Encyclopedic Entry
biodiversity
Biodiversity refers to all the different kinds of living organisms within a given area. Biodiversity includes plants, animals, fungi, and other living things. Biodiversity can include everything from towering redwood trees to tiny, single-cell algae that are impossible to see without a microscope.
Kinds of Biodiversity
A common way to measure biodiversity is to count the total number of species living within a particular area. Tropical regions, areas that are warm year-round, have the most biodiversity. Temperate regions, which have warm summers and cold winters, have less biodiversity. Regions with cold or dry conditions, such as mountaintops and deserts, have even less.
Generally, the closer a region is to the Equator, the greater the biodiversity. At least 40,000 different plant species live in the Amazon rain forest of South America, one of the most biologically diverse regions on the planet. Only about 2,800 live in Canada’s Quebec province.
The warm waters of the western Pacific and Indian Oceans tend to be the most diverse marine environments. The Bird’s Head Seascape in Indonesia is home to more than 1,200 species of fish and 600 species of coral. Many of the corals build coral reefs, which are home to hundreds more species, from tiny seaweeds to large sharks.
Some places in the world have a large number of endemic species—species that exist only in that place. The Cape Floristic Region in South Africa is home to about 6,200 plant species found nowhere else in the world. Areas with high numbers of endemic species are called biodiversity hotspots. Scientists and communities are For the complete encyclopedic entry with media resources, visit:
http://nationalgeographic.org/encyclopedia/biodiversity/
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making a special effort to preserve biodiversity in these regions.
Biodiversity can also refer to the variety of ecosystems—communities of living things and their environments. Ecosystems include deserts, grasslands, and rain forests. The continent of Africa is home to tropical rain forests, alpine mountains, and dry deserts. It enjoys a high level of biodiversity. Antarctica, covered almost entirely by an ice sheet, has low biodiversity.
Another way to measure biodiversity is genetic diversity. Genes are the basic units of biological information passed on when living things reproduce. Some species have as many as 400,000 genes. (Human beings have about 25,000 genes, while rice has more than 56,000.) Some of these genes are the same for all individuals within a species—they’re what make a daisy a daisy and a dog a dog. But some genes within a species are different. This genetic variation is why some dogs are poodles and some are pit bulls. It’s why some people have brown eyes and some people have blue eyes.
Greater genetic diversity in species can make plants and animals more resistant to diseases. Genetic diversity also allows species to better adapt to a changing
environment.
Importance of Biodiversity
All species are interconnected. They depend on one another. Forests provide homes for animals. Animals eat plants. The plants need healthy soil to grow. Fungi help decompose organisms to fertilize the soil. Bees and other insects carry pollen from one plant to another, which enables the plants to reproduce. With less
biodiversity, these connections weaken and sometimes break, harming all the species in the ecosystem.
Ecosystems with a lot of biodiversity are generally stronger and more resistant to disaster than those with fewer species. For instance, some diseases kill only one kind of tree. In the early 1900s, American chestnut blight killed most of the
chestnut trees in the eastern forests of North America. The forest ecosystem survived because other kinds of trees also grew there.
Biodiversity is important to people in many ways. Plants, for instance, help humans by giving off oxygen. They also provide food, shade, construction material,
medicines, and fiber for clothing and paper. The root system of plants helps prevent flooding. Plants, fungi, and animals such as worms keep soil fertile and water clean. As biodiversity decreases, these systems break down.
Hundreds of industries rely on plant biodiversity. Agriculture, construction, medical and pharmaceutical, fashion, tourism, and hospitality all depend on plants for their success. When the biodiversity of an ecosystem is interrupted or destroyed, the economic impact on the local community could be enormous.
Biodiversity is especially important to the medical and pharmaceutical industries. Scientists have discovered many chemicals in rain forest plants that are now used in helpful drugs. One of the most popular and safe pain relievers, aspirin, was originally made from the bark of willow trees. Medicines that treat some forms of cancer have been made from the rosy periwinkle, a flower that grows on the African island of Madagascar. Scientists have studied only a small percentage of rain forest species in their search for cures. But every year, thousands of species go extinct, or die out entirely, before scientists can determine whether they might be useful in medicines.
Decreasing Biodiversity
In the past hundred years, biodiversity around the world has decreased dramatically. Many species have gone extinct. Extinction is a natural process; some species naturally die out while new species evolve. But human activity has changed the natural processes of extinction and evolution. Scientists estimate that species are dying out at hundreds of times the natural rate.
A major reason for the loss of biodiversity is that natural habitats are being
destroyed. The fields, forests, and wetlands where wild plants and animals live are disappearing. Land is cleared to plant crops or build houses and factories. Forests are cut for lumber and firewood. Between 1990 and 2005, the amount of forested land in Honduras, for instance, dropped 37 percent.
As habitats shrink, fewer individuals can live there. The creatures that survive have fewer breeding partners, so genetic diversity declines.
Pollution, overfishing, and overhunting have also caused a drop in biodiversity. Global climate change—the latest rise in the average temperature around the globe, linked to human activity—is also a factor. Warmer ocean temperatures damage fragile ecosystems such as coral reefs. A single coral reef can shelter 3,000 species of fish and other sea creatures such as clams and sea stars.
Biodiversity can also be harmed by introduced species. When people introduce species from one part of the world to another, they often have no natural
predators. These non-native species thrive in their new habitat, often destroying native species in the process. Brown tree snakes, for instance, were accidentally brought into Guam, an island in the South Pacific, in the 1950s. Because brown tree snakes have no predators on Guam, they quickly multiplied. The snakes, which hunt birds, have caused the extinction of nine of the island’s 11 native forest-dwelling bird species.
People all over the world are working to maintain the planet’s biodiversity. In the United States, the Endangered Species Act protects about 2,000 organisms that are in danger of becoming extinct. Animals and plants are the most familiar types of endangered species, but a fungus, such as the white ferula mushroom can also be threatened. The white ferula mushroom, a delicacy that only grows on the Italian island of Sicily, helps decompose organic compounds such as plants. Some environmental groups are working to create a sustainable mushroom population to satisfy consumers as well as the local ecosystem.
Around the globe, thousands of wilderness areas have been set up to conserve plants, animals, and ecosystems. Local, national, and international organizations are cooperating to preserve the biodiversity of regions threatened by development or natural disasters. UNESCO’s World Heritage Site program recognizes areas of global importance, such as the enormous wetland region of the Pantanal in South America. Many national parks, such as Glacier National Park in the U.S. state of Montana, protect biodiversity within the park by restricting extractive activities, such as mining and drilling.
Marine protected areas (MPAs) have been established to preserve sea life. In the marine protected area around Australia’s Great Barrier Reef, no-fishing zones
have helped fish populations thrive. People are also working to limit pollution and restore coral reef ecosystems in the area. As ecosystems become healthier, their biodiversity increases.
Vocabulary
Term Part of
Speech Definition
adapt verb to adjust to new surroundings or a new situation.
agriculture noun the art and science of cultivating the land for growing
crops (farming) or raising livestock (ranching).
algae plural
noun
(singular: alga) diverse group of aquatic organisms, the largest of which are seaweeds.
alpine adjectivehaving to do with mountains.
animal noun
organisms that have a well-defined shape and limited growth, can move voluntarily, acquire food and digest it internally, and can respond rapidly to stimuli.
aspirin noun drug for relieving pain and reducing inflammation, or
swelling.
biodiversity noun all the different kinds of living organisms within a given
area.
breed verb to produce offspring.
brown tree
snake noun reptile native to Australia and Papua New Guinea.
cancer noun growth of abnormal cells in the body.
chemical noun molecular properties of a substance.
chestnut blightnoun disease, caused by a fungus, that can be fatal to
chestnut trees.
climate changenoun gradual changes in all the interconnected weather
elements on our planet.
conserve verb to save or use wisely.
coral noun tiny ocean animal, some of which secrete calcium
carbonate to form reefs.
coral reef noun rocky ocean features made up of millions of coralskeletons.
crop noun agricultural produce.
decrease verb to lower.
delicacy noun food or dish notable for its rarity or cost.
desert noun area of land that receives no more than 25 centimeters
(10 inches) of precipitation a year.
disease noun a harmful condition of a body part or organ.
drill verb to make a hole using a rotating digging tool.
drug noun chemical substance used to change the physical or
mental state of an organism.
dwelling noun a place to live.
economic adjectivehaving to do with money.
ecosystem noun community and interactions of living and nonliving things
in an area.
Endangered
Species Act noun
(1973) U.S. legislation that protects endangered species when they are threatened by human activity.
endemic
species noun species that naturally occurs in only one area or region.
environment noun conditions that surround and influence an organism or
community.
Equator noun imaginary line around the Earth, another planet, or star
running east-west, 0 degrees latitude.
evolve verb to develop new characteristics based on adaptation and
natural selection.
extinct adjectiveno longer existing.
extractive
activity noun
process that removes, or extracts, any natural or cultural resource from an area.
fertile adjectiveable to produce crops or sustain agriculture.
fertilize verb to make productive or fertile.
fiber noun long, thin, threadlike material produced by plants that aids
digestive motion when consumed.
fragile noun delicate or easily broken.
fungus noun
(plural: fungi) type of organism that survives by decomposing and absorbing the material in which it grows.
gene noun part of DNA that is the basic unit of heredity.
Term Part of
genetic
diversity noun
difference or variety of units of inheritance (genes) in a species.
genetic
variation noun
differences in the genes among individual members of a species.
grassland noun ecosystem with large, flat areas of grasses.
Great Barrier
Reef noun large coral reef off the northeast coast of Australia.
habitat noun environment where an organism lives throughout the
year or for shorter periods of time.
hospitality noun the treatment of guests.
ice sheet noun thick layer of glacial ice that covers a large area of land.
international
organization noun
unit made up of governments or groups in different countries, usually for a specific purpose.
introduced
species noun
a species that does not naturally occur in an area. Also called alien, exotic, or non-native species.
marine adjectivehaving to do with the ocean.
mining noun process of extracting ore from the Earth.
MPA noun (marine protected area) area of the ocean where a
government has placed limits on human activity.
overfish verb to harvest aquatic life to the point where species become
rare in the area.
overhunt verb to capture and kill enough animals to reduce their
breeding population below sustainable levels.
Pantanal noun
largest wetland area in the world, in western Brazil, Bolivia, and Paraguay (more than 150,000 square kilometers/58,000 square miles).
pharmaceuticalnoun drug or having to do with drugs and medications.
plant noun organism that produces its own food through
photosynthesis and whose cells have walls.
pole noun extreme north or south point of the Earth's axis.
pollen noun
powdery material produced by plants, each grain of which contains a male gamete capable of fertilizing a female ovule.
Term Part of
pollinate verb to transfer pollen from one part of a flower (the anther)
to another (the stigma).
pollution noun introduction of harmful materials into the environment.
predator noun animal that hunts other animals for food.
province noun division of a country larger than a town or county.
rain forest noun area of tall, mostly evergreen trees and a high amount of
rainfall.
root system noun all of a plant's roots.
rosy periwinklenoun flowering plant native to the African island of Madagascar,
used in medicines.
seaweed noun
marine algae. Seaweed can be composed of brown,
green, or red algae, as well as "blue-green algae," which is actually bacteria.
sustainable adjectiveable to be continued at the same rate for a long period of
time.
temperate adjectivemoderate.
temperature noun degree of hotness or coldness measured by a
thermometer with a numerical scale.
thrive verb to develop and be successful.
tropical adjective
existing in the tropics, the latitudes between the Tropic of Cancer in the north and the Tropic of Capricorn in the south.
UNESCO noun the United Nations Educational, Scientific, and Cultural
Organization.
wetland noun area of land covered by shallow water or saturated bywater.
white ferula
mushroom noun
fungus native to the Italian island of Sicily, used in cooking.
wilderness noun environment that has remained essentially undisturbed by
human activity.
World Heritage
Site noun
location recognized by the United Nations as important to the cultural or natural heritage of humanity.
Term Part of
Speech Definition
Articles & Profiles
Hotspots"
Audio & Video
National Geographic Video: A New Perspective on Biodiversity
Websites
National Geographic: BioBlitz
Discover Life in America: All Taxa Biodiversity Inventory Database International Year of Biodiversity
National Geographic in the Field: African Bat Biodiversity Project
