Biodiversity is short for "biological diversity." The word that has come into fashion in past couple decades to describe the variety of species found in a particular habitat, region or, sometimes, the entire planet. It is often used in the context of life in the rainforest because they are so many different species found there.

Biodiversity can be measured in terms of genetic diversity (variation of genes with in species), species diversity (number of species in a given area), community diversity (variation between groups from several different species), and ecosystem diversity (variety of communities of organisms).

Biodiversity is always changing. During the last Ice Age the plant and animal diversity in Central America was relatively modest. As the climate warmed, the variety increased dramatically and then dropped when people began practicing slash and burn about 7,000 years.

Biodiversity is something people feel should be saved for environmental reasons and the benefits it can offer humans in form of new medicines and foods and protection from disease. One study found that preserving biodiversity could help protect people from diseases like AIDS, Ebola and bird flu by acting as a buffer between humans and agents the cause of the disease and providing these agents with means of dispersal other than to human beings.

Thus far about 1.5 million species of plants, animals and microorganisms have been counted. The total number of species is unknown. Estimates range from between 3 million and 100 million. Known species: around 4,600 mammals, 5,700 amphibians, 7,200 reptiles, 9,800 birds, 12,000 earthworms, 30,800 protozoa, 123,000 non-insect arthropods (spiders, etc), 751,000 insects, 26,900 algae, 69,000 fungi, 248,000 plants.

Websites and Resources: Rainforest Action Network ; Rainforest Foundation ; World Rainforest Movement ; Wikipedia article Wikipedia ; Forest Peoples Programme ; Rainforest Alliance ; Rainforest Portal ; Prince’s Rainforest Project ; Nature Conservancy ; National Geographic ; Rainforest Books: The Private Life of Plants: A Natural History of Plant Behavior by David Attenborough (Princeton University Press, 1997); Portraits of the Rainforest By Adrian Forsythe.

Websites and Resources on Rainforest Plants and Animals: Rainforest Animals ; Rainforest Animal Photos ; Rainforest Plant Photos ; Rainforest Animal Photos ; Rainforest Plants ; Enchanted Learning ; Amazon Plants ; Plants ; Biology of Plants ; ; Life Cycle of Plants / ; Scientific American articles on plants ; Dave’s Garden ; Wikipedia article Wikipedia ; Picture Gallery in German Also see the Census of Marine Life at and the Encyclopedia of Life:

Websites and Resources on Animals: ARKive Animal Info ; Animal Picture Archives (do a Search for the Animal Species You Want) animalpicturesarchive ; BBC Animals Finder ; Animal Diversity Web ; International Field Guides ; ; Encyclopedia of Life ; World Wildlife Fund (WWF) ; National Geographic National Geographic ; Animal Planet ; Wikipedia article on Animals Wikipedia ; ; Endangered Animals ; Endangered Species Resource List ; Biodiversity Heritage Library Books: Illustrated Animal Encyclopedia (Macmillian); Animal Life (DK, American Museum of Natural History) edited by zoologist Charlotte Uhlenbroek. The Encyclopedia of Life is a project to create an online reference source for very one of the 1.8 million species that are named and known on the planet and add new ones as they are discovered. The WWF is the world’s largest independent conservation body.

See Studying the Rainforest and Biodiversity and Deforestation Under Deforestation

Biodiversity in Tropical Rainforests

Tropical forests represent some 5 percent of the earth’s surface but harbor 50 percent of all living species. The biodiversity is often not apparent at first glance: many of the trees and plants in the rainforest look the same and wild life doesn't make itself apparent.

There are 29,375 plant species in Indonesia, which as vast but shrinking rainforests, compared to 3,270 in Canada. In a single tree in Amazonia, scientists found more species of ant than in the entire British Isles. At some places in the upper Amazon basin you can find 1,200 kinds of butterflies, or about 7 percent of the world's species.▸

In just one 25 acre site in Malaysia a scientist found 750 species of tree. In Peru 283 species were found in a 2.5 acre plot. By contrast there are only 700 species of tree found in all of Canada and the United States. In tropical regions, there are over 50,000 tree species in tropical areas but only around 2,000 in temperate regions. ▸

Why is there so much biodiversity in the tropical rainforest? One reason is there is not as much biodiversity in temperate zones is that they experience wide seasonal swings in temperature each year, while the tropics remain at a constant temperature. "Plants and animals in colder parts of the world," wrote Wilson, "survive in a variable environment, and as a result they range widely...A tropical species in contrast, is more likely to have evolved to fit a narrow niche in a constant environment...So when you add up all the tropical species, there are many more of them."▸

Geography is an important part of this equation. In Ecuador, for example, rainforests with rich soils are different than those with poor soils and the kinds of plants and animals vary greatly according to elevation, climate, rainfall and seasonal variations. Some ridges have an abundance of palm trees while other ridges have virtually none. One valley might be abundant with lianas, but lack a particular species of liana found everywhere else.

See Rainforest Animals.

How Many Species Are There?

Scientists still aren’t sure how many species there are. Some think around 100 million. Most think there are between 6 million and 12 million species on the whole planet. Most are insects and nematodes. Most are found in rainforests. So far scientists have described about 1.75 million species.

The biodiversity issues was brought to the forefront by Smithsonian beetle specialist Terry Erwin, who collected beetles in the late 1970s by fogging the rainforest canopy and discovering that many of the insects he trapped were new to science. In addition to the 370,000 known species of beetle he speculated that there were millions that hadn't yet been discovered.

Erwin has estimated that there are 30 million species of arthropods (insects, spiders, centipedes, etc.) living in the tropical rainforest. He arrived at this figure by first identifying 1,200 species of beetle in one species of tree in Panama. Of these beetle species, 163 were believed to be limited to that tree species. Since there are 50,000 different tree species in the rainforest he multiplied that figure by 163 and came up with 8.15 million as the total number of beetles living in the canopy. Beetles make up 40 percent all arthropod species in the canopy which, if his reasoning is sound, means that there are 20 million living insects there. There are twice as many arthropod species living in the canopy as on the ground which boosts the total figure to 30 million.▸

Other scientists have estimated that a more accurate biodiversity figure is somewhere between five and ten million arthropod species. The disagree with Erwin's contention that so many beetle species are indeed specific to one kind of tree. They argue that the beetles Erwin identified are probably found in several tree species, and thus lower the 30 million figure to five million). Erwin and other scientist now think that the 30 million species number is too low. Based on the fact that insects collected in Peru, Ecuador and Brazil are so different from one another, they now say there may be as many as 100 million species.

An accurate assessment of the true number of species in the world is still a long way from being determined. Complicating the matter are things like plant variation living on a species of trees or insect species found on a specific animal. Are certain kinds of epiphytes, for example, tree specific or can they live among a variety of tree species? There may also be entire groups of a species-specific mites that live on beetles.▸

Transitional fossils are ones that show evolution from one group to another. Once called missing links they have ancestral features of the older species as well as novel traits of the descendant. Tiktaalik Rosae is regarded as a transition fossil between sea creatures and land animals. Dated to 375 million years ago, discovered on Canada’s Ellsmere Island, it has fins like an ancestral fish but its pectoral fin contains arm bones like those of land-dwelling animals. With a bendable shoulder and elbow, plus a proto-wrist, the fin could support the body and propel it on land. Its ribs and limb bones resemble those of later four-legged amphibians and other terrestrial species.

The announcement of the discovery of Tiktaalik Rosae was made in an April 2006 article published in Nature by team of researchers lead by Neil Shubin of the University of Chicago. The scaly creature was 1.2 to 2.7 meter long and is seen as a link between scaley, armored fish like Eusthenopteron, which lived 385 million years, and Icthyostega, a land creature that lived 385 million years ago and that looked like ked a cross between a Komodo dragon and a frog.

8.7 Million Species Exist on Earth, Study Estimates

Juliet Eilperin wrote in the Washington Post, “For centuries scientists have pondered a central question: How many species exist on Earth? Now, a group of researchers has offered an answer: 8.7 million. Although the number is still an estimate, it represents the most rigorous mathematical analysis yet of what we know --- and don’t know --- about life on land and in the sea. The authors of the paper, published by the scientific journal PLoS Biology, suggest that 86 percent of all terrestrial species and 91 percent of all marine species have yet to be discovered, described and catalogued. [Source: Juliet Eilperin, Washington Post August 23, 2011]

A research team headed by marine biologist Boris Worm of Canada’s Dalhousie University, predicted there are about 7.77 million species of animals, 298,000 of plants, 611,000 of fungi, 36,400 of protozoa and 27,500 of chromists (which include various algae and water molds). Only a fraction of these species have been identified, including just 7 percent of fungi and 12 percent of animals, compared with 72 percent of plants.

“The numbers are astounding,” Jesse Ausubel, who is vice president of the Alfred P. Sloan Foundation and co-founder of the Census of Marine Life and the Encyclopedia of Life, told the Washington Post. “There are 2.2 million ways of making a living in the ocean. There are half a million ways to be a mushroom. That’s amazing to me.” Angelika Brandt, a professor at the University of Hamburg’s Zoological Museum who discovered multiple species in Antarctica, called the paper “very significant,” adding that “they really try to find the gaps” in current scientific knowledge.

Brandt, who has uncovered crustaceans and other creatures buried in the sea floor during three expeditions to Antarctica, said the study’s estimate that 91 percent of marine species are still elusive matched her own experience of discovery. “That is exactly what we found in the Southern Ocean deep sea,” Brandt said. “The Southern Ocean deep sea is almost untouched, biologically.” Researchers are still pushing to launch a series of ambitious expeditions to catalogue marine life over the next decade, including a group of Chilean scientists who hope to investigate the eastern Pacific and a separate group of Indonesian researchers who would probe their region’s waters.

If the 8.8 million estimate is correct, “those are brutal numbers,” Encyclopedia of Life executive director Erick Mata told AP. “We could spend the next 400 or 500 years trying to document the species that actually inhabit our planet.”

So far, only 1.9 million species have been found. Recent discoveries have been small and weird: a psychedelic frogfish, a lizard the size of a dime and even a blind hairy mini-lobster at the bottom of the ocean. Of the 1.9 million species found thus far, only about 1.2 million have been listed in the fledgling online Encyclopedia of Life, a massive international effort to chronicle every species that involves biologists, including Wilson. [Source: Seth Borenstein, AP, August 24, 2011]

Coming up with the Number 8.7 Million Species

Juliet Eilperin wrote in the Washington Post, “For more than 250 years, scientists have classified species according to a system established by Swedish scientist Carl Linnaeus, which orders forms of life in a pyramid of groupings that move from very broad --- the animal kingdom, for example --- to specific species, such as the monarch butterfly. Until now, estimates of the world’s species ranged from 3 million to 100 million. Five academics from Dalhousie University refined the number by compiling taxonomic data for roughly 1.2 million known species and identifying numerical patterns. They saw that within the best-known groups, such as mammals, there was a predictable ratio of species to broader categories. They applied these numerical patterns to all five major kingdoms of life, which exclude microorganisms and virus types. [Source: Juliet Eilperin, Washington Post August 23, 2011]

Worm and his team used complex mathematical models and the pace of discoveries of not only species, but of higher classifications such as family to come up with their estimate. While some new species like the strange mini-lobster are in exotic places such as undersea vents, “many of these species that remain to be discovered can be found literally in our own backyards,” Mora said. [Source: Seth Borenstein, AP, August 24, 2011]

One of the reasons so many species have yet to be catalogued is that describing and cataloguing them in the scientific literature is a painstaking process, and the number of professional taxonomists is dwindling. Smithsonian Institution curator Terry Erwin, a research entomologist, said fewer financial resources and a shift toward genetic analysis has cut the number of professional taxonomists at work. Erwin noted that when he started at the Smithsonian in 1970 there were 12 research entomologists, and now there are six. “Unfortunately, taxonomy is not what cutting-edge scientists feel is important,” Erwin said. [Source: Eilperin, Washington Post]

Erwin said researchers would continue to search for the best way to quantify global diversity beyond the new method. Erwin himself has been using a biodegradable insecticide since 1972 to fog trees in the Amazon and kill massive amounts of insects, which he and his colleagues have classified. Based on such sampling, Erwin posited in 1982 that there were roughly 30 million species of terrestrial arthropods --- insects and their relatives --- worldwide.

Extrapolating from that sample to determine a global total, he said, was a “mistake, one which others have repeated,” he said. Erwin added he still thinks counting actual specimens is the best route, noting he and his students determined in 2005 that there are more than 100,000 species of insects in a single hectare (or 2.5 acres) of the Amazon. Noting that insects and their relatives count for 85 percent of life on Earth, he wondered why there’s such a fuss about counting the rest of the planet’s inhabitants: “Nothing else counts.”

Outside scientists, such as Wilson and preeminent conservation biologist Stuart Pimm of Duke University, praised the study, although some said even the 8.7 million number may be too low. The study said it could be off by about 1.3 million species, with the number somewhere between 7.5 million and 10.1 million. But evolutionary biologist Blair Hedges of Penn State University said he thinks the study is not good enough to be even that exact and could be wrong by millions.

Hedges knows firsthand about small species. He found the world’s smallest lizard, a half-inch long Caribbean gecko, while crawling on his hands and knees among dead leaves in the Dominican Republic in 2001. And three years ago in Barbados, he found the world’s shortest snake, the 4-inch Caribbean threadsnake that lays “a single, very long egg.”

Significance of Having so Many Species

While some scientists and others may question why we need to know the number of species, others say it’s important. There are potential benefits from these undiscovered species, which need to be found before they disappear from the planet, said famed Harvard biologist Edward O. Wilson, who was not part of this study. Some of modern medicine comes from unusual plants and animals. “We won’t know the benefits to humanity (from these species), which potentially are enormous,” the Pulitzer Prize-winning Wilson said. “If we’re going to advance medical science, we need to know what’s in the environment.” "Many species may vanish before we even know of their existence, of their unique niche and function in ecosystems, and of their potential contribution to improved human well-being," said UH researcher Camilo Mora, a lead author of the study. [Source: Seth Borenstein, AP, August 24, 2011]

The new analysis of species numbers is significant, Juliet Eilperin wrote in the Washington Post, “not only because it gives more detail on a fundamental scientific mystery but because it helps capture the complexity of a natural system that is in danger of losing species at an unprecedented rate. Worm compared the planet to a machine with 8.7 million parts, all of which perform a valuable function. “If you think of the planet as a life-support system for our species, you want to look at how complex that life-support system is,” Worm said. “We’re tinkering with that machine because we’re throwing out parts all the time.”

He noted that the International Union for Conservation of Nature produces the most sophisticated assessment of species on Earth, a third of which it estimates are in danger of extinction, but its survey monitors less than 1 percent of the world’s species. In a companion essay to the 8.7 species article in PLoS Biology, Oxford University zoologist Robert M. May wrote that identifying species is more than a “stamp collecting” pastime, to which a Victorian physicist once compared it. He noted that crossing conventional rice with a new variety of wild rice in the 1970s made rice farming 30 percent more efficient.

“We are really fairly ignorant of the complexity and colorfulness of this amazing planet,” Worm said. “We need to expose more people to those wonders. It really makes you feel differently about this place we inhabit.”

Two Hundred New Species Found in Papua New Guinea Mountains

Reuters reported in October 2010, “Some 200 new species of animals and plants, including an orange spider, a jabbing spiny-legged katydid (bush cricket) and a minute long-nosed frog, have been discovered in Papua New Guinea's remote jungle-clad mountains. A team of international scientists made the discoveries during a two-month expedition in the remote Nakanai and Muller mountains in 2009, Conservation International said. [Source: Reuters, October 7, 2010]

The expedition was part of a global project to document the biodiversity of poorly known but species-rich environments and raise conservation priorities. In the Nakanai mountains on New Britain island, the team found 24 new species of frogs, two new mammals and nine new species of plants. They also found nearly 100 new insects including damselflies, katydids and ants, and approximately 100 new spiders. Several of the katydids and at least one ant and one mammal are so different from any known species that they represent entirely new genera, said the scientists.

During of the survey of the Muller mountains in the Southern Highlands, the scientists camped as high as 2,875 metres (8,625 feet), discovering a katydid which, when threatened, holds its large and spiny legs above its head to jab at predators."We hope that news of these amazing new species will bolster the nomination of these spectacular environments for World Heritage status," team leader Stephen Richards said, announcing the discoveries.

For thousands of years, PNG's steep mountain ranges and dense forests have restricted interaction between indigenous groups, creating one of the world's most culturally and linguistically diverse countries. The same geographic barriers have also limited scientific exploration. "As we flew in to land the helicopter in a mountain meadow, zooming into this spectacular landscape, it was an incredible realisation, knowing that no scientist has ever been there before," said Richards.

Papua New Guinea's rugged terrain may be conservation's most powerful ally, said the scientists, but warned some of the country's forests were facing increasing threats from subsistence agriculture, logging and oil palm production. "Standing on top of the Nakanai mountains, I could see oil palm plantations extending almost to the coast," said Richards. "It struck me just how much of the lowland forest has disappeared for oil palm. The steepness of the highlands has limited their destruction, but if people start building roads, these areas will be more accessible."Reuters

Scientists Find 200 New Frog Species in Madagascar

In May 2009, Richard Lough of Reuters wrote: “Scientists have found more than 200 new species of frogs in Madagascar but a political crisis is hurting conservation of the Indian Ocean island's unique wildlife, a study shows. The discovery, which almost doubles the number of known amphibians in Madagascar, illustrates an underestimation of the natural riches that have helped spawn a $390-million-a-year tourism industry. [Source: Richard Lough, Reuters, May 6, 2009]

However, months of instability culminating in a change of government after street protests, have compromised gains in conservation. "The political instability is allowing the cutting of the forest within national parks, generating a lot of uncertainty about the future of the planned network of protected areas," David Vieites, researcher at the Spanish National Natural Sciences Museum, said in a statement.

The world's fourth-largest island, known for exotic creatures such as the ring-tailed lemur and poisonous frogs, is a biodiversity hotspot. More than 80 percent of the mammals in Madagascar are found nowhere else, while all but one of the 217 previously known species of amphibian are believed by scientists to be native."People think that we know which plant and animal species live on this planet," team member Miguel Vences, professor at the Technical University of Braunschweig, said in the statement. "But the centuries of discoveries has only just begun -- the majority of life forms on Earth is still awaiting scientific recognition."

Human demands on the land and decades of rampant logging have destroyed 80 percent of Madagascar's rain forest, threatening hundreds of species, he said.The study, carried out by the Spanish Scientific Research Council (CSIC), and published in the May issue of the journal Proceedings of the National Academy of Sciences, suggests the find of between 129 and 221 new species of frogs could double the number of amphibians globally if the results are extrapolated worldwide. Almost a quarter of the new species discovered have not yet been found in unprotected areas, the study stated.

Biodiversity Vital to Keeping Streams Clean

Deborah Zabarenko of Reuters wrote: “As Earth enters a period of mass extinction, a study offers a new reason to preserve biodiversity: it's an effective, natural pollution scrubber in streams. Environmental activists have long warned that waning biodiversity means the loss of such ecological services as stream-cleaning, control of pests and diseases and increased productivity in fisheries. The latest study, published in the journal Nature, shows how this works, demonstrating that streams that contain more species have better water quality than streams that have fewer. [Source: Deborah Zabarenko, Reuters, April 6, 2011]

The species being discussed are microorganisms such as algae that incorporate elements of pollution into their bodies. The more types of algae there are in a stream, each with a minutely different habitat, the better they are collectively at filtering pollution out of the water. "If we were to maintain streams in their naturally diverse state, these streams that we love for their recreation, for their beauty, for fishing, etc. ... have the tangential benefit of cleaning up our water for us," said Bradley Cardinale, the study's author. "One implication (of the study) is, if we let nature do its thing, we don't have to run around creating very expensive water treatment plants all over the planet," Cardinale, of the University of Michigan, said by telephone.

To reach his conclusions, Cardinale set up 150 miniature model streams that mimic the varied conditions of natural streams in the United States. He added from one to eight varieties of algae and measured how well the mini-streams got cleaned.The pollutant they targeted was a nitrogen compound called nitrate, a common by-product of chemical fertilizers that Cardinale called "the world's single greatest water quality problem."Nitrate is responsible for the hypoxic "dead zone" in the Gulf of Mexico, outbreaks of toxic algae and red tides, he said.

The full eight-species mix of algae removed nitrate from streams 4.5 times faster, on average, than a single species alone, according to the study, which was funded by the National Science Foundation. One species known as filamentous snotty algae does a good job on its own of taking in nitrate and other excess nutrients from stream water. But it smells bad and most other species don't like to eat it, Cardinale said.

Knowing the benefits of biodiversity is important because scientists see Earth entering a period of mass extinction when as much as 75 percent or more of the life on the planet vanishes forever. Cardinale said there is little doubt that this trend, largely due to the destruction of places where many different species live, has already begun."It's not necessarily how much we've lost already," he said. "It's that the rate of extinction is so outrageously high compared to what we know is normal."The rates of extinction now are between 100 to 1,000 times faster than normal, and between 30 percent and 50 percent of species could be lost by 2100, Cardinale said.

Water in New York is cleaned by the biodiversity of the nearby Catskill watershed. Thomas E. Lovejoy, professor of environmental science and policy at George Mason University, wrote in the Washington Post , “Back in the 1990s the quality of New York water --- once rated as some of the best of any city --- had declined so badly that the Environmental Protection Agency was about to require the city to build an $8 billion water treatment plant. Instead, for a fraction of that cost, the city restored the watershed’s ecosystems and biodiversity so that they once again could provide high quality drinking water. In doing so, one of the wealthiest cities in the world was recognizing explicitly the value of an ecosystem service.

Image Sources: Wikimedia Commons

Text Sources: Mostly National Geographic articles. Also Life on Earth by David Attenborough (Princeton University Press), New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Natural History magazine, Discover magazine, Times of London, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.

Last updated March 2011

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