Biological change over time

• Before technology was available to show otherwise, the thought that Earth's natural surroundings changed was unimaginable and life forms were thought to be immutable (unchanged and unchanging)
• By the 19th century, there was sufficient evidence that Earth was very old (billions of years) and that life forms on Earth had undergone and continued to undergo changes
• Mutations


  Changes in genetic information, the original sources of genetic variation
• Types of mutations


  • Neutral
  • Harmful
  • Beneficial
• Neutral mutations


  Provide no benefit or harm to the individual
• Harmful mutations


  Reduce the reproductive success of an organism
• Harmful mutations


  • Cystic Fibrosis
  • Huntington's Disease
• Beneficial mutations


  Produce a change in an individual's phenotype that gives the individual an advantage
• Beneficial mutations


  • The sickle cell allele gives carriers a high degree of resistance to malaria
  • Changes as a result of human manipulation
• Artificial selection


  Directed breeding in which individuals that exhibit a particular trait are chosen as parents of the next generation, used to produce new breeds or varieties of plants/animals
• Limitations of artificial selection

  • Breeders cannot create traits that do not already exist in some form within the population
  • If mutations arise, then breeders have new material to work with
• In the past, Evolution was not accepted within the Catholic religion
• With newer Popes, evolution has become accepted because they recognize that the Book of Genesis, and creation of all life in 7 days had to happen gradually over time