Evolution
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Evolution

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Evolution Evolution Presentation Transcript

  • Evolution
  • What is Evolution?
    • Evolution - how modern day organisms have changed from ancient organisms.
    • - gradual “change over time”
  • Charles Darwin
    • Collected data and observations to create hypothesis about evolution.
    • Published On the Origin of Species containing his theory of evolution .
  • Darwin’s Observations
    • He visited many continents while serving on the ship H.M.S Beagle.
    • He noticed a great diversity (variety) in organisms (species) on these different continents .
    • Australia – Kangaroos
    • Galapagos – Giant Tortoises and Finches
  • Species
    • Species – a group of organisms that can reproduce and create offspring that can reproduce.
  • Who Survives?
    • Natural Selection – those individuals who have favorable variations (from their genes) are able to survive and reproduce successfully.
  • Conditions for Natural Selection
    • Overproduction – every species produces more individuals than will survive.
    • Ex: insects, fish, dandelions
    • 2. Struggle for Survival – individuals within a species will compete for resources.
    • - Ex: environmental conditions: food, space, water, etc.
    • 3. Adaptation (adaptive value) – any genetic trait that helps an organism survive, compete, and reproduce better than others.
    • - Ex: Grasshoppers with longer legs
    • Lions with sharper teeth
  • Where Do Variations Come From?
    • Genetic variations can only be passed on if they occur in gamete cells .
    • Sources of variation:
    • a. Mutation – change in DNA bases.
    • - Some are “good” and can be passed on .
    • b. Sexual Reproduction – crossing over of chromosomes and sexual recombination (fertilization) increases variety in offspring.
    • Mutations occur at random – “good” ones will become popular and passed on.
    • Survival of the Fittest – individuals who have certain variations will be able to survive if environment changes.
    • - Ex: Disease and resistance/immunity
    • 5. Speciation – those individuals that survived to reproduce, may develop into a new species.
    • How does it happen?
    • Reproductive isolation – a population may become separated by a geographical barrier.
    • - Ex: River, mountain range, earthquake, ocean
    • Many new species of finches develop from isolation.
    • Differences in beak sizes/shapes result from different environments (food sources).
  • Examples of Natural Selection
    • Peppered Moth Evolution
    • Change in moth color from white to black due to change in their environment from white to black.
    • Black moth color = “favorable” mutation
    • Antibiotic Resistance
    • Antibiotics – kill bacteria with diseases.
    • Through natural selection, some bacteria mutate and become resistant (not affected) to antibiotics .
    • These resistant bacteria multiply (asexually) and soon become the only bacteria around.
    • New antibiotics must now be made.
    • http://www.pbs.org/wgbh/evolution/library/10/4/l_104_03.html
  • Red Bacteria have mutation for resistance After Treated with Antibiotic Only Red Bacteria survive and pass on good mutation
  • Evidence of Evolution
    • Similarities in DNA and Proteins
    • Proteins from 2 different species may have similar amino acid sequences.
    • - Ex: Humans and Chimpanzees share same protein for blood which differs by only 1-2 amino acids.
    • 2. Similarities in Embryo Development
    • Early stages of embryos in many animals is very similar.
    • - Differentiation happens the same way in many organisms.
    • - Suggests we come from a common ancestor .
    • 3. Homologous Body Structures
    • Similarities in forelimb bones of different animal species: wing of a bat, flipper of a whale, arm of a human.
    • - Bones are attached in similar places  all came from a common ancestor .
    • Vestigial structures – organs that serve no function in an organism.
    • - may have been useful in the past.
    • - Ex: human appendix, leg bones in whale
    • 4. Fossil Record – fossils from different layers of the earth show species have changed over time.
    • - The earth is approximately 4.7 billion years old .
  • Origin of Life
    • First organisms were single-celled (bacteria).
    • As time went on, more complex multicellular organisms developed.
    • Now, the most complex multicellular organisms (humans) have evolved.
  • Extinction
    • Extinction - Disappearance of species from the earth.
    • - Species cannot adapt to changing environment .
    • - Natural disaster (meteor)
  • - Bottom layers= oldest (simplest) - Top layers = most recent (more complex)
  • Phylogenetic (Family) Trees
    • Family Tree - Simple diagram used to show relationships and common ancestors amongst species.
  • A B C D F E G Past Present E is a common ancestor to both B and C! Family Tree
  •  
  • Punctuated Equilibrium
    • Punctuated Equilibrium – long, stable periods of equilibrium interrupted by rapid change (due to mutations).
    • - Different speeds of evolution for different species.