Evolution and systematics.ppt

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Evolution and systematics.ppt

  1. 1. Descent with Modification: A Darwinian View of Life PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  2. 2. •  The Origin of Species –  Focused biologists’ attention on the great diversity of organisms Figure 22.1 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  3. 3. •  Darwin made two major points in his book –  He presented evidence that the many species of organisms presently inhabiting the Earth are descendants of ancestral species –  He proposed a mechanism for the evolutionary process, natural selection Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  4. 4. •  The historical context of Darwin’s life and ideas Linnaeus (classification) Hutton (gradual geologic change) Lamarck (species can change) Malthus (population limits) Cuvier (fossils, extinction) Lyell (modern geology) Darwin (evolution, nutural selection) Mendel (inheritance) American Revolution 1750 Wallace (evolution, natural selection) French Revolution U.S. Civil War 1800 1850 1900 1795 Hutton proposes his theory of gradualism. 1798 Malthus publishes “Essay on the Principle of Population.” 1809 Lamarck publishes his theory of evolution. 1830 Lyell publishes Principles of Geology. 1831–1836 Darwin travels around the world on HMS Beagle. 1837 Darwin begins his notebooks on the origin of species. 1844 Darwin writes his essay on the origin of species. 1858 Wallace sends his theory to Darwin. 1859 The Origin of Species is published. 1865 Mendel publishes inheritance papers. Figure 22.2 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  5. 5. Resistance to the Idea of Evolution •  The Origin of Species –  Shook the deepest roots of Western culture –  Challenged a worldview that had been prevalent for centuries Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  6. 6. The Scale of Nature and Classification of Species •  The Greek philosopher Aristotle –  Viewed species as fixed and unchanging •  The Old Testament of the Bible –  Holds that species were individually designed by God and therefore perfect Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  7. 7. •  Carolus Linnaeus –  Interpreted organismal adaptations as evidence that the Creator had designed each species for a specific purpose –  Was a founder of taxonomy, classifying life’s diversity “for the greater glory of God” Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  8. 8. Theories of Gradualism •  Gradualism –  Is the idea that profound change can take place through the cumulative effect of slow but continuous processes Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  9. 9. •  Geologists Hutton and Lyell –  Perceived that changes in Earth’s surface can result from slow continuous actions still operating today –  Exerted a strong influence on Darwin’s thinking Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  10. 10. Lamarck’s Theory of Evolution •  Lamarck hypothesized that species evolve –  Through use and disuse and the inheritance of acquired traits –  But the mechanisms he proposed are unsupported by evidence Figure 22.4 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  11. 11. •  Darwin’s interest in the geographic distribution of species –  Was kindled by the Beagle’s stop at the Galápagos Islands near the equator west of South America England NORTH AMERICA EUROPE ATLANTIC OCEAN PACIFIC OCEAN Galápagos Islands AUSTRALIA Cape of Good Hope Cape Horn Figure 22.5 HMS Beagle in port SOUTH AMERICA Andes Darwin in 1840, after his return AFRICA Tierra del Fuego Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Tasmania New Zealand
  12. 12. The Origin of Species •  Darwin developed two main ideas –  Evolution explains life’s unity and diversity –  Natural selection is a cause of adaptive evolution Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  13. 13. Descent with Modification •  The phrase descent with modification –  Summarized Darwin’s perception of the unity of life –  States that all organisms are related through descent from an ancestor that lived in the remote past Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  14. 14. •  In the Darwinian view, the history of life is like a tree Sirenia Hyracoidea (Manatees (Hyraxes) and relatives) Figure 22.7 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Mammuthus Stegodon Platybelodon Mammut Barytherium Deinotherium Elephas Loxodonta Loxodonta maximus africana cyclotis (Africa) (Asia) (Africa) Moeritherium Millions of years ago Years ago –  With multiple branchings from a common trunk to the tips of the youngest twigs that represent the diversity of living organisms
  15. 15. Natural Selection and Adaptation •  Evolutionary biologist Ernst Mayr –  Has dissected the logic of Darwin’s theory into three inferences based on five observations Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  16. 16. •  Observation #1: For any species, population sizes would increase exponentially –  If all individuals that are born reproduced successfully Figure 22.8 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  17. 17. •  Observation #2: Nonetheless, populations tend to be stable in size –  Except for seasonal fluctuations •  Observation #3: Resources are limited •  Inference #1: Production of more individuals than the environment can support –  Leads to a struggle for existence among individuals of a population, with only a fraction of their offspring surviving Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  18. 18. •  Observation #4: Members of a population vary extensively in their characteristics –  No two individuals are exactly alike Figure 22.9 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  19. 19. •  Observation #5: Much of this variation is heritable •  Inference #2: Survival depends in part on inherited traits –  Individuals whose inherited traits give them a high probability of surviving and reproducing are likely to leave more offspring than other individuals Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  20. 20. •  Inference #3: This unequal ability of individuals to survive and reproduce –  Will lead to a gradual change in a population, with favorable characteristics accumulating over generations Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  21. 21. Artificial Selection •  In the process of artificial selection –  Humans have modified other species over many generations by selecting and breeding individuals that possess desired traits Terminal bud Lateral buds Brussels sprouts Cabbage Flower cluster Leaves Cauliflower Kale Flower and stems Broccoli Stem Wild mustard Figure 22.10 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Kohlrabi
  22. 22. Summary of Natural Selection •  Natural selection is differential success in reproduction –  That results from the interaction between individuals that vary in heritable traits and their environment Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  23. 23. •  If an environment changes over time –  Natural selection may result in adaptation to these new conditions Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  24. 24. The Evolution of Drug-Resistant HIV •  In humans, the use of drugs –  Selects for pathogens that through chance mutations are resistant to the drugs’ effects •  Natural selection is a cause of adaptive evolution Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  25. 25. •  Researchers have developed numerous drugs to combat HIV Percent of HIV resistant to 3TC –  But using these medications selects for viruses resistant to the drugs Patient No. 1 Patient No. 2 Patient No. 3 Weeks Figure 22.13 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  26. 26. Molecular Homologies •  Biologists also observe homologies among organisms at the molecular level –  Such as genes that are shared among organisms inherited from a common ancestor Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  27. 27. •  Anatomical resemblances among species –  Are generally reflected in their molecules, their genes, and their gene products Species Percent of Amino Acids That Are Identical to the Amino Acids in a Human Hemoglobin Polypeptide 100% Human Rhesus monkey 95% Mouse 87% Chicken 69% Frog Figure 22.16 Lamprey Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 54% 14%
  28. 28. •  The Darwinian view of life –  Predicts that evolutionary transitions should leave signs in the fossil record •  Paleontologists –  Have discovered fossils of many such transitional forms Figure 22.18 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  29. 29. What Is Theoretical about the Darwinian View of Life? •  In science, a theory –  Accounts for many observations and data and attempts to explain and integrate a great variety of phenomena Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  30. 30. •  New information has revised our understanding of the tree of life •  Molecular Data –  Have provided new insights in recent decades regarding the deepest branches of the tree of life Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  31. 31. Previous Taxonomic Systems •  Early classification systems had two kingdoms –  Plants and animals Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  32. 32. •  Robert Whittaker proposed a system with five kingdoms –  Monera, Protista, Plantae, Fungi, and Animalia Plantae Fungi Protista Figure 26.21 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Monera Animalia
  33. 33. Reconstructing the Tree of Life: A Work in Progress •  A three domain system –  Has replaced the five kingdom system –  Includes the domains Archaea, Bacteria, and Eukarya •  Each domain –  Has been split by taxonomists into many kingdoms Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  34. 34. Figure 26.22 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Domain Archaea Domain Bacteria Universal ancestor Domain Eukarya Charophyceans Chlorophytes Red algae Cercozoans, radiolarians Stramenopiles (water molds, diatoms, golden algae, brown algae) Chapter 27 Alveolates (dinoflagellates, apicomplexans, ciliates) Euglenozoans Diplomonads, parabasalids Euryarchaeotes, crenarchaeotes, nanoarchaeotes Korarchaeotes Gram-positive bacteria Cyanobacteria Spirochetes Chlamydias Proteobacteria •  One current view of biological diversity Chapter 28
  35. 35. Figure 26.21 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Plants Fungi Animals Bilaterally symmetrical animals (annelids, arthropods, molluscs, echinoderms, vertebrates) Cnidarians (jellies, coral) Chapter 32 Sponges Chapter 31 Choanoflagellates Club fungi Sac fungi Chapter 28 Arbuscular mycorrhizal fungi Zygote fungi Chytrids Chapter 30 Amoebozoans (amoebas, slime molds) Angiosperms Gymnosperms Seedless vascular plants (ferns) Bryophytes (mosses, liverworts, hornworts) Chapter 29 Chapters 33, 34
  36. 36. •  Concept 25.2: Phylogenetic systematics connects classification with evolutionary history •  Taxonomy –  Is the ordered division of organisms into categories based on a set of characteristics used to assess similarities and differences Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  37. 37. Binomial Nomenclature •  Binomial nomenclature –  Is the two-part format of the scientific name of an organism –  Was developed by Carolus Linnaeus Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  38. 38. •  The binomial name of an organism or scientific epithet –  Is latinized –  Is the genus and species Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  39. 39. Hierarchical Classification •  Linnaeus also introduced a system –  For grouping species in increasingly broad categories Panthera Species pardus Panthera Genus Felidae Family Carnivora Order Class Phylum Kingdom Figure 25.8 Domain Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Mammalia Chordata Animalia Eukarya
  40. 40. Linking Classification and Phylogeny •  Systematists depict evolutionary relationships Species Panthera Order Family Panthera Mephitis Canis Canis Lutra lutra pardus mephitis familiaris lupus (European (leopard) (striped skunk) otter) (domestic dog) (wolf) Genus –  In branching phylogenetic trees Mephitis Felidae Lutra Mustelidae Carnivora Figure 25.9 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Canis Canidae
  41. 41. •  Each branch point –  Represents the divergence of two species Leopard Domestic cat Common ancestor Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  42. 42. •  “Deeper” branch points –  Represent progressively greater amounts of divergence Wolf Leopard Common ancestor Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Domestic cat
  43. 43. •  Concept 25.3: Phylogenetic systematics informs the construction of phylogenetic trees based on shared characteristics •  A cladogram –  Is a depiction of patterns of shared characteristics among taxa •  A clade within a cladogram –  Is defined as a group of species that includes an ancestral species and all its descendants •  Cladistics –  Is the study of resemblances among clades Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  44. 44. Cladistics •  Clades –  Can be nested within larger clades, but not all groupings or organisms qualify as clades Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  45. 45. •  A valid clade is monophyletic –  Signifying that it consists of the ancestor species and all its descendants Grouping 1 E D J H G F C K I B A Figure 25.10a (a) Monophyletic. In this tree, grouping 1, consisting of the seven species B–H, is a monophyletic group, or clade. A monophyletic group is made up of an ancestral species (species B in this case) and all of its descendant species. Only monophyletic groups qualify as legitimate taxa derived from cladistics. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  46. 46. •  A paraphyletic clade –  Is a grouping that consists of an ancestral species and some, but not all, of the descendants Grouping 2 G E D C J H K I F B A Figure 25.10b (b) Paraphyletic. Grouping 2 does not meet the cladistic criterion: It is paraphyletic, which means that it consists of an ancestor (A in this case) and some, but not all, of that ancestor’s descendants. (Grouping 2 includes the descendants I, J, and K, but excludes B–H, which also descended from A.) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  47. 47. •  A polyphyletic grouping –  Includes numerous types of organisms that lack a common ancestor Grouping 3 D E G J H I F C K B A Figure 25.10c (c) Polyphyletic. Grouping 3 also fails the cladistic test. It is polyphyletic, which means that it lacks the common ancestor of (A) the species in the group. Furthermore, a valid taxon that includes the extant species G, H, J, and K would necessarily also contain D and E, which are also descended from A. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  48. 48. Shared Primitive and Shared Derived Characteristics •  In cladistic analysis –  Clades are defined by their evolutionary novelties Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  49. 49. •  A shared primitive character –  Is a homologous structure that predates the branching of a particular clade from other members of that clade –  Is shared beyond the taxon we are trying to define Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  50. 50. •  A shared derived character –  Is an evolutionary novelty unique to a particular clade Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  51. 51. TAXA A B C D E Apomorphy for taxon D Apomorphies for taxa B&C TIME Apomorphy for taxa B-F Cladogram or Phylogenetic Tree F
  52. 52. Similarity due to common ancestry- similar DNA sequences Intraindividual homology? Similarity by common ancestry of features within an individual, e.g., carpels and leaves (common ancestry by genes)
  53. 53. Similarity not by common ancestry. Types? Convergence - independent evolution of a similar feature in 2 or more lineages. Reversal - loss of a derived feature with reestablishment of ancestral feature.
  54. 54. Convergence - Stem succulence and “spines” in Cactaceae and Euphorbia spp.

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