTISTANS FUNGI PLANTS ANIMALS club fungi sac fungi zygospore- forming fungi echino- derms chordates annelids mollusks flatworms sponges cnidarians flowering plants conifers horsetails lycophytes ferns bryophytes sporozoans green algae amoeboid protozoans slime molds ciliates red algae brown algae chrysophytes cycads ginkgos rotifers arthropods round- worms chytrids oomycotes euglenoids dinoflagellates Gram-positive bacteria spirochetes chlamydias proteobacteria ? crown of eukaryotes (rapid divergences) molecular origin of life EUBACTERIA parabasalids diplomonads (e.g., Giardia) (alveolates) (stramenopiles) chlorophytes kinetoplastids extreme (e.g., Trichomonas) Figure Page 321

Transitional Forms Dromaeosaurus Archaeopteryx