1. Extinction… is a natural process by which some branches (lineages) of the tree of life are pruned away.

2.  Diversity of life on Earth has been impacted by both evolution and extinction over millions of years.  “Natural” factors such as major climactic change can cause extinction.  One theory holds that there have been 5 mass extinctions another states 7 of them.  Diversity of life on Earth has been impacted by both evolution and extinction over millions of years.  “Natural” factors such as major climactic change can cause extinction.  One theory holds that there have been 5 mass extinctions another states 7 of them.

3. Mass Extinction Events  Major increase in the amount of extinction (i.e., lineage termination).  Occurs over a relatively short period of time geologically speaking.  Results in at least a temporary decline in diversity (numbers/kinds of species)  Ex. K-T extinction associated with massive die off of the dinosaurs.  Major increase in the amount of extinction (i.e., lineage termination).  Occurs over a relatively short period of time geologically speaking.  Results in at least a temporary decline in diversity (numbers/kinds of species)  Ex. K-T extinction associated with massive die off of the dinosaurs.

4.  It is important to understand the nature and consequences of human mediated extinctions. - recall from the video… “humans might be the next great asteroid” - Humans have the capacity to cause large scale extinctions by disrupting and altering the biosphere.  It is important to understand the nature and consequences of human mediated extinctions. - recall from the video… “humans might be the next great asteroid” - Humans have the capacity to cause large scale extinctions by disrupting and altering the biosphere.

5.  Many scientists believe we are in the midst of a sixth major extinction event.  “Sixth extinction” differs from prior mass extinctions in important ways.  Increased rate (speed) at which species are being lost (100X greater than what is seen in the fossil record)  Greater diversity (number and kinds of species) are being lost.  Appears to be caused by humans.  Many scientists believe we are in the midst of a sixth major extinction event.  “Sixth extinction” differs from prior mass extinctions in important ways.  Increased rate (speed) at which species are being lost (100X greater than what is seen in the fossil record)  Greater diversity (number and kinds of species) are being lost.  Appears to be caused by humans.

6. Human Effects  Destruction of habitat.  Pollution  Over-exploitation of natural resources  Human overpopulation  Spread of agriculture  Destruction of habitat.  Pollution  Over-exploitation of natural resources  Human overpopulation  Spread of agriculture