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What is Biodiversity?

Short for biological diversity, biodiversity includes all organisms, species, and populations; the genetic variation among these; and all their complex assemblages of communities and ecosystems. It also refers to the interrelatedness of genes, species, and ecosystems and their interactions with the environment. Usually three levels of biodiversity are discussed—genetic, species, and ecosystem diversity.

Genetic diversity is all the different genes contained in all individual plants, animals, fungi, and microorganisms. It occurs within a species as well as between species.

Species diversity is all the differences within and between populations of species, as well as between different species.

Ecosystem diversity is all the different habitats, biological communities, and ecological processes, as well as variation within individual ecosystems.

What are the Threats to Biodiversity?

The loss of biodiversity is a significant issue for scientists and policy-makers and the topic is finding its way into living rooms and classrooms. Species are becoming extinct at the fastest rate known in geological history and most of these extinctions have been tied to human activity.

Habitat loss and destruction, usually as a direct result of human activity and population growth, is a major force in the loss of species, populations, and ecosystems.

Alterations in ecosystem composition, such as the loss or decline of a species, can lead to a loss of biodiversity. For example, efforts to eliminate coyotes in the canyons of southern California are linked to decreases in song bird populations in the area. As coyote populations were reduced, the populations of their prey, primarily raccoons, increased. Since raccoons eat bird eggs, fewer coyotes led to more
raccoons eating more eggs, resulting in fewer song birds.

The introduction of exotic (non-native) species can disrupt entire ecosystems and impact populations of native plants or animals. These invaders can adversely affect native species by eating them, infecting them, competing with them, or mating with them.

The over-exploitation (over-hunting, over-fishing, or over-collecting) of a species or population can lead to its demise.

Human-generated pollution and contamination can affect all levels of biodiversity.

Global climate change can alter environmental conditions. Species and populations may be lost if they are unable to adapt to new conditions or relocate.

Why is Biodiversity Important?

The diversity of life enriches the quality of our lives in ways that are not easy to quantify. Biodiversity is intrinsically valuable and is important for our emotional, psychological, and spiritual well-being. Some consider that it is an important human responsibility to be stewards for the rest of the world’s living organisms.

Diversity breeds diversity. Having a diverse array of living organisms allows other organisms to take advantage of the resources provided. For example, trees provide habitat and nutrients for birds, insects, other plants and animals, fungi, and microbes.

Humans have always depended on the Earth’s biodiversity for food, shelter, and health. Biological resources that provide goods for human use include:

  • food – species that are hunted, fished, and gathered, as well as those cultivated for agriculture, forestry, and aquaculture;
  • shelter and warmth – timber and other forest products and fibers such as wool and cotton;
  • medicines – both traditional medicines and those synthesized from biological resources and processes.

Biodiversity also supplies indirect services to humans which are often taken for granted. These include drinkable water, clean air, and fertile soils. The loss of populations, species, or groups of species from an ecosystem can upset its normal function and disrupt these ecological services. Recent declines in honeybee populations may result in a loss of pollination services for fruit crops and flowers.

Biodiversity provides medical models for research into solving human health problems. For example, researchers are looking at how seals, whales, and penguins use oxygen during deep-water dives for clues to treat people who suffer strokes, shock, and lung disease.

The Earth’s biodiversity contributes to the productivity of natural and agricultural systems. Insects, bats, birds, and other animals serve as pollinators. Parasites and predators can act as natural pest controls. Various organisms are responsible for recycling organic materials and maintaining the productivity of soil.

Genetic diversity is also important in terms of evolution. The loss of individuals, populations, and species decreases the variety of genes—the material needed for species and populations to adapt to changing conditions or for new species to evolve.

From the Ecological Society of America

Kids' Corner

More about biodiversity from the American Museum of Natural History