THE IMPORTANCE OF BIODIVERSITY

At the ecosystem level, biodiversity provides the conditions and drives the processes that sustain the global economy – and our very survival as a species. The benefits and services provided by ecosystems include:

>> Generation of soils and maintenance of soil quality
The activities of microbial and animal species – including bacteria, algae, fungi, mites, millipedes and worms – condition soils, break down organic matter, and release essential nutrients to plants. These processes play a key role in the cycling of such crucial elements as nitrogen, carbon and phosphorous between the living and non-living parts of the biosphere.

>> Maintenance of air quality
Plant species purify the air and regulate the composition of the atmosphere, recycling vital oxygen and filtering harmful particles resulting from industrial activities.

>> Maintenance of water quality
Wetland ecosystems (swamps, marshes, etc.) absorb and recycle essential nutrients, treat sewage, and cleanse wastes. In estuaries, molluscs remove nutrients from the water, helping to prevent nutrient over-enrichment and its attendant problems, such as eutrophication arising from fertilizer run-off. Trees and forest soils purify water as it flows through forest ecosystems. In preventing soils from being washed away, forests also prevent the harmful siltation of rivers and reservoirs that may arise from erosion and landslides.

>> Pest control
Around 99 per cent of potential crop pests are controlled by a variety of other organisms, including insects, birds and fungi. These natural pesticides are in many ways superior to their artificial equivalents, since pests can often develop resistance to chemical controls.

>> Detoxification and decomposition of wastes
Some 130 billion metric tons of organic waste is processed every year by earth’s decomposing organisms. Many industrial wastes, including detergents, oils, acids and paper, are also detoxified and decomposed by the activities of living things. In soils, the end product of these processes – a range of simple inorganic chemicals – is returned to plants as nutrients. Higher (vascular) plants can themselves serve to remove harmful substances from groundwater.

>> Pollination and crop production
Many flowering plants rely on the activities of various animal species – bees, butterflies, bats, birds, etc. – to help them reproduce through the transportation of pollen. More than one-third of humanity’s food crops depend on this process of natural pollination. Many animal species have evolved to perform an additional function in plant reproduction through the dispersal of seeds.

>> Climate stabilization
Plant tissues and other organic materials within land and ocean ecosystems act as repositories of carbon, helping to slow the build-up of atmospheric carbon dioxide, and thus contributing to climate stabilization. Ecosystems also exert direct influences on regional and local weather patterns. Moisture released into the atmosphere by rainforests, for example, causes regular rainstorms, limiting water loss from the region and helping to control the surface temperature. In cold climates, meanwhile, forests act as insulators and as windbreaks, helping to mitigate the impacts of freezing temperatures.

>> Prevention and mitigation of natural disasters
Forests and grasslands protect landscapes against erosion, nutrient loss, and landslides through the binding action of roots. Ecosystems bordering regularly flooding rivers (floodplain forests and wetlands) help to absorb excess water and thus reduce the damage caused by floods. Certain coastal ecosystems (salt marshes, mangrove forests, etc.) prevent the erosion of coastlines.

>> Provision of food security
Biodiversity provides the vast majority of our foodstuffs. The annual world fish catch, for example (averaging 100 million metric tons), represents humanity’s most important source of wild animal protein, with over 20 per cent of the population in Africa and Asia dependent on fish as their primary source of protein. Terrestrial animals, meanwhile, supply an array of food products: eggs, milk, meat, etc. Wild biodiversity provides a wide variety of important foodstuffs, including fruits, game meats, nuts, mushrooms, honey, spices and flavorings. These wild foods are especially important when agricultural supplies fail. Indeed, wild biodiversity guards against the failure of even the most advanced agricultural systems. For example, the productivity of many of the developed world’s agricultural crops is maintained through the regular assimilation of new genes from wild relatives of these crops. These wild genes offer resistance to the pests and diseases that pose an ever-evolving threat to harvests.

>> Provision of health care
The World Health Organization estimates that 80 per cent of people in the developing world rely on traditional medicines derived mainly from plants. In Southeast Asia, for example, traditional healers use some 6,500 different plant species to treat malaria, stomach ulcers, syphilis, and other diseases. Biodiversity is also critical to the 'formal' health sector of the developed world. A recent survey showed that of the top 150 prescription drugs used in the United States, 118 are based on natural sources. Of these, 74 per cent are derived from plants. Microbes and animal species have also contributed a range of medicines, including Penicillin (derived from the fungus Pencillium notatum) and several drugs – including anesthetics– derived from the skin secretions of tree-frog species. The medicinal importance of biodiversity is particularly impressive considering that only a tiny fraction of earth’s species have been thoroughly investigated for medicinal properties. The investigative process is continually turning up new pharmaceuticals of great promise. A recent study of cone snails, for example, has identified a painkiller that is up to a thousand times more effective than morphine, but without morphine’s addictive properties.

>> Income generation
Needless to say, the above services are all essential to the functioning of the global economy. Yet biodiversity also has great importance as a direct source of incomes and economic development. One example is 'bioprospecting' (the search for previously unknown biotic products of specific utility, such as natural pesticides, anti-fungal toxins and ‘oil-eating’ enzymes). Such discoveries join an impressive list of ‘miscellaneous’ goods provided by biodiversity, including many of our most important building materials, fibres, fuels, waxes, resins, aromatics, dyes and gums. Even in its wholly untapped state, biodiversity does great service to economies through ‘ecotourism’. People taking nature-related holidays contribute at least $500 billion per year to the national incomes of the countries they visit. Florida’s coral reefs, for example, earn around $1.6 billion per year through tourism alone.

>> Spiritual / cultural value
It’s no mystery why people are prepared to spend so much to get close to nature. Human beings instinctively derive aesthetic and spiritual satisfaction from biodiversity. Recent studies have begun to confirm what has always been known: our emotional wellbeing is enhanced by the proximity of natural beauty. The umbilical bond between humanity and biodiversity is reflected in the art, religions and traditions of diverse human cultures: a spiritual heritage that will be lost for all time if its basis – nature itself – continues to be destroyed.

Why Whales Developed Sonar

When whales first took the plunge into the ocean from land about 45 million years ago, they lacked the ability to echolocate—that is, to find and identify objects by emitting and bouncing sounds off them, much as bats do.

About 7 million years later, toothed whales (sperm whales are a type of toothed whale) developed this ability, fossils show.

Some marine biologists think that sonar in toothed whales came about as a better way to find food in the darkness of the deep ocean. But how did the whales, which primarily ate fish, know there was a large supply of food down in the dark?

Researchers at the University of California, Berkeley, suggest that giant squid would bump into the whales as the squid migrated from the dark depths to the surface at night, something they've been doing for about 200 million years.

“When whales developed sonar," explained researcher Nick Pyenson of the University of California, Berkeley, "it allowed them to dive deeper and follow the squids into the very dark ocean depths, where they discovered a rich food source that was accessible 24 hours day.”

Cephalopods, such as squid, are the most abundant and high-energy resource in the ocean and are eaten by 90 percent of all toothed whales.

The researchers detailed their idea in the European journal Lethaia.

The development of echolocation in whales and bats are strong examples of how two very different species evolved similar adaptations to their environment and passed it down to succeeding generations, a process known as convergent evolution, Pyenson noted.

“With convergent evolution, we see the same solution for being able to chase after your prey in the dark," Pyenson said, "whether you’re a bat or a whale.”

Sea Turtles' Mystery Hideout Revealed

Once sea-turtle hatchlings hit the surf, they vanish for up to five years. Where the half-dollar-size tots spend these "lost years" while ballooning to the size of dinner plates has been a mystery, until now.

New research, published today in the online edition of the journal Biology Letters, indicates the green sea turtles (Chelonia mydas) hide out in the open ocean, where they feast on jellyfish and other marine creatures.

Not only did the researchers spot their short-lived sea homes, but they discovered that these reptiles, thought to be lifelong vegetarians, are actually meat eaters as juveniles.

The results help to solve a 50-year-old mystery about the hideouts. “This has been a really intriguing and embarrassing problem for sea-turtle biologists, because so many green-turtle hatchlings enter the ocean, and we haven’t known where they go,” said study team member Karen Bjorndal, a zoologist and director of the University of Florida's Archie Carr Center for Sea Turtle Research.

Before this study, scientists had two "snapshots" that provided scant clues about the missing information on the lives of green turtles: When they hatch, the 2-inch-long (5-centimeters) sea turtles push through seemingly colossal surf. Then, between three and five years later, the now juveniles reappear closer to shore.

"Literally, when green turtles run off their nesting beach and into the ocean as little hatchlings, they disappear. And nobody sees them again [for years]," Bjorndal told LiveScience.

The scientists collected samples from the shells of 44 green sea turtles at a site near Great Inagua in the Bahamas. They analyzed heavy and light stable isotopes of carbon and nitrogen from both the oldest (earliest-grown) and newest sections of the shells. The isotopes act as fingerprints for an animal's diet (carnivore or herbivore) and where in the ocean the animal lived.

The results indicated the green sea turtles spent their lost years in the deep ocean, feeding as carnivores, before moving closer to shore and switching to a vegetarian diet of sea grasses.

The findings have implications for conservation of the green turtles, because as Bjorndal explained, "you can't protect a species if you don’t know where it is."

The magnitude of biodiversity

Biodiversity is most frequently quantified as the number of species. Estimates of the number of species currently living on Earth range widely, largely because most living species are microorganisms and tiny invertebrates, but most estimates fall between 5 million and 30 million species. Roughly 1.75 million species have been formally described and given official names. Insects comprise over half of the described species, and ~3/4 of known animal species. The number of undescribed species is undoubtedly much higher, however. Particularly in inaccessible environments, and for inconspicuous groups of organisms, collecting expeditions routinely discover many undescribed species. Estimates of the total numbers of species on Earth have been derived variously by extrapolating from the ratios of described to previously unknown species in quantitative samples, from the judgment of experts in particular taxonomic groups, and from patterns in the description of new species through time. For most groups of organisms other than vertebrates, such estimates are little more than educated guesses, explaining the wide range in estimates of global species diversity. Since insects are essentially absent from the sea, the species diversity of the oceans is generally considerably lower than terrestrial ones.

Species can be grouped on the basis of shared characteristics into hierarchical groups, or taxa, reflecting their shared evolutionary history. At the highest level of classification (or deepest branches in the evolutionary tree of life) organisms are divided into three Domains: 1) the Bacteria, which are microorganisms lacking a cellular nucleus or other membrane-bound organelles; 2) the relatively recently discovered Archaea, microorganisms of primarily extreme environments such as hot springs, which are superficially similar to Bacteria but fundamentally different at biochemical and genetic levels; and 3) the Eukarya, which include all other organisms based on nucleated cells. The Eukarya includes the four "kingdoms", the protists, animals, plants, and fungi. Each of the eukaryotic kingdoms in turn is divided into a number of phyla. At this higher taxonomic level, the oceans are far more diverse than those on land, likely reflecting the marine origins of life on Earth. Nearly half the phyla of animals occur only in the sea (e.g., the sea stars and other echinoderms), whereas only one (the obscure Onychophora, or velvet worms) is restricted to land.