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Unit 4 Review

Unit 4 Review. Mechanisms of Evolution. Chapter 22. Descent with Modification: A Darwinian View of Life. Linnaeus (classification). Hutton (gradual geologic change). Lamarck (species can change). Malthus (population limits). Cuvier (fossils, extinction). Lyell (modern geology).

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Unit 4 Review

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  1. Unit 4 Review Mechanisms of Evolution

  2. Chapter 22 Descent with Modification: A Darwinian View of Life

  3. 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) Wallace (evolution, natural selection) American Revolution French Revolution U.S. Civil War 1800 1850 1900 1750 1795 Hutton proposes his theory of gradualism. 1798 Malthus publishes “Essay on the Principle of Population.” 1809 Lamarck publishes his theory of evolution. Lyell publishes Principles of Geology. 1830 Darwin travels around the world on HMS Beagle. 1831–1836 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. TheOrigin of Species is published. 1859 1865 Mendel publishes inheritance papers. Figure 22.2 Darwin worked in a historical CONTEXT! • Others’ ideas shaped Darwin’s thinking…

  4. Elements of Darwin’s theory of…Evolution by Natural Selection? • organisms overproduce offspring • members of a population differ in adaptations • competition for limited resources • survival of the fittest • population changes over time • What was Darwin missing? • He couldn’t describe a mechanism for the variation in adaptations. Can you?

  5. Lateral buds Terminal bud Brussels sprouts Cabbage Flower cluster Leaves Cauliflower Kale Flower and stems Stem Broccoli Kohlrabi Wild mustard Figure 22.10 Artificial Selection • Artificial selection: Humans have modified other species by selecting and breeding individuals that possess desired traits

  6. If an environment changes over time • Natural selection may result in adaptation • Does the individual or population evolve? • The alternative to adapting?

  7. Caused by the pesticide?

  8. Human Cat Bat Whale Figure 22.14 Homologous structures: • variations on a structural theme inherited from a common ancestor

  9. Pharyngeal pouches Post-anal tail Chick embryo Human embryo Figure 22.15 • Comparative embryology • Reveals additional anatomical homologies not visible in adult organisms

  10. Vestigial organs: • remnants of structures that served important functions in the organism’s ancestors

  11. Percent of Amino Acids That Are Identical to the Amino Acids in a Human Hemoglobin Polypeptide Species 100% Human Rhesus monkey 95% Mouse 87% Chicken 69% Frog 54% 14% Lamprey Biochemical Comparisions: • Particularly comparison of: • DNA • Proteins Figure 22.16

  12. Figure 22.18 • 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

  13. Chapter 23 The Evolution of Populations

  14. The Modern Synthesis • Population genetics… • Merges & extends Darwin’s & Mendel’s ideas • Focuses on populations as units of evolution

  15. The Hardy-Weinberg Theorem • The Hardy-Weinberg theorem describes a population that is not _________. • evolving • States that allele frequencies in a gene pool will remainconstant from generation to generation, IF: • only Mendelian segregation and recombination of alleles are at work • no evolutionary forces are at work

  16. Five (rarely met) conditions for non-evolving populations… • Extremely large population size • No gene flow • No mutations • Random mating • No natural selection

  17. You reviewed these with the graphical Q’s, right? Hardy-Weinberg Equations - If a population has only two possible alleles at a particular locus, & one is dominant, and no evolutionary forces are working: • p + q = 1 (sum of allele frequencies = 1) • p = frequency of the dominant allele in the population • q = frequency of the recessive allele in the population • p2 + 2pq + q2 = 1 (sum of genotype frequencies = 1) • p2 = frequency of homozygous dominant individuals • q2 = frequency of homozygous recessive individuals • 2pq = frequency of heterozygous individuals

  18. Two processes produce variation in gene pools. What are they? Which one happens FIRST? • 1st: Mutation creates allele variations. • 2nd: Sexual recombinationgenerates new allele combinations via: • crossing over during meiosis • random segregation into gametes • random recombination during fertilization

  19. Three major factors alter allele frequencies and bring about most evolutionary change • Natural selection • Genetic drift • Gene flow

  20. Directional, Disruptive, and Stabilizing Selection • Selection can only act on an individual’s … • phenotype • This allows damaging recessive alleles to hide in ___________, and avoid elimination from the gene pool.

  21. The three modes of selection

  22. Why does complex sexual reproduction persist? • It produces genetic variation that may aid in… • disease resistance • better predator evasion • better feeding efficiency • survival in a changing environment

  23. Why can’t evolution fashion perfect organisms? • Mutations are RANDOM, not chosen • Adaptations are often compromises • Selection can only edit existing variations… • gotta’ work with what we’ve got. • “Perfect” is a moving target… • Predators, prey & competitors keep changing

  24. Chapter 24 The Origin of Species

  25. Speciation • is where microevolution of populations gives way to macroevolution • Macroevolution • Refers to evolutionary change that leads to whole new clades of creatures

  26. Limitations of the Biological Species Concept • The biological species concept cannot be applied to…? • Asexual organisms • Fossils • Organisms with unknown reproductive cycles

  27. Behavioral isolation Habitat isolation Temporal isolation Mechanical isolation Matingattempt Individualsof differentspecies HABITAT ISOLATION MECHANICAL ISOLATION TEMPORAL ISOLATION BEHAVIORAL ISOLATION (g) (b) (d) (e) (f) (a) (c) Figure 24.4 • Prezygotic barriers … continued next slide… . . . . . . .

  28. Gameticisolation Reducehybridfertility Reducehybridviability Hybridbreakdown Viablefertileoffspring Fertilization REDUCED HYBRID VIABILITY GAMETIC ISOLATION HYBRID BREAKDOWN REDUCED HYBRID FERTILITY (k) (j) (m) (l) (i) (h) • ………………postzygotic barriers.

  29. Sympatric speciation. A smallpopulation becomes a new specieswithout geographic separation. Allopatric speciation. A population forms a new species while geographically isolated from its parent population. (a) (b) • Speciation can occur in two ways • Allopatric speciation • Sympatric speciation

  30. A. harrisi A. leucurus Figure 24.6 • Allopatric or Sympatric?

  31. Adaptive Radiation?

  32. ? ?

  33. Evolutionary Novelties • Most novel biological structures • Evolve in many stages from previously existing structures

  34. Hox Genes?? • Associated with the evolution of vertebrates

  35. Most Species are? • Dead Ends!

  36. Chapter 25 Phylogeny and Systematics

  37. Investigating the Tree of Life • Phylogeny: • The evolutionary history of a species or group of related species • Phylogenies are constructed from three major types of evidence: • fossil, morphological, and molecular

  38. Panthera pardus(leopard) Mephitis mephitis (striped skunk) Canis familiaris (domestic dog) Canislupus (wolf) Lutra lutra (European otter) Species Genus Panthera Lutra Canis Mephitis Family Felidae Mustelidae Canidae Carnivora Order Linking Classification and Phylogeny • Systematists depict evolutionary relationships in phylogenetic trees (cladograms) Figure 25.9

  39. Wolf Leopard Domestic cat Common ancestor • “Deeper” branch points represent… • progressively greater amounts of divergence • longer times since divergence

  40. Grouping 1 E J K D H G F C I B A Monophyletic? Paraphyletic? • A valid clade is monophyletic • Signifying that it consists of the ancestor species and all its descendants Figure 25.10a

  41. Outgroup? Derived Character? Cladogram? • Cladograms help determine who branched off when. • Presence or absence of derived characters determines how you build the cladogram.

  42. Mutation rates vary for different types of genes. • Which mutation pattern is best for comparing closely related species? Distantly related species? mtDNA genes rRNA genes

  43. Bacteria Eukarya Archaea 4 Symbiosis of chloroplast ancestor with ancestor of green plants 0 1 3 Symbiosis of mitochondrial ancestor with ancestor of eukaryotes 4 3 Billion years ago 2 2 Possible fusion of bacterium and archaean, yielding ancestor of eukaryotic cells 2 3 1 Last common ancestor of all living things 1 Origin of life 4 The Universal Tree of Life • The tree of life is divided into three great clades called domains: Bacteria, Archaea, and Eukarya • The early history of these domains is complex Figure 25.18

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