FANDOM


View from Bukit Terisek

Rainforests are among the most biodiverse ecosystems on earth

Biodiversity or biological diversity is the variation of taxonomic life forms within a given ecosystem, biome or for the entire Earth. Biodiversity is often a measure of the health of biological systems to indicate the degree to which the aggregate of historical species are viable versus extinct.

Etymology

Biodiversity is a neologism and a portmanteau word, from bio and diversity.The Science Division of The Nature Conservancy used the term "natural diversity" in a 1974 study, "The Preservation of Natural Diversity." The term biological diversity was used even before that by conservation scientists like Robert E. Jenkins and Thomas Lovejoy. The word biodiversity itself may have been coined by W.G. Rosen in 1985 while planning the National Forum on Biological Diversity organized by the National Research Council (NRC) which was to be held in 1986, and first appeared in a publication in 1988 when entomologist E. O. Wilson used it as the title of the proceedings [1] of that forum[2]. The word biodiversity was deemed more effective in terms of communication than biological diversity.

Since 1986 the terms and the concept have achieved widespread use among biologists, environmentalists, political leaders, and concerned citizens worldwide. It is generally used to equate to a concern for the natural environment and nature conservation. This use has coincided with the expansion of concern over extinction observed in the last decades of the 20th century.

The term "natural heritage" predates "biodiversity," and means pretty much the same thing, though it is less of a scientific term and more easily comprehended in some ways by the wider audience interested in conservation. "Natural Heritage" was used when Jimmy Carter set up the Georgia Heritage Trust while he was governor of Georgia; Carter's trust dealt with both natural and cultural heritage. "Natural Heritage" was then picked up by the Science Division of The Nature Conservancy when, under Jenkins, it launched in 1974 the network of State Natural Heritage Programs. When this network was extended outside the US, the term "Conservation Data Center" was suggested by Guillermo Mann and came to be preferred.

Definitions

The most straightforward definition is "variation of life at all levels of biological organization"[3]. A second definition holds that biodiversity is a measure of the relative diversity among organisms present in different ecosystems. "Diversity" in this definition includes diversity within a species and among species, and comparative diversity among ecosystems.

A third definition that is often used by ecologists is the "totality of genes, species, and ecosystems of a region". An advantage of this definition is that it seems to describe most circumstances and present a unified view of the traditional three levels at which biodiversity has been identified:

This third definition, which conforms to the traditional five organization layers in biology, provides additional justification for multilevel approaches.

The 1992 United Nations Earth Summit in Rio de Janeiro defined "biodiversity" as "the variability among living organisms from all sources, including, 'inter alia', terrestrial, marine, and other aquatic ecosystems, and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems". This is, in fact, the closest thing to a single legally accepted definition of biodiversity, since it is the definition adopted by the United Nations Convention on Biological Diversity. The parties to this convention include all the countries on Earth, with the exception of Andorra, Brunei Darussalam, the Holy See, Iraq, Somalia, and the United States of America.

If the gene is the fundamental unit of natural selection, according to E. O. Wilson, the real biodiversity is genetic diversity. For geneticists, biodiversity is the diversity of genes and organisms. They study processes such as mutations, gene exchanges, and genome dynamics that occur at the DNA level and generate evolution.

For biologists, biodiversity is the gamut of organisms and species and their interactions. Organisms appear and become extinct; sites are colonized and some species develop social organizations to improve their varied strategies of reproduction.

For ecologists, biodiversity is also the diversity of durable interactions among species. It not only applies to species, but also to their immediate environment (biotope) and their larger ecoregion. In each ecosystem, living organisms are part of a whole, interacting with not only other organisms, but also with the air, water, and soil that surround them.

Measurement of biodiversity

Main article: diversity index

Biodiversity is a broad concept, so a variety of objective measures have been created in order to empirically measure biodiversity. Each measure of biodiversity relates to a particular use of the data.

For practical conservationists, this measure should quantify a value that is broadly shared among locally affected people. For others, a more economically defensible definition should allow the ensuring of continued possibilities for both adaptation and future use by people, assuring environmental sustainability.

As a consequence, biologists argue that this measure is likely to be associated with the variety of genes. Since it cannot always be said which genes are more likely to prove beneficial, the best choice for conservation is to assure the persistence of as many genes as possible. For ecologists, this latter approach is sometimes considered too restrictive, as it prohibits ecological succession.

Biodiversity is usually plotted as taxonomic richness of a geographic area, with some reference to a temporal scale. Whittaker[4] described three common metrics used to measure species-level biodiversity, encompassing attention to species richness or species evenness:

There are three other indices which are used by ecologists:

  • Alpha diversity refers to diversity within a particular area, community or ecosystem, and is measured by counting the number of taxa within the ecosystem (usually species)
  • Beta diversity is species diversity between ecosystems; this involves comparing the number of taxa that are unique to each of the ecosystems.
  • Gamma diversity is a measure of the overall diversity for different ecosystems within a region.

Distribution of biodiversity

Biodiversity is not distributed evenly on Earth. It is consistently richer in the tropics. As one approaches polar regions one finds fewer species. Flora and fauna vary depending on climate, altitude, soils and the presence of other species. For a listing of distinct ecoregions. In the year 2006 large numbers of the Earth's species are formally classified as rare or endangered or threatened species; moreover, most scientists estimate that there are millions more species actually endangered which simply have not been formally recognized.

A biodiversity hotspot is a region with a high level of endemic species. These biodiversity hotspots were first identified by Dr. Norman Myers in two articles in the scientific journal The Environmentalist (1988 and 1990). Hotspots unfortunately tend to occur near areas of dense human habitation, leading to threats to their many endemic species. As a result of the pressures of the rapidly growing human population, human activity in many of these areas is increasing dramatically. Most of these hotspots are located in the tropics and most of them are forests.

For example, Brazil's Atlantic Forest contains roughly 20,000 plant species, 1350 vertebrates, and millions of insects, about half of which occur nowhere else in the world. The Madagascar dry deciduous forests and lowland rainforests possess a very high ratio of species endemism and biodiversity, arising from the fact that this island separated from mainland Africa 65 million years ago.

Many regions of high biodiversity (as well as high endemism) arise from very specialized habitats which require unusual adaptation mechanisms. For example the peat bogs of Northern Europe and the alvar regions such as the Stora Alvaret on Oland, Sweden host a large diversity of plants and animals, many of whom are not found elsewhere.

Biodiversity and evolution

Phanerozoic Biodiversity

Apparent marine fossil diversity during the Phanerozoic

Biodiversity found on Earth today is the result of 4 billion years of evolution. The origin of life is not well known to science, though limited evidence suggests that life may already have been well-established only a few 100 million years after the formation of the Earth. Until approximately 600 million years ago, all life consisted of bacteria and similar single-celled organisms.

The history of biodiversity during the Phanerozoic (the last 540 million years), starts with rapid growth during the Cambrian explosion—a period during which nearly every phylum of multicellular organisms first appeared. Over the next 400 million years or so, global diversity showed little overall trend, but was marked by periodic, massive losses of diversity classified as mass extinction events.

The apparent biodiversity shown in the fossil record suggests that the last few million years include the period of greatest biodiversity in the Earth's history. However, not all scientists support this view, since there is considerable uncertainty as to how strongly the fossil record is biased by the greater availability and preservation of recent geologic sections. Some (e.g. Alroy et al. 2001) argue that corrected for sampling artifacts, modern biodiversity is not much different from biodiversity 300 million years ago. [5] Estimates of the present global macroscopic species diversity vary from 2 million to 100 million species, with a best estimate of somewhere near 10 million.

Most biologists agree however that the period since the emergence of humans is part of a new mass extinction, the Holocene extinction event, caused primarily by the impact humans are having on the environment. At present, the number of species estimated to have gone extinct as a result of human action is still far smaller than are observed during the major mass extinctions of the geological past. However, it has been argued that the present rate of extinction is sufficient to create a major mass extinction in less than 100 years. Others dispute this and suggest that the present rate of extinctions could be sustained for many thousands of years before the loss of biodiversity matches the more than 20% losses seen in past global extinction events.

New species are regularly discovered (on average about three new species of birds each year) and many, though discovered, are not yet classified (an estimate states that about 40% of freshwater fish from South America are not yet classified). Most of the terrestrial diversity is found in tropical forests.

Benefits of biodiversity

There are a multitude of benefits of biodiversity in the sense of one diverse group aiding another such as:

Food and drink

Biodiversity provides food for humans. About 80 percent of our food supply comes from just 20 kinds of plant. Although many kinds of animal are utilised as food, again most consumption is focused on a few species.

There is vast untapped potential for increasing the range of food products suitable for human consumption.

Medicines

A significant proportion of drugs are derived, directly or indirectly, from biological sources. However, only a small proportion of the total diversity of plants has been thoroughly investigated for potential sources of new drugs.

Industrial materials

A wide range of industrial materials are derived directly from biological resources. These include building materials, fibres, dyes, resins, gums, adhesives, rubber and oil. There is enormous potential for further research into sustainably utilising materials from a wider diversity of organisms.

Ecological services

Biodiversity provides many services that we take for granted. It plays a part in regulating the chemistry of our atmosphere and water supply. It is directly involved in recycling nutrients and providing fertile soils. Experiments with controlled environments have shown that we cannot easily build ecosystems to support ourselves.

Leisure, cultural and aesthetic value

Many people derive value from biodiversity through leisure activities such as enjoying a walk in the countryside, birdwatching or natural history programmes on television.

Biodiversity has inspired musicians, painters, sculptors, writers and other artists. Many cultural groups view themselves as an integral part of the natural world and show respect for other living organisms.

Threats to biodiversity

During the last century, erosion of biodiversity has been increasingly observed. Some studies show that about one of eight known plant species is threatened with extinction. Some estimates put the loss at up to 140,000 species per year (based on Species-area theory) and subject to discussion[6]. This figure indicates unsustainable ecological practices, because only a small number of species come into being each year. Most of the species extinctions from 1000 AD to 2000 AD are due to human activities, in particular destruction of plant and animal habitats. Almost all scientists acknowledge that the rate of species loss is greater now than at any time in human history, with extinctions occurring at rates hundreds of times higher than background extinction rates.

Elevated rates of extinction are being driven by human consumption of organic resources, especially related to tropical forest destruction[7]. While most of the species that are becoming extinct are not food species, their biomass is converted into human food when their habitat is transformed into pasture, cropland, and orchards. It is estimated that more than 40% of the Earth's biomass is tied up in only the few species that represent humans, our livestock and crops. Because an ecosystem decreases in stability as its species are made extinct, these studies warn that the global ecosystem is destined for collapse if it is further reduced in complexity. Factors contributing to loss of biodiversity are: overpopulation, deforestation, pollution (air pollution, water pollution, soil contamination) and global warming or climate change, driven by human activity. These factors, while all stemming from overpopulation, produce a cumulative impact upon biodiversity.

Some characterize loss of biodiversity not as ecosystem degradation but by conversion to trivial standardized ecosystems (e.g., monoculture following deforestation). In some countries lack of property rights or access regulation to biotic resources necessarily leads to biodiversity loss (degradation costs having to be supported by the community).

The widespread introduction of exotic species by humans is a potent threat to biodiversity. When exotic species are introduced to ecosystems and establish self-sustaining populations, the endemic species in that ecosystem, that have not evolved to cope with the exotic species, may not survive. The exotic organisms may be either predators, parasites, or simply aggressive species that deprive indigenous species of nutrients, water and light. These exotic or invasive species often have features due to their evolutionary background and environment that makes them very competitive, and similarly makes endemic species very defenceless and/or uncompetitive against these exotic species.

The rich diversity of unique species across many parts of the world exist only because they are separated by barriers, particularly seas and oceans, from other species of other land masses, particularly the highly fecund, ultra-competitive, generalist "super-species". These are barriers that could never be crossed by natural processes, except for many millions of years in the future through continental drift. However humans have invented ships and aeroplanes, and now have the power to bring into contact species that never have met in their evolutionary history, and on a time scale of days, unlike the centuries that historically have accompanied major animal migrations. As a consequence of the above, if humans continue to combine species from different ecoregions, there is the potential that the world's ecosystems will end up dominated by a very few, aggressive, cosmopolitan "super-species".

Biodiversity management: conservation, preservation and protection

Template:Mainarticle The conservation of biological diversity has become a global concern. Although not everybody agrees on extent and significance of current extinction, most consider biodiversity essential. There are basically two main types of conservation options, in-situ conservation and ex-situ conservation. In-situ is usually seen as the ideal conservation strategy. However, its implementation is sometimes unfeasible. For example, destruction of rare or endangered species' habitats sometimes requires ex-situ conservation efforts. Furthermore, ex-situ conservation can provide a backup solution to in-situ conservation projects. Some believe both types of conservation are required to ensure proper preservation. An example of an in-situ conservation effort is the setting-up of protection areas. Examples of ex-situ conservation efforts, by contrast, would be planting germplasts in seedbanks, or growing the Wollemi Pine in nurseries. Such efforts allow the preservation of large populations of plants with minimal genetic erosion.

At national levels a Biodiversity Action Plan is sometimes prepared to state the protocols necessary to protect an individual species. Usually this plan also details extant data on the species and its habitat. In the USA such a plan is called a Recovery Plan.

The threat to biological diversity was among the hot topics discussed at the UN World Summit for Sustainable Development, in hope of seeing the foundation of a Global Conservation Trust to help maintain plant collections.

Juridical status of biological diversity

Biodiversity must be evaluated and its evolution analysed (through observations, inventories, conservation...) then it must be taken into account in political decisions. It is beginning to receive a juridical setting.

  • "Law and ecosystems" relationship is very ancient and has consequences for biodiversity. It is related to property rights, private and public. It can define protection for threatened ecosystems, but also some rights and duties (for example, fishing rights, hunting rights).
  • "Laws and species" is a more recent issue. It defines species that must be protected because threatened by extinction. Some people question application of these laws. The U.S. Endangered Species Act is an example of an attempt to address the "law and species" issue.
  • "Laws and genes" is only about a century old. While the genetic approach is not new (domestication, plant traditional selection methods), progress made in the genetic field in the past 20 years lead to the obligation to tighten laws. With the new technologies of genetic and genetic engineering, people are going through gene patenting, processes patenting, and a totally new concept of genetic resource. A very hot debate today seeks to define whether the resource is the gene, the organism, the DNA or the processes.

The 1972 UNESCO convention established that biological resources, such as plants, were the common heritage of mankind. These rules probably inspired the creation of great public banks of genetic resources, located outside the source-countries.

New global agreements (e.g.Convention on Biological Diversity), now give sovereign national rights over biological resources (not property). The idea of static conservation of biodiversity is disappearing and being replaced by the idea of dynamic conservation, through the notion of resource and innovation.

The new agreements commit countries to conserve biodiversity, develop resources for sustainability and share the benefits resulting from their use. Under these new rules, it is expected that bioprospecting or collection of natural products has to be allowed by the biodiversity-rich country, in exchange for a share of the benefits.

Sovereignty principles can rely upon what is better known as Access and Benefit Sharing Agreements (ABAs). The Convention on Biodiversity spirit implies a prior informed consent between the source country and the collector, to establish which resource will be used and for what, and to settle on a fair agreement on benefit sharing. Bioprospecting can become a type of biopiracy when those principles are not respected.

Uniform approval for use of biodiversity as a legal standard has not been achieved, however. At least one legal commentator has argued that biodiversity should not be used as a legal standard, arguing that the multiple layers of scientific uncertainty inherent in the concept of biodiversity will cause administrative waste and increase litigation without promoting preservation goals. See Fred Bosselman, A Dozen Biodiversity Puzzles, 12 N.Y.U. Environmental Law Journal 364 (2004)

Criticisms of the biodiversity paradigm

Blue Linckia Starfish

Some of the biodiversity of a coral reef.

The founder effect

The field of biodiversity research has often been criticised for being overly defined by the personal interests of the founders (i.e. terrestrial mammals) giving a narrow focus, rather than extending to other areas where it could be useful. This is termed the founder effect by Norse and Irish, (1996)[8]. France and Rigg reviewed biodiversity research literature in 1998 and found that there was a significant lack of papers studying marine ecosystems[9], leading them to dub marine biodiversity research the sleeping hydra.

There was never any belief that biodiversity should be limited to terrestrial organisms, however. The inattention to marine biodiversity was due, rather, to the gigantic scale of such an endeavor and the need to focus in the immediate term on an area where existing techniques of preservation could be applied. The very much needed conservation of marine biodiversity involves having to pioneer new and international mechanisms of protection, as well as solving methodological problems about the classification of marine ecosystem types and data-gathering on some of the earth's most difficult species to assess and monitor.

Size bias

Biodiversity researcher Sean Nee, writing in the 24 June 2004 edition of Nature, points out that the vast majority of Earth's biodiversity is microbial, and that contemporary biodiversity physics is "firmly fixated on the visible world" (Nee uses "visible" as a synonym for macroscopic). For example, microbial life is very much more metabolically and environmentally diverse than multicellular life (see extremophile). Nee has stated: "On the tree of life, based on analyses of small-subunit ribosomal RNA, visible life consists of barely noticeable twigs. This should not be surprising — invisible life had at least three billion years to diversify and explore evolutionary space before the 'visibles' arrived".

The reply to this, however, is that biodiversity conservation has never focused exclusively on visible (in this sense) species. From the very beginning, the classification and conservation of natural communities or ecosystem types has been a central part of the effort. The thought behind this has been that since invisible (in this sense) diversity is, due to lack of taxonomy, impossible to treat in the same manner as visible diversity, the best that can be done is to preserve a diversity of ecosystem types, thereby preserving as well as possible the diversity of invisible orgainisms.

Notes

  1. Edward O.Wilson, editor, Frances M.Peter, associate editor, Biodiversity, National Academy Press, March 1988 ISBN 0-309-03783-2 ; ISBN 0-309-03739-5 (pbk.), online edition
  2. Global Biodiversity Assessment. UNEP, 1995, Annex 6, Glossary. ISBN 0-521-56481-6, used as source by "Biodiversity", Glossary of terms related to the CBD, Belgian Clearing-House Mechanism, retrieved April 26, 2006.
  3. Kevin J. Gaston & John I. Spicer. 2004. "Biodiversity: an introduction", Blackwell Publishing. 2nd Ed., , ISBN 1-4051-1857-1(pbk.)
  4. hittaker, R.H., Evolution and measurement of species diversity, Taxon, 21, 213-251 (1972)
  5. J. Alroy, C.R. et al.2001. Effect of sampling stanardization on estimates of Phanerozonic marine diversification. Proceedings of the National Academy of Science, USA 98: 6261-6266
  6. S.L. Pimm, G.J. Russell, J.L. Gittleman and T.M. Brooks, The Future of Biodiversity, Science 269: 347-350 (1995)
  7. Paul Ehrlich and Anne Ehrlich, Extinction, Random House, New York (1981) ISBN 0-394-51312-6
  8. Irish, K.E. and Norse, E.A. (1996) Scant emphasis on marine biodiversity Conserv. Biol. 10 680
  9. France, R., and Rigg, C. (1998) Examination of the 'founder effect' in biodiversity research: patterns and imbalances in the published literature Diversity and Distributions 4 77-86

See also

External links


Policies

Directories


Smallwikipedialogo.png This page uses content from Wikipedia. The original article was at Biodiversity. The list of authors can be seen in the page history. As with Paleontology Wiki, the text of Wikipedia is available under the GNU Free Documentation License.

Ad blocker interference detected!


Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers

Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.