Two important questions in ecology are "How do we conserve ecosystems?" and "When we try to restore damaged ecosystems, what state do we restore them to?"

A discussion of camera traps and their use in ecological research.

The 2015 Holiday Lecture discussion session.

The fossil record contains evidence of five mass extinctions, when more than 75 percent of species went extinct. Mammals are a key group for comparing past and present extinction rates. Many living species are threatened, but there is still time to avoid a sixth mass extinction.

Human activities have caused the extinctions of many species in the past, and that is also happening today. Human population growth is driving habitat destruction and climate change, both direct threats to biodiversity.

The loss of biodiversity also means a loss of genetic diversity, which is the biological toolkit for adaptation. As populations of animals become increasingly isolated due to habitat fragmentation, assisted migration may be a strategy for preserving genetic diversity.

Ocean biodiversity is also threatened by human activities. But because the ocean is huge and has highly diverse environments, marine organisms appear to be more resilient than land animals when threatened by extinction and can bounce back with modest conservation efforts.

Coral reefs are threatened by many human activities, including global ocean warming from climate change. Some corals can survive unusually high temperatures by virtue of their genetic makeup. These heat-tolerant corals may hold the key to preserving coral reefs into the future.

The current threats to biodiversity are tightly coupled to human demand for power, food, and money. We can avoid a sixth mass extinction by rethinking how we use energy, how we feed the world, and the value we place on intact ecosystems.

A sixty minute discussion on biodiversity with the lecturers and students attending the 2014 Holiday Lectures. Moderated by HHMI vice president of Science Education, Dr. Sean Carroll.