2. EVOLUTION & SPECIATION

3. VOCABULARY REVIEW EVOLUTION – CHANGE OVER TIME EVOLUTION – CHANGE OVER TIME NATURAL SELECTION - INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE. NATURAL SELECTION - INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE. –A.K.A. “SURVIVAL OF THE FITTEST”

4. Charles Darwin Wrote in 1859“On the Origin of Species by Means of Natural Selection”Wrote in 1859:“On the Origin of Species by Means of Natural Selection” Two main points:Two main points: 1.Species were not created in their present form, but evolved from ancestral species. 2.Proposed a mechanism for evolution: NATURAL SELECTION

5. Natural Selection Individualsfavorabletraits environmentIndividuals with favorable traits are more likely to leave more offspring better suited for their environment. “Differential Reproduction”Also known as “Differential Reproduction” Example:Example: English peppered moth (Biston betularia) Biston betulariaBiston betularia - light and dark phases

6. Darwin’s 5 points 1.Population has variations. 2.Some variations are favorable. 3.More offspring are produced than survive 4.Those that survive have favorable traits. 5.A population will change over time.

7. 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

8. Evidence of Evolution 1. Biogeography: Geographical distribution of species. 2. Fossil Record: Fossils and the order in which they appear in layers of sedimentary rock (strongest evidence).

9. NEW VOCABULARY POPULATION – GROUP OF INDIVIDUALS OF SAME SPECIES THAT INTERBREED POPULATION – GROUP OF INDIVIDUALS OF SAME SPECIES THAT INTERBREED GENE POOL – COMMON GROUP OF ALL GENES PRESENT IN A POPULATION GENE POOL – COMMON GROUP OF ALL GENES PRESENT IN A POPULATION

10. Gene Pool Combined genetic info. of all members Allele frequency is # of times alleles occur

11. Variation in Populations 2 processes can lead to this: Mutations - change in DNA sequence Gene Shuffling – from sexual reproduction

12. a. Bottleneck Effect Genetic drift disasterreduces population sizeGenetic drift (reduction of alleles in a population) resulting from a disaster that drastically reduces population size. Examples:Examples: 1.Earthquakes 2.Volcano’s

13. Genetic drift can cause big losses of genetic variation for small populations. It reduces genetic variation. Population bottlenecks occur when a population’s size is reduced for at least one generation. This is illustrated by the bags of marbles shown below, where, in generation 2, an unusually small draw creates a bottleneck Reduced genetic variation means that the population may not be able to adapt to new selection pressures, such as climatic change or a shift in available resources, because the genetic variation that selection would act on may have already drifted out of the population. An example of a bottleneck: Northern elephant seals have reduced genetic variation probably because of a population bottleneck humans inflicted on them in the 1890s. Hunting reduced their population size to as few as 20 individuals at the end of the 19th century. Their population has since rebounded to over 30,000—but their genes still carry the marks of this bottleneck: they have much less genetic variation than a population of southern elephant seals that was not so intensely hunted.

14. Genetic Drift changes populations……. Random change in allele frequency causes an allele to become common Random change in allele frequency causes an allele to become common

15. Founder Effect: a cause of genetic drift attributable to colonization by a limited number of individuals from a parent population Founder Effect: a cause of genetic drift attributable to colonization by a limited number of individuals from a parent population

16. Non-random mating: inbreeding and assortive mating (both shift frequencies of different genotypes) Non-random mating: inbreeding and assortive mating (both shift frequencies of different genotypes) Assortative mating occurs when individuals select mates non-randomly from within their population, on the basis of a trait that both they and their mates express.

17. Founder Effect Genetic driftcolonizationGenetic drift resulting from the colonization of a new location by a small number of individuals. random changeResults in random change of the gene pool. Example:Example: 1.Islands (first Darwin finch)

18. Five Mechanisms of Microevolution 1.Islands (first Darwin finch) 2. Gene Flow: Tgain or loss of alleles movement The gain or loss of alleles from a population by the movement of individuals or gametes. Immigration or emigrationImmigration or emigration.

19. Gene Flow: genetic exchange due to the migration of fertile individuals or gametes between populations (reduces differences between populations) Gene Flow: genetic exchange due to the migration of fertile individuals or gametes between populations (reduces differences between populations)

20. Five Mechanisms of Microevolution 3. Mutation: Change in an organism’s DNA that creates a new allele. 4. Non-random mating: The selection of mates other than by chance. 5. Natural selection: Differential reproduction.

21. Modes of Action Natural selectionthree modesNatural selection has three modes of action: 1.Stabilizing selection 2.Directional selection 3.Diversifying selection Number of Individuals Size of individuals Small Large

22. 1.Stabilizing Selection Actsextremesfavors intermediateActs upon extremes and favors the intermediate. Number of Individuals Size of individuals Small Large

23. 2.Directional Selection Favorsone extremeFavors variants of one extreme. Number of Individuals Size of individuals Small Large Greyhounds Bred for speed

24. 3.Diversifying Selection Favorsopposite extremesFavors variants of opposite extremes. Number of Individuals Size of individuals Small Large

25. Speciation evolutionThe evolution of new species.

26. Reproductive Barriers mechanismimpedes fertile and/or viable hybrid offspringAny mechanism that impedes two species from producing fertile and/or viable hybrid offspring. Two barriers:Two barriers: 1.Pre-zygotic barriers prevent fertilization 2.Post-zygotic barriers prevents fertilized egg from developing into a fertile adult prevents fertilized egg from developing into a fertile adult

27. 1.Pre-zygotic Barriers a. Temporal isolation: Breeding occurs at different times for different species. b. Habitat isolation: Species breed in different habitats. c. Behavioral isolation: Little or no sexual attraction between species.

28. 1.Pre-zygotic Barriers d. Mechanical isolation: Structural differences prevent gamete exchange. e. Gametic isolation: Gametes die before uniting with gametes of other species, or gametes fail to unite.

29. 2.Post-zygotic Barriers a. Hybrid inviability: Hybrid zygotes fail to develop or fail to reach sexual maturity. b. Hybrid sterility: Hybrid fails to produce functional gametes. c. Hybrid breakdown: Offspring of hybrids are weak or infertile.

30. One oft-cited example of a postzygotic mating barrier occurs when horses and donkeys, two different species, interbreed to produce mules. Mules, as a hybrid offspring, are generally robust organisms. However, the genetic incompatibility of the horse and the donkey result in sterility in the mule. Because mules are infertile, gene flow between the horse and donkey is effectively blocked, even though they are able to produce hybrid offspring.

31. Natural Selection: differential success in reproduction; only form of microevolution that adapts a population to its environment Natural Selection: differential success in reproduction; only form of microevolution that adapts a population to its environment

32. Sexual selection Sexual dimorphism: secondary sex characteristic distinction Sexual dimorphism: secondary sex characteristic distinction Sexual selection: selection towards secondary sex characteristics that leads to sexual dimorphism Sexual selection: selection towards secondary sex characteristics that leads to sexual dimorphism Sexual dimorphism is a phenotypic difference between males and females of the same species. phenotypicspecies

33. Evolution of Populations Occurs when there is a change in relative frequency of alleles

39. Phenotype Expression Depends on how many genes control that trait Depends on how many genes control that trait

40. Single-Gene vs. Polygenic Traits Single-Gene: 2 Distinct Phenotypes Polygenic: Many Phenotypes (EG: tongue rolling)

41. Allele Frequencies Natural Selection Single Gene Traits Polygenic Traits Directional Selection Stabilizing Selection Disruptive Selection Genetic Drift

42. Natural Selection on Polygenic Traits Shifts to Shifts to middle range Shifts to Shifts to 2 extremes Shifts to Shifts to 1 extreme

44. Conditions needed for Genetic Equilibrium

45. Hardy-Weinberg Principle conceptshuffling of genes cannot changeThe concept that the shuffling of genes that occur during sexual reproduction, by itself, cannot change the overall genetic makeup of a population.

46. Hardy-Weinberg Principle principle fiveThis principle will be maintained in nature only if all five of the following conditions are met: 1.Very large population 2.Isolation from other populations 3.No net mutations 4.Random mating 5.No natural selection

47. Hardy-Weinberg Principle Remember:Remember: equilibrium If these conditions are met, the population is at equilibrium. “No Change” or “No Evolution”.This means “No Change” or “No Evolution”.

48. Macroevolution higher than the species levelThe origin of taxonomic groups higher than the species level.

49. Microevolution population’s gene poolA change in a population’s gene pool over a secession of generations. Evolutionary changes geological timeEvolutionary changes in species over relatively brief periods of geological time.

50. Five Mechanisms of Microevolution 1. Genetic drift: Change in the gene pool of a small population due to chance. Two examples:Two examples: a. Bottleneck effect b. Founder effect

51. SPECIATION THE FORMATION OF NEW SPECIES THE FORMATION OF NEW SPECIES AS NEW SPECIES EVOLVE, POPULATIONS BECOME REPRODUCTIVELY ISOLATED AS NEW SPECIES EVOLVE, POPULATIONS BECOME REPRODUCTIVELY ISOLATED REPRODUCTIVE ISOLATION – MEMEBERS OF 2 POPULATIONS CANNOT INTERBREED & PRODUCE FERTILE OFFSPRING. REPRODUCTIVE ISOLATION – MEMEBERS OF 2 POPULATIONS CANNOT INTERBREED & PRODUCE FERTILE OFFSPRING.

52. 3 ISOLATING MECHANISMS…….. BEHAVIORAL ISOLATION- CAPABLE OF BREEDING BUT HAVE DIFFERENCES IN COURTSHIP RITUALS (EX. MEADOWLARKS) BEHAVIORAL ISOLATION- CAPABLE OF BREEDING BUT HAVE DIFFERENCES IN COURTSHIP RITUALS (EX. MEADOWLARKS) GEOGRAPHICAL ISOLATION – SEPARATED BY GEOGRAPHIC BARRIERS LIKE RIVERS, MOUNTAINS, OR BODIES OF WATER (EX. SQUIRREL) GEOGRAPHICAL ISOLATION – SEPARATED BY GEOGRAPHIC BARRIERS LIKE RIVERS, MOUNTAINS, OR BODIES OF WATER (EX. SQUIRREL) TEMPORAL ISOLATION – 2 OR MORE SPECIES REPRODUCE AT DIFFERENT TIMES. TEMPORAL ISOLATION – 2 OR MORE SPECIES REPRODUCE AT DIFFERENT TIMES.

53. Table 23.1a

54. Tigon Result of male tiger and female lion mating incaptivity. Offspring are infertile. Separated both geographically and ecologically.

55. Liger Result of male lion and female tiger mating in captivity. Offspring are infertile.

59. Table 23.1b

60. Fig. 23.6 Four species of leopard frogs: differ in their mating calls. Hybrids are inviable.

61. Allopatric Speciation ancestral separatedgeographical barrier.Induced when the ancestral population becomes separated by a geographical barrier. Example:Example: Grand Canyon and ground squirrels

62. These squirrels live on opposite sides of the Grand Canyon. This is an example of allopatric speciation.

63. Hawaiian Honeycreepers FOUNDER SPECIES An example of adaptive radiation – these species all diverged from a common ancestor (founder species)

64. Adaptive Radiation Emergence of numerous species common ancestorEmergence of numerous species from a common ancestor introduced to new and diverse environments. Example:Example: Darwin’s Finches

65. SPECIATION IN DARWIN’S FINCHES SPECIAITON IN THE GALAPAGOS FINCHES OCCURRED BY: SPECIAITON IN THE GALAPAGOS FINCHES OCCURRED BY: - FOUNDING OF A NEW POPULATION, - GEOGRAPHIC ISOLATION which led to - - REPRODUCTIVE ISOLATION and CHANGES IN THE NEW POPULATION’S GENE POOL due to COMPETITION.

68. Evidence of Evolution 1. Fossil Record 2. Geographic Distribution of Living Species 3. Homologous Body structures 4. Similarities in Embryology

69. Evidence of Evolution Fossil Record provides evidence that living things have evolved Fossils show the history of life on earth and how different groups of organisms have changed over tim e

72. Convergent Evolution Speciesevolutionary branches very similar environments.Species from different evolutionary branches may come to resemble one another if they live in very similar environments. Example:Example: 1.Ostrich (Africa) and Emu (Australia). 2.Sidewinder (Mojave Desert) and Horned Viper (Middle East Desert)

73. Rat like common ancestor Mammalia Placental mammals Marsupial Mammals Sugar Glider Flying Squirrel Convergent Evolution and Analogous Structures

74. Review

75. Big Question!!!  How did life arise on the big blue planet??  Scientists attempt to answer this question scientifically.

76. Relative Dating versus Absolute Dating

77. Relative Dating Can determine a fossil’s relative age Can determine a fossil’s relative age Performed by estimating fossil age compared with that of other fossils Performed by estimating fossil age compared with that of other fossils Drawbacks – provides no info about age in years Drawbacks – provides no info about age in years

78. Absolute dating Can determine the absolute age in numbers Can determine the absolute age in numbers Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remain Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remain Drawbacks - part of the fossil is destroyed during the test Drawbacks - part of the fossil is destroyed during the test

79. Carbon-14 Dating

80. Fossil Formation

81.  A cosmic explosion that hurled matter and in all directions created the universe 10-20 billion years ago  Evidence  it explains why distant galaxies are traveling away from us at great speeds  Cosmic radiation from the explosion can be observed  The Big Bang theory probably will never be proven; consequentially, leaving a number of tough, unanswered questions. Big Bang Theory

82. What was early earth like?  Earth was Hot!!  Little or no oxygen  Gasses in atmosphere:  Hydrogen cyanide (poison to you!)  Hydrogen sulfide  Carbon dioxide  Carbon monoxide  Nitrogen  water

83. So how did the earth get oxygen?  Some of that oxygen was generated by photosynthetic cyanobacteria  Some came from the chemical separation of water molecules into oxygen and hydrogen.

84.  Oxygen drove some life forms to extinction  Others evolved ways of using oxygen for respiration

85. How did life begin? Miller and Urey’s Experiment  Passed sparks through a mixture of hydrogen methane ammonia and water  This produced amino acids – the building blocks of life

86. Miller’s experiment suggests that lightning could have produced amino acids

87. How can simple amino acids result in life? There are 3 theories 1. Formation of microspheres  Large organic molecules can sometimes form tiny proteinoid microspheres  Store and release energy, selectively permeable membranes, may have acquired more characteristics of living cells

88. 2 nd Hypothesis for Life Evolution of RNA to DNA RNA was assembled from simple organic molecules in a primordial soup RNA was assembled from simple organic molecules in a primordial soup RNA was able to replicate itself and eventually form DNA RNA was able to replicate itself and eventually form DNA Not scientifically proven to be possible Not scientifically proven to be possible

89. 3 rd Theory of Life Endosymbiotic theory  eukaryotic cells arose from living communities formed by prokaryotic organisms  Ancient prokaryotes entered primitive eukaryotic cells and remained there as organelles