Biodiversity is the variety that exists among organisms and their environments. The term, short for biological diversity, is used mainly by scientists, conservationists, and others interested in the study, protection, and sustainable use of living things. Protecting biodiversity is one of the greatest challenges facing humankind. The scientists who specialize in ways to preserve it are called conservation biologists.
Kinds of biodiversity.
Scientists usually distinguish three levels of biological diversity: (1) genetic diversity, (2) species diversity, and (3) ecosystem diversity.
Genetic diversity,
the most basic level, refers to the variety of genes present in the members of a species.
Species diversity,
the most familiar type of biodiversity, refers to the variety of species in a specific place or among a specific group of organisms. Most tropical environments have greater species diversity than cooler areas do. For example, the small tropical nation of Costa Rica has at least 830 species of birds, more than Canada and the mainland United States combined.
Ecosystem diversity
refers to the variety of physical settings on earth, such as deserts, lakes, and coral reefs, and their populations of plants and animals. An ecosystem consists of the living things in a particular place and the nonliving things that are important to them. Every kind of ecosystem has a unique mix of species that differs from every other kind of ecosystem. The mix of plants and animals may differ even in rain forests on opposite sides of a mountain. If an ecosystem disappears, so do the species that live only in that ecosystem.
Protecting biodiversity.
The earth has had several periods called mass extinctions when vast numbers of species died out. Our planet has now entered another era of mass extinction. In past extinctions, species became extinct from natural causes, such as volcanic eruptions or climate change. Today, human activities are mainly responsible for the loss of biodiversity. People have hunted species to extinction and destroyed habitats by logging and plowing. They have also introduced chemical pollutants and nonnative species that harmed native plants and animals. Conservation efforts, including laws to protect endangered species and programs to create national forests, have slowed but not stopped the loss of biodiversity.
There are many reasons why it is important to maintain biodiversity. Genetic diversity provides insurance against environmental changes. At any particular place or time, the genes in certain organisms make those individuals better adapted to their environment than other members of their species. A species with a rich variety of genetic traits is better equipped to cope with change because some of its individuals will have traits that enable them to adapt to new conditions.
Species diversity is important to save potentially useful organisms. Otherwise, sources of new drugs or food crops might be wiped out before they are discovered. Ecosystem diversity helps keep the earth livable. For example, forests absorb carbon dioxide from the atmosphere. If trees are destroyed, carbon dioxide builds up and contributes to a phenomenon called the greenhouse effect. The greenhouse effect contributes to global warming, which threatens many kinds of life. Some people also think biodiversity should be maintained for its beauty. They argue that each kind of species and ecosystem is unique and adds to the richness of our world.
See Conservation with its list of Related Articles. See also Agriculture (Agriculture and the environment) ; Endangered species ; Invasive species ; Wildlife conservation .
