What is biodiversity?

Biodiversity is the extraordinary variety of living creatures and ecological communities growing and interacting with each other all over the world. It is the richness and complexity of species and ecosystems throughout the planet - continually acquiring and honing the adaptations necessary for survival under constantly changing conditions.

Earth is home to an estimated 10 to 20 million species, but only a fraction are known and scientifically classified. The interdependence among organisms and their environments creates and sustains the conditions needed for survival by all living creatures.

Biodiversity is disappearing at an alarming rate, at levels from genes and species to ecological communities. Some ecologists predict that 50 per cent of all mammals and birds will be extinct within the next century. Biologists believe the loss of these resources threaten the functioning of natural systems and the overall well-being of human society.

The United Nations' "Millenium Ecosystem Assessment" is the most comprehensive evaluation of human impacts on biodiversity. It also examines the dangers that that environmental damage poses to human society. Hundreds of the world's leading scientists contributed to this project - including David Suzuki,who is actively involved as a board member.

Counting Earth's species

It's difficult to count the number of Earth's species, so scientists use rigorous estimation methods. So far, about 1.75 million species have been officially classified. But this number will increase as new species are discovered. We may never know the full range of nature's diversity as some organisms (bacteria, nematode worms) may be undercounted while some habitats (tree canopies, the deep ocean) are still largely unexplored.

According to the federal government's Canadian Biodiversity Information Network (CBIN), there are 71,000 species of plants and animals in Canada, and at least as many still undiscovered.

Types of biological diversity

Three different types of biological diversity coexist and create complex interactions. Each ecosystem and organism has different functions in the web of life:

Community or ecological biodiversity refers to the variety of ecological communities that exist.

Genetic biodiversity refers to the range of individual variation within a single species. This can be seen in the killer whales that live off the west coast of British Columbia. Some pods survive by eating marine mammals while others feed exclusively on fish. This is an example of the different survival strategies used by a single species.

Species biodiversity is the kind of biodiversity that we usually think of, and it includes different types of species from bacteria to beluga whales, and plankton to palm trees.