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evolution, speciation

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  1. 1. • Darwin’s Idea of Common Descent • Darwin’s Idea of Gradualism • Darwin’s Idea of Multiplication of Species • Darwin’s Idea of Natural Selection
  2. 2. Darwin’s Idea of COMMON DESCENT • evolution = descent with modification • All organisms are related through descent from some unknown ancestor that lived in the distant past. • As the descendants spilled into various habitats over time, they accumulated diverse modifications (adaptations) that fit them to specific ways of life. • The history of life is like a tree. • The Linnean classification scheme reflected the branching genealogy of the tree of life, with organisms at the different levels related through descent from common ancestors.
  3. 3. The evolutionary history of organisms can be portrayed as a tree growing through time.
  4. 4. Genealogy of the primates
  5. 5. Darwin’s Idea of GRADUALISM • The origin of new species and adaptation are closely related processes. • A new species would arise from an ancestral form by the gradual accumulation of adaptations to a different environment. • e.g. Darwin’s finches  ADAPTIVE RADIATION large ground finch small tree finch woodpecker finch
  6. 6. Darwin’s Idea of MULTIPLICATION of SPECIES  The existence of an enormous number of species  some species are very similar (not as distinct from each other!)  gradual changes in various characteristics as organisms became modified according to the conditions in which they lived
  7. 7. Darwin’s Idea of NATURAL SELECTION as the Mechanism for Evolution • Overproduction - All species have a tendency and the potential to increase at a geometric rate. 2. Competition - The conditions supporting life are limited. - Only a fraction of the offspring in a population will live to produce offspring, so that the number of individuals in a population remains fairly constant.  The environments of most organisms have been in constant change throughout geologic time.
  8. 8. 3. Variation - Individuals in a population vary greatly in their characteristics. 4. Adaptation - Some variations enable individuals to produce more offspring than other individuals. 5. Natural Selection - Individuals having favorable traits will produce more offspring, and those with unfavorable traits will produce fewer offspring. • Speciation - Given time, natural selection leads to the accumulation of changes that differentiate groups from one another, such that a new species may arise.
  9. 9. Industrial Melanism: The Peppered Moth (Bis to n be tula ria )
  10. 10.  Natural Selection  Survival of the Fittest Other examples: 1. Insecticide resistance 2. Drug resistance in bacteria  A population is the smallest unit that can evolve.  Natural selection acts on individuals, but individuals do not evolve.  Natural vs. Artificial Selection Camouflage as an example of evolutionary adaptation
  11. 11.  Divergent evolution – from one species to several different forms; adaptive radiation  Convergent evolution – results in increased resemblance between unrelated species  Coevolution – occurs when two or more species evolve in response to each other
  12. 12.  Biological diversity is the product of evolution.  The mechanism of modification has been natural selection working continuously over long periods of time.
  13. 13. At the time, Darwin did not understand the genetic basis for evolution.  Variations arise from mutation and genetic recombination.  Much of the variation observed in the individuals of a population is heritable.
  14. 14.  Variation mostly occurs as a result of gene mutations and genetic recombination.  Evolution is the change in allele frequency within a population over time. gene allele frequency gene pool Ernst Mayr
  15. 15. The Processes
  16. 16.   Evolution involves populations, not Individuals Species is a population of organisms whose members can interbreed under natural circumstances and reproduce fertile (viable) offspring
  17. 17.       Two fundamental processes give rise to new species: Cladogenesis: The splitting off of one species into two clades, usually because of geographical isolation, but also because of reproductive isolation. Two kinds of species develop by cladogenesis: Sympatric Species: Those whose speciation is the product of geographical isolation Allopatric Species: Those whose speciation is the product of reproductive isolation of population in the same region. Anagenesis: The replacement of an ancestral species by a daughter species over time; the ancestral species become extinct.
  18. 18.        Cladogenesis: Time I: Genes flow freely in region Time II: Barrier separates two populations Time III: Mutations change genotype and phenotype of 2 populations Time IV: Two populations cannot interbreed even with removal of barrier Definition: Branching of one species into two From clade (“branch”) or group with common evolutionary ancestry.
  19. 19.   Allopatric speciation occurs when two populations are separated by a geographical barrier (river, mountain range) In this example, three species of fish have evolved in separate zones
  20. 20.    Sympatric species are those that are separated by a reproductively isolation mechanism Speciation occurs among three populations of fish even though the different species occupy the same region There are several ways for subspecies to become reproductively isolated
  21. 21.       Ecological Isolation: Different populations are separated by occupy a slightly different niche Seasonal Isolation: The breeding season of two closely related populations do not match. Sexual Isolation: One or both sexes of a species initiate mating behavior that does not act a stimulus to the opposite sex of a closely related population Mechanical isolation: Populations do not mate because of an incompatibility of the male and female sex organs of the individuals (extreme example: wolves and Chihuahuas) Gamete Isolation: Incompatibility of sex cell with bodily environment Hybrid Infertility or Sterility: Hybrids do not survive or reproduce (mules)
  22. 22.       Micromutation: Mutations with extensive or important phenotypic results Example: Axolotl (species of salamander) This salamander starts life as tadpole-like larvae, as do other salamanders Axolotl, however, never grows up —doesn’t sprout mature legs, keeps its gills, remains aquatic existence. Injection of a hormone enables maturity and to live on land, so that one mutation can and does create major change
  23. 23.     Definition: Evolution and spreading out of related species into new niches Niche: An environment in which an organism is found and its adaptive response to that environment Generalized Adaptive Radiation: The adaptation of a species to a wide range of niches. Homo sapiens is an example. Specialized Adaptive Radiation: The adaptation of a species to a narrow range of niches.
  24. 24.    Absence of similar and therefore competing species Occurrence of extensive extinction, thereby emptying an environment of competitors Adaptive generalization of new group of related species which enable it to occupy several niches and displace species already there.
  25. 25.     Example: Darwin’s finches on Galápagos Islands who were blown there by winds from mainland Ecuador Niches opened up for 13 varieties with different bills, including those that feed on cactus or eat specific insects in trees Others use twig or cactus spine to probe for insects A vampire finch sucks blood from larger birds
  26. 26.    Ground finches (Geospiza) who are seed and cactus eaters; Tree finches (Camarhynchus), who are insect and bud eaters Warbler finches (Certhidea) who vary by color.
  27. 27.      Definition: Adaptation of a species to a narrow range of environmental niches Example: Again, some species of Darwin’s finches on Galápagos Islands are examples. Medium ground finch was nearly wiped out in the 1977 drought Sudden change could eliminate this or others of these genera and species of finches Example: prosimians adapt on in habitats afforded by Madagascar and are close to extinction.
  28. 28.      Definition: Adaptation of a species to a wide range of environmental niches Examples: Mammals spread after the disappearance of dinosaurs 65 m.y.a. and occupied innumerable niches, from grassland (ungulates) to trees (bats) Monkeys with a mixed diet occupied diverse arboreal (tree) habitats; they displaced the prosimians Humans: from frozen north to tropical rainforest or desert—thanks to culture—are the most generalized primate
  29. 29.      Definition: Slow, step-by-step changes over time Intermediate forms assume “missing links” Darwin postulated this model Examples: From monkeys to apes; apes to hominins (e.g. Lucy); and from early hominins to modern Homo sapiens
  30. 30.      Fossil record does not reveal fine gradations from one lifeform to a descendant life form: no “missing links.” Bipedalism occurred quickly as the fragmentary fossil record shows. Reproductive advantage: do slight changes bestow this advantage? Continuum question: at which point does a population become two species? Sometimes, change can take place rapidly, either through oscillating selection or punctuated equilibrium
  31. 31.       Definition: Adaptive variation around a norm rather than direction in response to environmental variation Example: Medium and small ground finch lacked a bill strong enough to crack tough seeds Occurrence of drought selected plants whose seeds had a tough exterior Survival of large, longer-billed finches Smaller, shorter-billed finches returned after the climate returned to normal, Shifting bill size and lengths reflected the oscillation of the environmental conditions.
  32. 32.     Definition: Species tend to remain stable over time, then, evolutionary changes occur suddenly (in terms of centuries or millennia) Causation: Populations may become fragmented and isolated, and from there new forms arise Small, new populations may invade a region, and through the founder effect and better adaptation, create and spread a new species Example: Archaeopteryx (ancient bird), a dinosaur with feathers: suddenly appears and may have created a new class known as Aves (birds)
  33. 33.  A summary of gradualism and punctuated equilibrium
  34. 34.    Pseudoscience consists of scientifically testable ideas in form that are taken on faith even after they are proven as false (Scientific) Creationism is the belief in a literal biblical interpretation of the creation of earth in six days 6,000 to 10,000 years ago The claim is testable, has been tested, and has been demonstrated to be false.
  35. 35.     Existence of strata, such as the Grand Canyon, accumulated over 2 billion years falsifies the claim that the earth is only a few thousand years old Presence of extinct lifeforms, from fossil fish to dinosaurs, demonstrate that other forms existed at one time but are now extinct Presence of ancient hominins establish extinct humanlike creatures that look like us but are not us. Both kinds of evidence are abundant
  36. 36.       Species is unit of evolution Evolutionary change is more random than progressive Speciation is the basic process of evolutionary change Changes may be gradual or rapid Scientific rule: follow the evidence Evidence for evolution is overwhelming in the form of geological strata and fossil lifeforms
  37. 37. Mike Riddle Answers in Genesis
  38. 38.   A history of apemen – the track record Two case studies 1. Neandertals 2. Australopithecines and Lucy  How evolution hinders critical thinking  How things change
  39. 39. The Bible teaches that Evolution begins with the assumption that God created man man has evolved from ape-like creatures So God created man in his own image, in the image of God created he him; male and female Genesis 1:27 Pick your relative
  40. 40. Holt, Rinehart, & Winston, Biology – Visualizing Life, 1998, p. 213. “Look closely at your hand. You have five flexible fingers. Animals with five flexible fingers are called primates. Monkeys, apes, and humans are examples of primates….Primates most likely evolved from small, insect-eating rodentlike mammals that lived about 60 million years ago.”
  41. 41. Miller and Levine, Biology, 2000, p. 757. “But all researchers agree on certain basic facts. We know, for example, that humans evolved from ancestors we share with other living primates such as chimpanzees and apes.”
  42. 42. Segment of lower ape-like jaw Segment of human skull
  43. 43. New York Times ran an article: “Darwin Theory Proved True.”   Featured in textbooks and encyclopedias In 1953 scientists studied the bones The Truth A fraud (600 year old bones)
  44. 44.    1922 fossil evidence was discovered Used to support evolution in the 1925 Scopes trial The claim: 1 million year old intermediate link The Truth An extinct pig’s tooth
  45. 45. 1930s What they found What they drew
  46. 46. Time Magazine (Nov. 7, 1977) “Ramapithicus is ideally structured to be an ancestor of hominids. If he isn't, we don't have anything else that is.”
  47. 47. The claim: 14 million year old intermediate between ape-like creatures and humans The truth  In 1970 a baboon living in Ethiopia was discovered. Same dental structure  Similar morphological features found on Ramapithecus   Ramapithecus dropped from human line
  48. 48.    Piltdown Man ……… Hoax Nebraska Man …….. Pig Ramapithecus …….. Ape What about the dates? In each case the date (age) was completely WRONG!
  49. 49. Neandertals Lucy and the Australopithicines
  50. 50. Original Drawing of Neandertal
  51. 51.    First found near Dusseldorf, Germany in 1856 Constructed to look ape-like Brain capacity about 200 cc larger Initial construction discovered to be wrong      Used jewelry Used musical instruments Did cave paintings Capable of speech Buried their dead
  52. 52. Marvin Lubenow, “Recovery of Neanderthal mtDNA: An Evaluation,” Creation Ex Nihilo Technical Journal, 1998 p.89. “Most anthropologists recognize burial as a very human, and a very religious, act. But the strongest evidence that Neandertals were fully human and of our species is that at four sites Neandertals and modern humans were buried together.”
  53. 53. From Buried Alive by Dr. Jack Cuozzo Drawing of a Neandertal fossil purchased at the souvenir counter at the museum in Berlin giving an apelike appearance Lower jaw 30 mm (over an inch) out of the socket
  54. 54. From Buried Alive by Dr. Jack Cuozzo Flat, human appearance Lower jaw 30 mm (over an inch) out of the socket
  55. 55. Thick brow Stocky body build Short extremities
  56. 56.  Common dates for Neandertals are 130,000 to 30,000 years ago  Neandertals existed for about 100,000 years (2,500 generations)
  57. 57. 2000 1 6 billion 300 million 100 generations Where are the fossils? There should have been over 50 billion Neandertals that lived during this time!
  58. 58.   1964: Neanderthals are a sub-species of humans 1997: Neanderthals are a separate species (based on mtDNA find) Luigi Cavalli-Sforza (Professor of genetics Stanford University), Genes, People, and Languages, 2000, p. 35. “The results of mitochondrial DNA show clearly that Neandertal was not our direct ancestor, unlike earlier hypotheses made by some paleoanthropologists.”
  59. 59. How was this comparison made? 1,669 modern humans were compared with one Neanderthal
  60. 60.   When compared to modern humans there were 22 mtDNA substitution differences Between modern humans the range is from 1 to 24 mtDNA differences Neanderthal and human Human and human What does this mean?
  61. 61.  There are a few modern humans who differ by 2 substitutions more than the Neanderthal individual  Therefore, using evolutionists logic, these people are a separate species (not human) ~ 8% of the people here tonight are not human
  62. 62.      Protruding brow ridge Stocky body build and short extremities Isolated population of people Lived in a cold, harsh climate 100% human Neandertal man, reconstructed from a skull found in La Chapelle-aux-Saints, France
  63. 63. A Case Study in Deception Lucy and the Australopithecines
  64. 64.   What was found Did Lucy walk upright Note: Lucy is our ancestor
  65. 65. Artistic conception Australopithecus africanus What do you notice about this picture? Note contemplative gaze, human hands and use of tools.
  66. 66. John Gurche, artist, National Geographic, March, 1996 p. 109. “I wanted to get a human soul into this ape-like face, to indicate something about where he was headed.”
  67. 67.     Lucy discovered in 1974 About 40% of the fossil was found Claimed to be 3.5 million years old Claimed bipedal (walked upright)
  68. 68.          No similarity in appearance to humans Long arms are identical to chimpanzees Jaws are similar to chimpanzees Upper leg bone is similar to chimpanzees Lucy’s legs were very ape-like Brain size (400-500 cc) overlaps chimpanzees Large back muscles for tree dwelling Hands similar to pygmy chimpanzee Feet were long and curved
  69. 69. To determine if Lucy walked upright three areas of anatomy were examined 1. The rib cage 2. The pelvis 3. Leg and foot bones
  70. 70.   Ape ribs are conical shaped Human ribs are barrel-like Human Circular barrel-like Ape Conical shape
  71. 71. Peter Schmid (paleontologist at the Anthropological Institute in Zurich) Quoted from Origins reconsidered: In Search of What Makes Us Human by Richard Leakey and Roger Lewin “I noticed that the ribs were more round in crosssection, more like what you see in apes. Human ribs are flatter in cross-section. But the shape of the rib cage itself was the biggest surprise of all. The human rib cage is barrel shaped, and I just couldn’t get Lucy’s ribs to fit this kind of shape.”
  72. 72. Brad Harrub (Ph.D. Anatomy and Neurobiology) and Bert Thompson (Ph.D. Microbiology), The Truth About Human Origins, 2003, p. 47. “In Lucy’s case, her ribs are conical, like those found in apes.”
  73. 73. Chimp Human
  74. 74. J. Stern & R. Sussman, American Journal of Physical Anthropology, 1983, pp. 291 & 292. “The fact that the anterior portion of the iliac blade faces laterally in humans but not in chimpanzees is obvious. The marked resemblance of AL 288-1 (Lucy) to the chimpanzee is equally obvious… It suggests to us that the mechanism of lateral pelvic balance during bipedalism was closer to that in apes than in humans.”
  75. 75. Lucy’s pelvis is “wrong” because it is very ape-like PBS Nova Series; In Search of Human Origins episode one 1994 (Dr. Owen Lovejoy)
  76. 76. PBS Nova Series; In Search of Human Origins episode one 1994 (Dr. Owen Lovejoy)
  77. 77. 15° carrying angle (valgus) Human = 9° Gorilla = 0° Chimp = 0° Orangutan = 9° Spider monkey = 9°
  78. 78. • • •