What is Biodiversity?
Frequently Asked Questions
What
is biodiversity?
What
is an ecosystem? What is a species?
Why
does biodiversity consist of several parts, such as genetic
diversity, species diversity and ecosystem diversity?
Where
is most of the biodiversity of the Earth located?
What
are the threats to biodiversity?
Why
should we conserve biodiversity?
What
can I do to help conserve biodiversity?
Where
can I go for more information on biodiversity?
Biodiversity, short for "biological diversity," refers to the variety of life on Earth. There are many levels of diversity—from DNA and genes
to species, populations, ecosystems, and communities.
Genetic diversity refers to the variety of genes within individual plants and animals and between different species. Think of the seedlings that grow from a packet of new seeds—or the variety of people within your own family. No two plants—and no two people—are exactly alike.
Species diversity refers to the variety of different types of plants and animals, including bacteria, fungi, insects, mammals, plants, and everything in between. Differences occur within and between populations of species.
Ecosystem diversity refers to the variety of habitats and climates on Earth. The interactions between these ecosystems and the species that live in them underpin all life on Earth. In fact, Earth's biodiversity helps keep our air and water clean, regulates our climate, and provides us (and other plants and animals) with food, shelter, clothing, medicine, and other useful products. What makes life on Earth so complex is this diversity and how it all interacts.
Q: What is a species? What is an ecosystem?
A
species is a group or population of similar organisms that
reproduce among themselves but do not naturally reproduce
with any other kinds of organisms. Examples of species include
this splashback poison dart frog (right), monarch butterflies,
red oak trees, and humans.
According to the scientists of the Ecological Society of America, an ecosystem is any geographic area, including the living organisms that live there and the nonliving parts of the physical environment. Energy and matter move through and are stored in the living and nonliving things—and the interactions between them—within the ecosystem. Ecosystems are living places. Examples include tropical and temperate forests, deserts, mountain tops, coral reefs, wetlands, and prairies.
Q: Why does biodiversity consist of several parts—genetic diversity, species diversity, and ecosystem diversity?
Life on Earth takes a variety of forms, and all these parts are needed to keep the Earth healthy. Genetic diversity ensures that parents pass on the traits (such as disease resistance and physical features) that their offspring need to survive. When small populations are isolated from other populations of their species, they may be forced to inbreed, possibly leading to a loss of genetic diversity and to the extinction of the population.
Species diversity ensures that ecosystems survive. For example, a giraffe cannot do the same pollination job as a bee, nor could a bee play the same role in a savanna ecosystem as a giraffe. There are some species that depend on a single species to survive. Sloth moths live only on sloths. African melons depend solely on aardvarks. When a species disappears, it can affect a whole ecosystem.
Ecosystem diversity ensures the health of the entire planet. For example, rainforests act as filters for the Earth's air, absorbing carbon dioxide and releasing oxygen. Oceans also absorb carbon dioxide, a well-known greenhouse gas that causes global warming. Wetlands and estuaries act as filters for the Earth's freshwaters and nurseries for the Earth's marine populations. Without these ecosystems, life on Earth would be very different than what it is today.
Q: Where is most of the biodiversity of the Earth located?
Even though they cover less than 10 percent of the planet's land surface, tropical rainforests contain more than half of all species. The rainforests
of Central and South America, equatorial Africa and Southeast
Asia are home to millions of species of plants and animals. Coral reefs,
the "rainforests of the sea," are home to one-quarter of all marine life.
Deserts, prairies, wetlands, estuaries, ocean bottoms, mountain tops, temperate forests—even city parks, school yards, and backyards—are all home to diverse communities of plants and animals.
Q: What are the threats to biodiversity?
Many human activities, which stem from the population explosion of the past few decades and how we live, threaten biodiversity. There are 6 billion humans on Earth today, and that number may reach 9 to 12 billion in the next 50 to 100 years. In addition, humans are using proportionally more energy, land, water, and natural resources (such as trees, fossil fuels, minerals, plants, and animals) than ever before. Devastating effects of our species on the world include:
- Habitat Fragmentation
and Degradation
Some species require large areas of land or water in which to nest, forage, migrate, and mate. Human beings are encroaching on the habitats of many species. Land is constantly being converted from its natural state into farms, cattle grazing areas, mines, housing developments, golf courses, office buildings, shopping malls, and other urban and suburban areas.
For all species, smaller habitats mean fewer food and shelter resources. Scientists have discovered that decreasing the size of natural habitats—even if these habitats are protected in nature parks or preserves—increases the chances of species going extinct. Smaller, isolated habitats are like islands, completely separated from one another. As a result, species living in these habitats compete with each other and with humans for limited resources. Since their populations are so small, they have fewer mates with whom to reproduce, diminishing the genetic diversity of their populations. If other habitats are not close by, species may not be able to migrate or to disperse seeds to other habitats. In fact, migrating species like birds and butterflies face fragmented habitats along their entire migrating route.
- Global Climate Change
As humans burn more fossil fuels like oil and coal for energy, more carbon dioxide enters the atmosphere. Carbon dioxide acts like a greenhouse, letting sunlight and heat into the lower atmosphere, but not letting them back out. Other gases, including methane and nitrous oxide, released into the atmosphere due to human activities also contribute to global warming. As a result, average yearly temperatures on Earth have risen.
Climate changes will change the ecosystems in which many species—including humans—live. If a species requires a certain temperature or certain amount of water to live, it could face extinction if global climate change alters its environment. Other species—such as mosquitoes, certain diseases, and some pests—may flourish and expand their ranges.
- Pollution
Chemicals we use every day on our crops or in our homes to kill unwanted pests and weeds can also harm or even kill other plant and animals species. Pesticides are often misused, used incorrectly, or used over too large an area. But even if used correctly, many cannot tell the difference between a pest and a friendly species. For example, some pesticides used on crops can harm the bees and other insects needed to pollinate these same crops. In addition, many chemicals have long lives and do not break down easily. They can "bioaccumulate" in food webs—as birds eat bugs, and larger animals eat birds, more and more harmful chemicals accumulate in the tissues of each animal in the food chain. Not only are species harmed themselves, but the foods they eat are also harmed.
- Overfishing, Hunting, and
Poaching
Many of the world's natural resources are being used by humans faster than they can replace themselves. Commercial sea life, such as lobsters, swordfish, and salmon, are overharvested, while species like dolphins and sea turtles sometimes die in fishing nets. A $10-billion-a-year market in wildlife and wildlife products threatens African elephants and rhinos, Asiatic bears, pandas, and tigers, seahorses, corals, and tropical plants and birds with extinction. People buy wildlife and wildlife products to use as pets, medicines, gourmet foods or decorative objects. Each year, consumers in the United States alone buy as many as 12,000 primates, 2.5 million orchids, 200,000 live birds, 2 million reptiles, 250 million tropical fish, and millions of wildlife products. Nearly one-quarter of this trade—around $2.5 billion—is illegal because the species being poached are endangered. What’s more, the illegal poaching of wildlife is worsened by deforestation. Once habitats are accessible by roads, it is easier to take animals from their natural environments.
- Introducing Non-Native Species
Purposely or accidentally, humans often bring new species wherever they go. Some introduced species can be beneficial. The dung beetle, which was introduced to Australia, is now helping alleviate the problem of too much cow dung on ranches. Most introduced species—also called alien, invasive or exotic species—can harm native species and ecosystems, however. Introduced species have no natural predators or diseases in their new habitat, so their numbers expand quickly. In addition, native species have no defenses against this new source of predator attacks or of competition for food or living space.
For example, in the 1980s the Zebra mussel was accidentally introduced to the Great Lakes through the draining of ballast water from a foreign ship. The freshwater mollusk has now spread throughout most of the northeastern and midwestern United States. It clogs intake valves for pumping stations, power plants and industrial facilities, and obstructs boating and sports fishing. In addition, it has caused the declines of some native freshwater species, harming local ecosystems.
The numbers of species introduced to areas in which they are not native are expected to increase as the scale of international trade, transportation and tourism continues to grow. People, resources and species move across borders more easily than ever before. As a result, the effects of introduced species on native species could worsen.
Q: Why should we conserve biodiversity?
Life
on Earth as we know it would not exist if its rich biodiversity
were severely altered. Species (including humans) and the
ecosystems in which they live are linked together though the
flows of energy and materials.
A change in the life of one species—especially extinction—could ripple throughout an ecosystem, changing the life
of many other species, including humans.
Harming the world's biodiversity could have serious repercussions. For instance, overlogging forests fragments and destroys habitat for the animals that live in the forests. It can threaten some plant species with extinction, and can take away the trees we need to clean our air and water and to keep our soils, rivers, lakes, streams, and oceans healthy. It can also lead to flooding and mudslides. Or, what if the world had no more pollinators—animals like bees, flies, butterflies, moths, birds, and bats—that pollinate flowers so that fruit can grow? Harm the habitats in which pollinators live—or harm the pollinators themselves—and you reduce the food many animal species eat every day.
Q: What can I do to help conserve biodiversity?
There are many things you can do to help! Here are just a few:
- Learn more. Talk to scientists. Visit museums, botanical gardens, nature centers, parks, zoos, and aquariums. Read books and magazines about environmental topics. Surf the Web. Contact environmental organizations, universities, and government agencies. The more you learn about biodiversity, the more you can do to help protect it.
- Donate your time and money to environmental organizations doing biodiversity conservation work.
- Volunteer at the National Zoo! or support our work by becoming a Friend of the National Zoo.
- Buy eco-friendly products, such as paper made from recycled materials. Buy products that don't use fossil fuels or toxic chemicals. Buy locally-grown, organic foods. Buy wood products from sustainably grown, not endangered, tree species. Don't buy exotic, non-native pets or products made from endangered species.
- Drive less. Use eco-friendly transportation like subways, bikes and carpools.
- Be energy efficient. Use energy-efficient appliances and computers. Use compact fluorescent light bulbs.
- Don't use pesticides, fertilizers, and other chemicals on your lawn and garden. Plant native vegetation and flowers that bees, butterflies, hummingbirds, and other pollinators will like.
- Spread the word! Tell others what you know.
- See our Green Team Tips and ideas on how to think globally and act locally.
Q: Where can I go for more information on biodiversity?
Many people and organizations around the world working to help protect biodiversity.
Here are some websites you may find useful:
World
Wildlife Fund
Conservation
International
The
Nature Conservancy
The
Ecological Society of America
Convention
on Biological Diversity, Secretariat
Endangered Species Program, Fish and Wildlife Service
World Resources Institute
The
Virtual Library of Ecology and Biodiversity
Read
MAB's booklet on biodiversity conservation called Working
for Biodiversity. (This is a PDF file and requires
Adobe Acrobat.)
It can help answer more of your questions.
