Unit 5 AP Review (Evolution and Classification)

• Evolution


  Changes in a population or species
• Descent with modification

  Changes in allele frequencies over time
• Natural selection

  Cause of adaptive evolution
• Natural selection

  Results in evolution
• Individuals do not evolve, populations evolve
• Natural selection does not create new traits, but edits or selects for traits already present in the population
• There must be variation within the population
• Many offspring must be produced
• Selection

  For an inherited physical trait
• Nature


  Provides the variation of traits
• Nature

  Selects for "useful" traits
• Selective breeding

  Artificial Selection
• People

  Select for useful traits
• Fitness

  Reproductive success
• Adaptive Radiation

  The adaptation of an organism that enables them to spread successfully or radiate into other environments
• Scientists

  • Darwin
  • Hutton & Lyell
  • Lamarck
  • Malthus
  • Wallace
• Darwin

  • Diversity, Fossils -> different than current organisms
  • Common mainland ancestor -> survive and reproduce
  • Natural selection
  • Descent with modification explains life's unity and diversity
• Galapagos turtles and birds


  • Finches beak shapes evolved in response to the available food supply
• Hutton & Lyell

  Earth changes & is still changing by natural forces (wind, erosion, etc) over a extremely long period
• Lamarck

  • Use or lose theory
  • Organisms lose or use certain traits
  • Use -> acquired -> passed onto offspring (not accepted, epigenetics are a example of this rule though)
• Malthus

  • Babies born faster than people are dying
  • Organisms make many, many offspring
  • Resources are limited
  • Not all offspring can survive
  • Leads to insufficient resources
  • Predicts Natural selection
• Wallace


  • Independently figured out natural selection
• Variation, individuals no not evolve, population evolve
• Work on individuals and on phenotype
• Evidence of Evolution

  • Fossil Record
  • Homologous & Analogous Structures
  • Embryology
  • Vestigial Structures
  • DNA Homologies
• Fossil Record

  • Incomplete record
  • Different layers are formed and different times
  • Shows how species change over time & reveal extinct species
• Homologous Structures

  • Same basic structure
  • Different function
  • Indicates common ancestry
• Analogous Structures

  • Different Structure
  • Same Function
  • No common ancestor
• Embryology

  • Reveals similarities (for longer) in structure that are not evident in adults
  • Similarities may be lost later in development
  • Embryology indicates common ancestry
• Vestigial Structures

  • Structures reduced in size
  • Become functionless
  • Greater cost than benefit
• DNA Homologies

  • All life forms use DNA/RNA bases in DNA can be compared
  • Amino acid sequences in protein can be compared
  • Most accurate
  • No data on unique and extinct species
  • Variations will reduce differences between species
• Convergent Evolution


  • Same function
  • Different structures
  • No common ancestor
  • Analogous Structures
• Divergent Evolution

  • Different function
  • Same structures
  • Common Ancestor
  • Homologous Structures
• Biogeography


  • Species in discrete geographic acres are closely related to each other than species in distant geographic areas
  • Species more closely related by geography than simply by environment
• Sources of Genetic Variation

  • Mutations
  • Sexual Reproduction (Meiosis)
  • Crossing Over
  • Independent Assortment
  • Random Fertilization
  • Random mating
  • Polyploidy diploidy
• Mutations


  • Changes in nucleotide sequences
  • Only mutations in germ line cells are passed
• Sexual Reproduction (Meiosis)

  Creates individuals with new combinations of alleles
• Crossing Over

  • Non sister chromatids exchange DNA
  • Generates new combination of alleles
• Independent Assortment


  • Random orientation of homologous chromosomes on the metaphase plate
  • Each pole may receive either the maternal or the paternal homologous from each chromosome pair
  • The genes on different chromosomes assort independently into the gametes
• Random Fertilization

  • Zygote could contain any one of more than 70 trillion possible combinations of chromosomes
  • Causes variation