Evolution

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Evolution

• Bio I
• Rupp

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Focusing Questions

• What is Evolution?
• Who was Darwin and why is he so important to
  biology?
• Who are the men that influenced Darwins
  thinking?
• What are the three main parts of Darwins theory?
• What evidence is there for evolution?

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Formation of the Earth

• Roughly 5 billion years ago
• Dust and debris collapsed inward on itself
• Colliding debris formed planets

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Age of the Earth

• Approximately 4.6 billion years old
• Radioactive dating of core samples

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Alexander Oparin

• Russian scientist
• Theory of early Earth
• Ammonia
• Hydrogen gas
• Water vapor and random organic chemicals
• 1923

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Miller and Urey

• Modeled Oparins theory in the lab
• Set up a closed system that contained ammonia,
  hydrogen, and water
• Electrodes simulated lightning
• Experiments completed in 1953

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Sidney Fox and his microspheres
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Why is Life so Diverse?

• The answer is Evolution, but what is Evolution?
• CHANGE OVER TIME!!!!!!
• It is a theory
• Well supported explanation
• There is abundant evidence

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Who was Darwin?

• Born on Feb. 12 1809
• Not a great student, but good at observing life
• Collected beetles
• After college received a job as a dinner
  companion on a boat

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Voyage of the H.M.S. Beagle

• The Beagle began her voyage in 1831
• Supposed to be a 2 year voyage, it lasted 5 years
• Darwin acted as the ships naturalist and
  collected many specimens

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Darwins Observations

• Impressed by how well adapted organisms were to
  their environment.
• Noticed that grasslands in different areas had
  different species. Why wouldnt all grasslands
  have the same species???
• Collected many fossils, the preserved remains of
  an extinct organism, and noticed that fossils
  resembled modern day organisms.

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Fossils and Modern Day Organisms

• Glyptodont

• Armadillo

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Fossils and Modern Day Organisms

• Giant Ground Sloth

• Three-toed Sloth

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The Galapagos Islands

• Very different climates from island to island
• Small, low islands were dry without much
  vegetation
• Large, tall islands received rainfall and were
  lush with vegetation

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The Galapagos Islands

• Based on the island habitat the animals would be
  different
• The best example is the tortoises

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• Isabela Island tortoise

• Hood Island Tortoise

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Why would the tortoises be different from island
to island?

• Habitat changes!!!!!!!

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Darwins Finches

• Birds differed from island to island also
• The beaks were specially designed to each island
  to feed on whatever food was available

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Shaping Darwins Thinking

• James Hutton

• Charles Lyell

• His work was based in geology
• Stated that changes in rocks and Earth occur
  slowly
• Mountains are pushed up
• Mountains can be buried
• TIME!!!!

• Also dealt with geology
• Stated that processes we can see today probably
  also occurred in the past
• Again these changes took time
• TIME!!!!

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James Hutton
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Charles Lyell
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Shaping Darwins Thinking

• Jean-Baptiste Lamarck

• Thomas Malthus

• Naturalist
• Lamarck developed his own evolution theory with
  three parts
• Tendency towards perfection
• Theory of use-disuse
• Inheritance of acquired traits
• It was a bad theory

• Economist
• If human population increased then there would
  soon be insufficient space and food
• Could this be true for other species
• Struggle to survive

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Jean-Baptiste Lamarck
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Thomas Malthus
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On the Origin of the Species Darwins Book

• Published in 1859
• Showcased Darwins theory of Natural Selection
• Began the book with easily understood concepts
• Natural variationdifferences among individuals
  of a species
• Artificial selectiontraits selected by humans in
  breeding animalsdog breeds as an example

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Natural Selection

• There is a struggle for existence and those
  organisms better suited to the environment win
  the struggle and pass on their genes
• It is otherwise known as survival of the fittest

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Descent with Modification

• Natural selection and natural variation produces
  organisms slightly different than their parents
• Over time these differences add up to change or
  modifications
• If you go back far enough in time you will find a
  common ancestor
• Common descentall organisms came from the common
  ancestor

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Evidence of Evolution

• Homologous body structures

• Vestigial organs

• Similarity in limbs
• Shows common descent

• Limbs that are reduced in size
• Previously had a function
• Appendix, tonsils, and tailbone

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Homologous structures
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Vestigial structure
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Evidence of Evolution

• Fossil record

• Geographic distribution

• Showed what organisms used to look like versus
  todays organisms
• Detailed history of change

• Different organisms in different areas share
  similarities
• The differences are due to changes caused by the
  habitat

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Geographic distribution
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Evidence of Evolution

• Similarities in early development

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Darwins Conclusions/Summary

• Organisms differ from one to another
• Organisms produce more offspring than can survive
• Organisms must compete for resources
• The uniqueness of organisms gives them advantages
  and disadvantages in competition

• Individuals best suited to their environment
  survive and reproduce and pass on their traits
• Changes in traits causes changes in species over
  time
• Species alive today descended with modifications
  from a common ancestor
• All organisms on Earth emerged from a single tree
  of life

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Focusing Questions

• What is Evolution?
• Who was Darwin and why is he so important to
  biology?
• Who are the men that influenced Darwins
  thinking?
• What are the three main parts of Darwins theory?
• What evidence is there for evolution?