Evolution

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Evolution

• Evolutionary change is based on interactions
  between populations of organisms and their
  environments

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Origin of the Species

• 1859 Darwin Published On The Origin of Species by
  Means of Natural Selection.
• A convincing case for evolution
• Evolution the process by which populations of
  organisms acquire and pass on novel traits from
  generation to generation

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2 points of Darwins book

• Species were not created in their present forms
  but evolved from common ancestors.
• Natural Selection is the mechanism for evolution

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Western culture resisted evolutionary views of
life

• Darwins view contrasted with the conventional
  paradigm of an 6000 year old Earth, and Universe
  made in 7 days
• Natural theology, Creationism, or Intelligent
  Design are all names for this point of view
• Others were laying groundwork for Darwins view.
  
• Talk of evolution for years before Darwin
  articulated a concise argument.

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Darwins Predecessors

• Economist Demographer Thomas Malthus 1798
  essay on Englands population noted that humans
  increase faster than food supplies.

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Darwins Predecessors

• Carolus Linnaeus
• Founder of Taxonomy
• Developed 2 part naming system
• Organized the diversity of life into groups
• But believed that God created all the life, he
  only organized it

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Darwins Predecessors

• Georges Cuvier developed Paleontology
• Documented where fossils were found in successive
  stratum of rock layers.
• Deeper the rock layer the older the life
• Also noted extinctions happened
• Yet opposed evolutionary theory
• In the view of Catastrophism the layers of
  fossils result because of flood or other
  disasters
• Extreme views of catastrophism hold that God
  wiped out all life and recreated it several times

Pittsburghs St. Patricks day flood of 1936,
water levels rose more than 40 feet.
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Geologists

• Charles Hutton came up with gradualism.
• Idea that erosion and continental drift slowly
  shape the Earth
• James Lyell came up with uniformitarianism
  geologic processes happen at a constant rate

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Darwins conclusions from Geology

• If geologic change is constant and slow, the
  Earth must be much older than 6000 years
• Slow, subtle processes over long periods can
  cause big changes in the Earth, so why not in
  populations of living things?
• Others were already saying this
• Underwater volcanoes slowly build into islands ?

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Galapagos
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Jean Baptiste Lamarck

• Saw lines of descent, how older fossils evolved
  into younger fossils
• Thought their were many ladders of descent
• Bacteria escalated into more complex life forms
• His problematic mechanism If a giraffe stretches
  its neck to get more food, then its kids will
  have stretched necks. Or if a blacksmith works
  out only his right arm, his children will have
  larger right arms.

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Darwins Field Research

• Born on 2/12/1809 (same as Lincoln) Darwin grows
  up, doesnt really have any direction, changes
  majors a couple of times.
• Just wants to go hunting and collect bugs
• Dads a big time doctor and getting fed up
• Sends him to medical school, Darwin drops it
• Darwin goes into the clergy, his mentor
  recommends him to be the on-board priest on the
  voyage of the Beagle

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On the voyage Darwin found an excellent
Megatherium Skull
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Darwin also discovered a new species of dolphin
which he named Delphinus Fitzroyi
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Voyage of the Beagle

• Captain of the Beagle Fitzroy ?, really
  religious, needs educated company so he recruits
  the young clergyman Darwin
• Bad Idea.
• Theyre the original odd couple
• Fitzroy 23y/old Creationist
• Darwin 22y/old Liberal Evolutionist
• Both sharing a cramped cabin filled with fossils,
  flora fauna samples Darwin collects when they
  go ashore
• Lots of fighting
• Years later Fitroy would literally bible thump
  while speaking against evolution.
• Much later Fitzroy slits his own throat, Darwin
  donated some to the widow.

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Beagle

• Goes around South America Galapagos for 5 years
• Darwin keeps bad records, who knows where this or
  that bird came from.
• Takes him six years after getting back to
  organize it all
• Sees unique adaptations of different species,
  notably Finches.

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Darwin focuses of adaptation

• New species arise as ancestral forms from the
  gradual accumulation of adaptations to different
  environments.
• Species fragment and get isolated
• Over a long time isolated population change
  enough that they become new species
• So Darwins famous for his adventure and has the
  idea for Evolution, then he does something weird

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He puts away his manuscript

• He doesnt publish for 14 years
• Has 10 kids, spends 8 years writing a book on
  barnacles, writes letters to Lyell, and a young
  naturalist named Alfred Wallace

• Why?
• Creationist criticism was rampant
• Darwin had a strange unidentified illness
• Maybe Chagas Disease caused by a Benchuca bug
  bite in South America
• Maybe Pscyhosomatic
• Maybe daddy issues

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1858 Wallace?

• Alfred Wallace sends Darwin a manuscript for his
  ideas on evolution.
• Darwin says Holy Crap! This Wallace kid is going
  to steal the show, Id better get moving.
• Publishes Origin of the Species. It sells out and
  everybody goes crazy with logic
• Wallace is cool, goes on to be a good thinker
  naturalist, but gets weird ideas about spirits
  and life on other planets

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• Darwin didnt call it evolution until the sixth
  printing of the book. He called it Descent with
  Modification
• Were all descended from some unknown ancestor
• Like an tree. Species at the leaves and the
  ancestor at the trunk. Closer related species
  share branches. Forks in branches are common
  ancestors
• Lots of dead ends 99 of species that have ever
  lived are extinct

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• The Linnean hierarchy of classification fit
  nicely with the branching genealogy of species
• Kingdomgtphylumgtclassgtordergtfamilygt
  genusgtspeciesgtsometimes race or breed
• Kids Playing Chicken On Freeways Get Smashed
• King Philip came over for good spaghetti

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Darwins Sweet Logic

• Observation 1 All species have such great
  potential fertility that population size would
  increase exponentially if all individuals born
  had maximum reproductive rates
• Observation 2 populations are stable
• Observation 3 Natural resources are limited

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• Inference 1 Production of more individuals than
  the environment can support leads to struggles
  for existence, and only a fraction survive.
• Observation 4 Individuals of a population vary
  in characteristics
• Observation 5 Much of this variation is
  heritable

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• Inference 2 Survival in the struggle for
  existance is not random, but depends in part on
  the hereditary constitution of surviving
  individuals. Those individuals whose
  characteristics fit them best to the environment
  are likely to leave more offspring than less fit
  individuals
• Inference 3 The unequal survival and
  reproductive ability will lead to a gradual
  change in a population with favorable
  characteristics accumulating over generations

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Natural selection

• Natural selection is the differential success in
  reproduction and its product is adaptation of
  populations of organisms to their environment.
• Though we didnt know it Mendels work published
  1868 explained this but no one recognized that
  for 30 years

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Evidence

• Artificial Selection We breed domesticated
  animals for certain traits. Humans modify
  species.
• Cauliflower, Cabbage, Brussels Sprouts, Broccoli,
  Kale, and Kohlrabi are all modified Wild Mustard

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Unintentional Artirficial Selection

• We dont always want things to adapt
• Drugs have evolved resistance to Antibiotics
• Pests have evolved resistance to pesticides

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Subtleties

• It takes a population to evolve, not an
  individual
• The best adaptations depend on place and time.
  Just because youve got a great mutation that
  lets you survive at -100 degrees it wont do you
  any good if you live in Brazil

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Evidence

• Biogeography Why are animals of South American
  tropics more closely related to South American
  deserts than African tropics? Why are most
  marsupials in Australia? Armidillos are only in
  America, fossils that look like Giant Armidillos
  are only in America.
• Go America!

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Biston moth

• industrial melanism - tree bark either light in
  color (covered with lichens) or dark in color
  (because of industrial soot). Light moths favored
  when most trees have lichens (no pollution) and
  dark moths favored when tree bark is dark from
  pollution.

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Fossil Record

• Biochem, Cell bio, and molecular bio all predict
  that prokaryotes should be the oldest organisms,
  and the oldest fossils are prokaryotes
• Stromatalite Blue Green Algae that trapped
  sediments and makes fossils that show evidence of
  biological activity, 500 -4500 million years old

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• Transitional evidence. A criticism of evolution
  by some. However a series of skulls exist in the
  strata that show the transition from reptiles to
  mammals.
• Also Archaeopteryx was found just in 1861
• Saltationists like T.H.Huxley (Darwins Bulldog)
  thought evolution happened suddenly
• What good is ½ an eye?
• Paleys argument from design likened it to
  finding a pocket watch, so complex it must have
  had an intelligent creator.

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• Comparitive anatomy the same skeletal elements
  make up the forelimbs of all mammals even though
  these appendages have different functions.
• Hands, paws, whale fins, bat wings, all have the
  same basic bones because they have a common
  ancestor. These bones are homologous structures
• Also why have vestigial organs? Some snakes have
  a simpilfied hip bone.

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Homologous as opposed to analagous structures
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Comparitive embryology

• Closely related organisms go through similar
  stages during development.
• All vertebrates go through a stage of development
  when they have gill slits.
• Ontogeny recapitulates Phylogeny
• The development of an individual replays the
  evolutionary history of the species

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Molecular Biology

• Similar DNA and proteins indicate a closer
  relationship.
• Who has the DNA most similar to yours?
• Weve got cytochrome C, a respiratory protein,
  and so do bacteria.
• There is a global common genetic code

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Is it just a theory?

• Depends on what you mean by theory.
• Theories are more than hypothesis. They account
  for many facts and explain a variety of
  phenomena.
• Its not Dogma. Evolution can be challenged, but
  youve got to come up for a better explanation
  for the evidence.
• You can debate gravity, but objects keep falling