1. EVOLUTION Part I: Change Over Time

2. Misconception: “Evolution is a theory about the origin of life.” Response: Evolutionary theory deals mainly with how life changed after its origin. Science does investigate how life started, but this is not the central focus of evolutionary theory. Most studies of evolution are focused on the branching and diversifying AFTER it started.

3. Misconception: “Evolution is ‘just’ a theory.” Response: Scientific theories are explanations that are based on lines of evidence, enable valid predictions, and have been tested in many ways. In contrast, there is also a popular definition of theory—a “guess” or “hunch.” These conflicting definitions often cause unnecessary confusion about evolution.

4. What is Evolution? processes earliest forms diversityThe processes that have transformed life on earth from it’s earliest forms to the vast diversity that characterizes it today. changegenes over time!! A change in the genes over time!! (What does this mean? What will cause this?) MUTATIONS!

5. Charles Darwin DarwinDarwin read a publication (by Charles Lyell) that talked about how natural forces gradually change Earth’s surface. He wondered if this type of gradual change applied to living organisms…

6. CHARLES DARWIN, cont. In 1831, he signed on as a naturalist for a 5 year expedition that sailed to the Galapagos Islands (off west coast of South America). On the trip, he collected huge numbers of plant and animal specimens Noticed there was tremendous diversity in the organisms he observed From this experience, Darwin developed The theory of natural selection

7. Voyage of the Beagle

8. Galapagos Islands- off coast of Ecuador

9. Darwin’s theory of natural selection Darwin hypothesized: organisms look different because their environments are different. differences allow each species to survive in its particular environment. Example: the firefly beetle “glows” to attract a mate, insuring the survival of the species Example: the vegetarian finch has a beak best suited to eating buds and fruit; an insect-eating finch has a different beak SURVIVAL OF THE FITTEST!!!

10. Section 3 Natural Selection in Action Chapter 7

11. DARWIN’S FINCHES

12. Charles Darwin In 1859, he wroteIn 1859, he wrote: “On the Origin of Species by Means of Natural Selection”“On the Origin of Species by Means of Natural Selection” Two main points in the article: 1.Species were not created in their present form, but evolved from ancestral species. 2.He proposed that NATURAL SELECTION is the mechanism for evolution is the mechanism for evolution

13. 4 Main points of Natural Selection 1.There is variation within a population (we NOW know this is based on CHANGES in the genes- mutations!) 2.Some variations are favorable 3.Not all young produced in each generation can survive 4.Individuals that survive and reproduce are those with favorable variations

14. How does Natural Selection work? Individualsfavorable traits environmentIndividuals with favorable traits are more likely to have and leave more offspring better suited for their environment. THAT is how a population of organisms adapts to their environment!

15. Which variation is favorable? What will the next generations look like? w

16. Misconception: “Natural selection involves organisms ‘trying’ to adapt.” Response: Natural selection leads to adaptation, but the process doesn’t involve “trying.” Natural selection involves genetic variation and selection among variants present in a population. Either an individual has genes that are good enough to survive and reproduce, or it does not—but it can’t get the right genes by “trying.”

18. What does “survival of the fittest” really mean? The fittest member of a population is the individual that is MOST successful in its environment AND produces the most offspring…passes on the most copies of its genes.

19. What are Selective Pressures? Factors that result in selection of specific variations/phenotype: 1.Predation 2.Changes in climate or other environmental factors (food, water, etc) 3.Disease 4.Competition for food, space, reproductive resources …survival means passing on genes.

20.  Individuals do not evolve: populations evolve  Natural selection can amplify or diminish only heritable traits; acquired characteristics cannot be passed on to offspring  Evolution is not goal directed and does not lead to perfection; favorable traits vary as environments change Copyright © 2009 Pearson Education, Inc. Important Points of Evolution:

21.  Rosemary and Peter Grant have worked on Darwin’s finches in the Galápagos for over 20 years –In wet years, small seeds are more abundant and small beaks are favored –In dry years, large strong beaks are favored because large seeds remain http://www.hhmi.org/biointeractive/origin-species-beak- finch Copyright © 2009 Pearson Education, Inc. Scientists observe natural selection in action:

22.  Development of pesticide resistance in insects –Initial use of pesticides favors those few insects that have genes for pesticide resistance –With continued use of pesticides, resistant insects flourish and vulnerable insects die –Proportion of resistant insects increases over time  MRSA & other antibiotic resistant bacteria -Methicillin Resistant Staphylococcus Aureus -Many cases of Staph infections involve this strain; may have occurred because of overuse of antibiotics. Copyright © 2009 Pearson Education, Inc. Natural selection in action, cont.

23. Chromosome with allele conferring resistance to pesticide Additional applications will be less effective, and the frequency of resistant insects in the population will grow Survivors Pesticide application

24. Copyright © 2009 Pearson Education, Inc.   Diploidy preserves variation by “hiding” recessive alleles –A recessive allele is only subject to natural selection when it influences the phenotype in homozygous recessive individuals –For example, cystic fibrosis Why doesn’t natural selection reduce genetic variation in populations by retaining only the most favorable genes (alleles)?

25. 1.Selection can only act on existing variation –Natural selection cannot conjure up new beneficial alleles 2.Evolution is limited by historical constraints –Birds arose as the forelimb of a small dinosaur evolved into a wing Copyright © 2009 Pearson Education, Inc. Natural selection cannot fashion perfect organisms

26. Wing claw (like dinosaur) Feathers Teeth (like dinosaur) Long tail with many vertebrae (like dinosaur)

27. 3.Adaptations are often compromises 4.Chance, natural selection and the environment interact Copyright © 2009 Pearson Education, Inc. Natural selection cannot fashion perfect organisms, cont.

28. Artificial Selection selective breedingThe selective breeding of domesticated plants and animals by man. Question:Question: What’s the ancestor of the domesticated dog? Answer:WOLFAnswer: WOLF

29. Evidence of Evolution 1. Fossil Record: Fossils and the order in which they appear in layers of sedimentary rock (strongest evidence). Which is older- lower or higher in the rocks? 2. Homologous structures: Structures that are similar because of common ancestry (comparative anatomy)

30. Humerus Radius Ulna Carpals Metacarpals Phalanges HumanCatWhaleBat

32. Evidence of Evolution 3. Molecular biology: Sequence comparison of DNA and proteins (amino acids) 4. Taxonomy: Classification of life forms- how they compare & relate to other organisms.

33. http://www.pbs.org/wgbh/nova/evolution /guess-embryo.htmlhttp://www.pbs.org/wgbh/nova/evolution /guess-embryo.html

34.  The sequence of branching on an evolutionary tree is determined by homologous structures (fossil &/or anatomical) and genes (DNA seq data).  Each branch point (# on the following tree) represents the common ancestor of all species that descended from it.  Evolutionary trees are hypotheses that reflect current knowledge of patterns of evolutionary descent Copyright © 2009 Pearson Education, Inc. Patterns of descent are shown on an evolutionary tree

35. Tetrapod limbs Amnion Lungfishes Feathers Amphibians Mammals Lizards and snakes 2 Hawks and other birds Ostriches Crocodiles 1 3 4 5 6 Amniotes Tetrapods Birds Evolutionary Tree of Tetrapods

36.  Phylogeny: evolutionary history of a species or group of species  Hypotheses about phylogenetic relationships can be developed from various lines of evidence –The fossil record provides information about the timing of evolutionary divergences –Homologous morphological traits, behaviors, and molecular sequences also provide evidence of common ancestry Phylogenies are based on homologies in fossils and living organisms Copyright © 2009 Pearson Education, Inc.

37. Species: Felis catus Genus: Felis Family: Felidae Class: Mammalia Order: Carnivora Phylum: Chordata Kingdom: Animalia Bacteria Domain: EukaryaArchaea

38. Order Genus Family Felis Felidae Mephitis Mustelidae Lutra Carnivora Canidae Canis Species Felis catus (domestic cat) Mephitis mephitis (striped skunk) Lutra lutra (European otter) Canis latrans (coyote) Canis lupus (wolf)

39.  A phylogenetic tree is a hypothesis of evolutionary relationships within a group  Cladistics uses shared derived characters to group organisms into clades, including an ancestral species and all its descendents  Shared ancestral characters were present in ancestral groups Shared characters are used to construct phylogenetic trees Copyright © 2009 Pearson Education, Inc.

40.  An important step in cladistics is the comparison of the ingroup (the taxa whose phylogeny is being investigated) and the outgroup (a taxon that diverged before the lineage leading to the members of the ingroup) –The tree is constructed from a series of branch points, represented by the emergence of a lineage with a new set of derived traits –The simplest hypothesis is the most likely phylogenetic tree Copyright © 2009 Pearson Education, Inc. Shared characters are used to construct phylogenetic trees

41. Iguana TAXA Long gestation Duck-billed platypus Kangaroo Beaver CHARACTERS Character Table 0 0 01 0 1 01 Gestation Hair, mammary glands 0 1 11 Long gestation Gestation Hair, mammary glands Iguana Duck-billed platypus Kangaroo Beaver Phylogenetic Tree

42. Iguana TAXA Long gestation Duck-billed platypus Kangaroo Beaver CHARACTERS Character Table 0 0 01 0 1 01 Gestation Hair, mammary glands 0 1 11

43. Build A Cladogram!

44.  The phylogenetic tree of reptiles shows that crocodilians are the closest living relatives of birds –They share numerous features, including four- chambered hearts, singing to defend territories, and parental care of eggs within nests –These traits were likely present in the common ancestor of birds and crocodiles Copyright © 2009 Pearson Education, Inc. Shared characters are used to construct phylogenetic trees

45. Long gestation Gestation Hair, mammary glands Iguana Duck-billed platypus Kangaroo Beaver Phylogenetic Tree

46. Birds Ornithischian dinosaurs Pterosaurs Common ancestor of crocodilians, dinosaurs, and birds Lizards and snakes Crocodilians Saurischian dinosaurs

47.  Molecular systematics compares nucleic acids or other molecules to infer relatedness of taxa –Scientists have sequenced more than 100 billion bases of nucleotides from thousands of species  The more recently two species have branched from a common ancestor, the more similar their DNA sequences should be  The longer two species have been on separate evolutionary paths, the more their DNA should have diverged Copyright © 2009 Pearson Education, Inc. An organism’s evolutionary history is documented in its genome

48. Mutations Mutations are random changes in the DNA (genes) of an organism. Most mutations are unfavorable… occasionally, they may be beneficial and lead to evolutionary changes.

49. Adaptations Inherited characteristics that helps an organism to survive and reproduce. Are the result of evolution by natural selection Giraffe… neck Peacock… flamboyant feathers Bacteria… resistance to antibiotics Human…?

50. Why/how did the giraffe get such a long neck? Explain this using what you have learned about natural selection (the 4 points).

51. 4 Main points of Natural Selection 1.An early giraffe was born with a longer neck…..(a CHANGE in her genes- a mutation!) 2.This giraffe was able to reach the higher, more plentiful leaves on the tree. 3.Many of her siblings with shorter necks did not survive. 4.She survived and had more offspring than other giraffes (& many of them had longer necks!).

52. Gene Pool collection of genesThe total collection of genes in a population at any one time. Indicates diversity and genetic possibilities for the population.

53. To summarize: Mutation allows Adaptation the process leads toof evolution! Speciation

54. Gradualism Small genetic changes occur slowly within a population Darwin originally proposed that evolution occurred at a slow, gradual rate

55. Punctuated equilibrium 1972- Stephen Jay Gould and Niles Eldridge Populations stay stable for long periods of time, interrupted by brief periods of rapid change Environmental change; increased mutation rate Supported by fossil record

56. Gradualism vs Punctuated Equilibrium

57. http://glencoe.mheducation.com/olcweb/c gi/pluginpop.cgi?it=swf::550::400::/sites/ dl/free/0078802849/383939/gradualism_P unctuated_Equilibrium.swf::http://glencoe.mheducation.com/olcweb/c gi/pluginpop.cgi?it=swf::550::400::/sites/ dl/free/0078802849/383939/gradualism_P unctuated_Equilibrium.swf