10: Evolution

• Variation

  Differences in traits displayed by members of same species
• Desirable variations

  Incr chances of survival
• Undesirable variations

  Lead to a genetic defect
• What is the meiotic process known for?

  It serves as a source of variation
• What are the sources of variation in meiosis?

  1. Genetic recombination from crossing over
  2. Different chromosome combinations from independent assortment
  3. Fertilization of an egg by a sperm
  4. Mutations in germ cells
  5. Gene flow between populations
• What results from crossing over during gamete development?

  Genetic recombination
• How are different chromosome combinations formed in gametes?

  By independent assortment of chromosomes
• What occurs during fertilization?

  A sperm fuses with an egg
• What is a mutation in the context of gametes?

  A change in the germ cells forming gametes
• What is gene flow?

  Transfer of genes between populations
• How old is the Earth according to scientists?

  More than four billion years
• From what did new life forms develop?

  From unicellular organisms
• What does evolution refer to?

  Gradual alteration of traits over time
• How are evolutionary changes passed on?

  To the next generations
• How does evolution respond to environmental conditions?

  By altering a population's traits over time
• How does variation promote evolution?

  It allows some individuals to have more progeny
• What is an adaptation?

  An inherited trait that aids survival
• What do members of a species compete for?

  Resources such as food and water
• What determines which individuals survive and reproduce?

  Their health, fitness, and strength
• What is the first principle of natural selection?

  Overproduction of offspring
• Why do population sizes remain constant despite overproduction?

  Due to competition for scarce resources
• What is the third principle of natural selection?

  Variations among organisms
• What happens to organisms with desirable variations?

  They survive and reproduce successfully
• What is the outcome of natural selection over many generations?

  More advantageous genetic variations persist
• When did Charles Darwin propose the Theory of Natural Selection?

  In 1838
• What is the title of Darwin's book published in 1859?

  "On the Origin of Species by Natural Selection"
• What did Darwin observe about finch species in the Galapagos Islands?

  They varied in beak shape based on food
• How are speciation and adaptation linked according to Darwin?

  Adaptations lead to new species over time
• What are the three basic patterns in biological diversity identified by Darwin?

  Global, local, and variation over time
• What is the process of natural selection?

  • Organisms with helpful traits reproduce more
  • Increases genetic diversity in the population
  • Based on overproduction, competition, variations, and survival
• What are the implications of Darwin's observations on finches for evolution?

  • Beak shape varies with food source
  • Adaptations lead to speciation
  • Geographic isolation contributes to diversity
• What is evolution defined as?

  • Descent with modifications
  • Changes in inherited traits over generations
  • Driven by natural selection and adaptations