def. The variety and variability of life-forms, both contemporary and extinct, including genetic and ecosystem diversity, in a defined area over time.

1. Levels of Biodiversity
   1. Habitat
   2. Genetic
   3. Species
2. Viewpoints on biodiversity
   1. Rivet popper
   2. Redundancy
3. Threats to biodiversity
   1. Natural loss
   2. Human Activity
4. Extinction

   Def. Failure of a taxonomic group to produce direct descendants, causing its worldwide disappearance from the record at a given point.

   1. Kinds
      1. background-natural
      2. Mass
         1. climate
         2. geologic
         3. meteorite
         4. human