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Paul Andersen details the evolutionary processes of speciation and extinction. Stickleback evolution in Lake Loberg is used as example of rapid speciation. Adaptive radiation is illustrated using the Hawaiian honeycreeper. A brief discussion of extinctions and mass extinctions is also included.

Hank takes us on a trip through time to revisit the 5 major mass extinction events that have impacted species over the Earth's history, and leaves us with some thoughts about what could possibly be the sixth event - the one caused by human activities.

A team of scientists, in a groundbreaking analysis of data from hundreds of sources, has concluded that humans are on the verge of causing unprecedented damage to the oceans and the animals living in them. "We may be sitting on a precipice of a major extinction event," said Douglas J. McCauley, an ecologist at the University of California, Santa Barbara, and an author of the new research, which was published on Thursday in the journal Science.

Are we witnessing a sixth mass extinction? What factors threaten ecosystems on land and in the sea? What are researchers doing to try to conserve biodiversity and ecosystems such as tigers in Asia and coral reefs around the world? What tools do we have to avoid a global catastrophe? In six half-hour lectures, three leading scientists describe the state of biodiversity on our planet and how to face the great challenges that lie ahead.