Biological diversity is one of the most important, yet least widely understood natural resources on the planet. If one was to look at North America 400 or 500 years ago, long before European settlers started having an effect on the landscapes; one would see vast unbroken natural ecosystems. Each habitat consisting of endemic and diverse species well adapted to their environment with almost everything in sustainable balance. Clearly, this world is a thing of the past. Today, biological diversity is threatened by many things, the most important of which include habitat loss and fragmentation, the introduction of exotic species, over-exploitation of species, habitat pollution, and unsustainable agricultural practices. [1]

Habitat loss and fragmentation due to human encroachment has been on a steady increase for around 10,000 years, since the start of wide spread agricultural practices. Agricultural practices allowed humans to slowly change from a primarily hunter-gatherer species to a much more sedentary way of life. Eventually, agriculture leads to the development of large scale settlements and buildings, which eventually require infrastructure like roads to support them. The slow but sure division and partition of the natural world for human interests has severely affected biological diversity by essentially ruining habitat and seriously decreasing biodiversity. Examples of this include the often cited fact that �ninety-eight percent of the tropical� forest along Central America's Pacific coast [have] disappeared� [2] primarily because of the expansion of grazing land for cattle, causing extinction rates nearly 1000 times higher than normal background extinction. [3] In addition to complete destruction like this, fragmentation of habitats can have just as detrimental an effect, especially for predatory species. Many of these predators need relatively large hunting ranges that may need to include interior habitat, something that most fragments simply don�t have. [4] If patches of habitat are not connected by corridors which allow the free flow of species between patches (in effect, sharing biodiversity), the viability of those patch habitats is almost certainly minimal. One possible solution to the problem of habitat loss and fragmentation is to build networks of habitat reserves that are connected by corridors. Each individual patch would be just �big enough� to support the biological diversity desired, and the entire network could be quite large because human infrastructure and settlements could be interspersed between the fragments.

Another major threat to biodiversity is the introduction of exotic species into an ecosystem. When a species is transplanted, through whatever means, into a new ecosystem, there is a chance that that species will flourish. In some cases, the invasive species has a sort of �unfair� advantage over endemic species because of the lack of predators and competition that would be present in that species� home environment. Typically, invasive exotics are much more of a problem in North America than in most other parts of the world. This likely because most other parts of the world have been populated by agricultural (read: destructive) societies for many thousands of years, and therefore species there learned to quickly adapt to changes in their environment. North American species have had the �good life� for most of their existence, and so have a much harder time adapting to sudden change. Some examples of species that have become invasive in America are the Asian Longhorned Beetle, Gypsy Moth, English Ivy, and of course Purple Loosestrife. [5] These species, because of their resilience and lack of competition, tend to take over an ecosystem and destroy much of the natural biodiversity. The Asian Longhorned Beetle, for instance, attacks many hardwood tree species in several parts of North America. The beetles lay their eggs deep within the tree, and as they mature, they eat their way out of the tree, �eventually [weakening] the tree to the point that the tree literally falls apart and dies.� [6] These beetles do far less damage in China (where they originate) because most tree species there have developed both a tolerance and a resistance to the beetle through evolution, and the beetles have many natural predators. In order to prevent the damage caused by the introduction of invasive exotics, stringent precautions need to be taken when importing goods from other countries. The United States already regulates these imports to some extent, but not nearly enough to ensure reliable prevention. For the species that are currently here, campaigns to rid ecosystems of them should be promoted in the communities and areas effected. Grass roots (pun intended) efforts are key to the successful removal of such species.

The way most individuals, especially Americans, view the environment is as a resource. Much of this has to do with religious beliefs rooted deep within the culture, as well as beliefs centered on western-style ideologies, which often dictate that the mastery of nature is preferable to working within it. [7] As a result, over exploitation of species is a major threat to biological diversity on a global scale. It is possible to exploit a natural resource without causing harm. Over exploitation, however, often depletes the biodiversity in a species or group of species to the point where it is no longer a biologically viable population, or is no longer sufficient in physical size to allow for the continuation of that species. A good example of this is the story of the passenger pigeon. The passenger pigeon was once so large in numbers that it would darken the skies during single flock migrations, which would often contain tens of millions of individual pigeons. In fact at one point the passenger pigeon was the single most plentiful species of bird in all of North America. [8] The last known passenger pigeon died in captivity in 1914, joining the countless billions before her that had died at the hands of millions of sport hunters. [9] Passenger pigeons were hunted for sport for only about 50 years, but during that time the entire species was exterminated simply by over exploitation. This unfortunate pigeon is one of many examples of over exploitation of a species, with others including the whaling of the Humpback, over fishing of fisheries like the Grand Banks, and deforestation like that in the Amazon. Options for fighting over exploitation aren�t as obvious as they might seem. Many suggest government control and regulation, and while this may work to some extent, education of those doing the exploiting as to the purpose of preserving that resource works much better in the long run.

Along the same lines as over exploitation, many industrialized nations have historically not been very concerned with what byproducts of industry are released back into the environment. Much of the damage caused by many pollutants is due to the compounding affects of food chains in ecosystems. Typically, the creatures most directly impacted by the pollutants, such toxic waste released into a river or stream, are those species which are at the base of the food chain. These indicator species, such as water dwelling macroinvertebrates and amphibians or soil dwelling bacteria, often are the first to go. The damage does not stop there, however, as those species serve both as a food source for many higher level species, but also in many cases as the keystone species in that system. To give a poignant example, the majority of the world�s oxygen is created by photosynthetic algae living at or near the surface of the ocean. [10] This alga is extremely sensitive to pollution, and the affects of a disruption of this vital process would have catastrophic consequences world wide. Granted, this is an extreme example, but extreme only in its scale. This kind of disruption happens constantly in smaller ecosystems because of pollution. Examples such as acid rain in the Adirondacks [11] , and the destruction of thousands of acres of forest in Europe due to air pollution will become more common as 3^rd world countries begin to develop. To help slow this destruction countries with the means to both clean up pollution and curtail it with regulations would greatly help preserve biodiversity if they do so.

Lastly, unsustainable agricultural practices are one of the single largest sources of the loss of biodiversity that exists today, and as the world population continues to climb, it is only likely to increase. As previously mentioned, the rise of the agricultural society around 10,000 years ago increased the impacts humans have on the environment drastically. Agriculture, which includes crop production and the management of livestock, is responsible for consuming some of the most biologically rich ecosystems in the world. Almost half the of 17,000 reserves setup to preserve biological diversity are currently being used for agricultural purposes. [12] Cattle ranching in Brazil is responsible for almost 80% of all clear cutting of the Amazonian tropical rain forest, one of the most biological rich areas on the planet. [13] In addition to the problems associated with the use of land for agriculture, the way farms are traditionally run is also extremely detrimental to biological diversity. Farms are primarily monoculture environments which use heavy levels of pesticides and herbicides to control the insect and weed populations. The over use of these techniques causes pollution via agricultural run off, the direct destruction of countless species in and around the fields being sprayed, and the eventual development of resistant species which would lead to increased use of different, potentially more potent chemical controls. Aside from straight government regulation and education, both of which can be affective, there is great promise in the use of transgenic technology in agriculture. A transgenic corn, for instance, could be engineered to both repel insects and fixate nitrogen in the soil. This could lead to far less land and pesticide use, thereby increasing biological diversity for the reasons already stated. There are many problems with transgenic technology, but with proper regulation, it holds great promise for the future of agriculture.

The world has seen 5 major extinctions since life developed nearly 4 billion years ago [14] , and there is a great deal of evidence that Earth is currently undergoing the 6^th major extinction [15] . In order to stop this extinction humanity must be convinced it is the right thing to do. To achieve this it is important to realize there are two ways to look at the problem. There is a moral imperative for preserving biodiversity, building off the idea that humanity has an obligation to protect life on Earth from excessive damaged caused by humans, but this is not the only reason, although it is often the reason cited by environmentalists. Morality is relative and often has strong ties to religion, causing many to ignore or dismiss moral arguments that contradict traditions taught by their religion. In order to prevent the sixth extinction it is crucial to point out the selfish reasons, reasons that everybody can agree on, for preserving biodiversity. Preserving biological diversity is essential for maintaining both our morality, and our survival.

Western civilization is primarily a Judeo-Christian society, a society which believes �that the world and its living creatures were placed there by the Creator for� [16] utilization and exploitation. While this is not the only cause of the 6^th extinction, not having a moral basis on which to justify the destruction of the natural world would certainly help slow current trends. One of the first people to suggest an ethical and moral obligation to the preservation of biodiversity was Aldo Leopold. In his now renowned book, A Sand County Almanac, Leopold promoted a �startlingly innovative idea, called the �land ethic�,� [17] which explained that nature was not simply there for use and exploitation, but instead had inherent and intrinsic value, and people should �live with greater reverence for its ability to support all manner of life.� [18] Preserving nature through adherence to a �land ethic� was, and is, a major contradiction to Judeo-Christian (western) values. Nonetheless, Leopold essentially started the first major environmental revolution, albeit not until long after he died in 1948, showing that people can indeed change their tenets if educated. In addition, while �Genesis specifically exhorts humans to seek dominion over [nature],� many biblical scholars and theologians suggest that this is in fact �a call to stewardship.� [19] This fits in quite well with Leopold�s �land ethic,� which does not suggest that nature should be left entirely alone, as most people realize that it would be impossible to live within nature without having some effect on it. Instead, Leopold encourages management and appreciation of biodiversity rather than simple exploitation. The idea of a �land ethic� needs to be central to any strategy to convince people that it is humanity�s moral responsibility to preserve biological diversity. Through education and experience, people can learn the non-utilitarian values of nature, and will therefore be much less likely to destroy it.

Morality and ethics certainly play a pivotal role in the fight against the 6^th extinction, but in order to be truly affective any educational or voluntary solution (as apposed to enforced regulation) must utilize one of the strongest motivational forces in existence: self preservation. Selfishness is, by definition, simply a symptom of this self preservative force. Richard Dawkins, in his acclaimed book The Selfish Gene, explains that �the predominant quality to be expected in a successful gene is ruthless selfishness,� which leads him to the conclusion that this �will usually give rise to selfishness in individual behavior.� [20] The preservation of biological diversity does not seem at first glance to fit in with this ultimate evolutionary selfishness. Why should an individual preserve others at cost to itself? Upon closer examination of the reasoning behind the preservation of biodiversity, however, it is clear that while it may have short term costs, the long term costs of not preserving the biological resources of the world are far greater. Countless human endeavors, such as agriculture, industry, and technological progress all come at the expense of the natural world. Because of the interconnected nature of ecosystems, landscapes, and the entire biosphere any damage humanity causes to that system will certainly come back to haunt it. Many examples of both the loss of a potentially valuable resource, such as plants of medicinal value in many clear cut tropical rain forests [21] , and reciprocal damaged due to habitat destruction or pollution, such as the loss of sea algae that provide more than half of the planet�s oxygen [22] , are easily explained to those that will listen. If people are aware of the reasons why conservation biologists and environmentalists insist on saving ecosystems and protecting biodiversity, many will realize that it is in their own or their children�s interest to not by that SUV or not use that pesticide on their crops.

One could argue that humanity is only acting according to its biology, utilizing resources to further individual existence. Dawkins would undoubtedly respond with another conceptual idea also detailed in The Selfish Gene. Dawkins suggests that while selfishness is a trait inherent in individuals to preserve the genes that the individual carries (a result of evolution, with the more �selfish� genes tending to survive and pass on that trait), the survival of a gene or set of genes does not usually rely on one individual. Acts of altruism on the part of the individual, which seemingly contradict the selfish principal on which Dawkin�s argument is based, are actually examples of an individual sacrificing to preserve a population of genes, in this case a species. [23] Perhaps one of the evolutionary benefits of the intelligence that has evolved in humanity over millions of years is that it lets us have the ability to see the dangers associated with the unparalleled control we can assert over the natural world, and thereby realize it is in our interest to preserve that biological diversity. In other words, no matter how one looks at the preservation of biological diversity, it makes evolutionary sense to do so. Hopefully, a combination of biology and education will help make people realize that the many destructive activities humans take part in are as logically wrong as they are morally wrong.

At the very least, people should prevent the 6^th extinction if for no other reason than we are the ones causing it.

Works Cited

Roach, Joan. (2001) Fear of Snakes, Spiders Rooted in Evolution, Study Finds. National Geographic News. National Geographic. Retrieved November 12^th, 2001 from the World Wide Web:
http://news.nationalgeographic.com/news/2001/10/1004_snakefears.html

Extinction-Prone Groups of Species. (1989) World Resource Institute. Retrieved November 12^th, 2001 from the World Wide Web:
http://www.igc.org/wri/biodiv/b04-koa.html

Kramer, Randall; Schaik, Carel van; Johnson, Julie. (1997) Last Stand: Protected � Areas and the Defense of Tropical Biodiversity. Oxford University Press. New York. Retrieved November 12^th, 2001 from the World Wide Web:
http://wildlife.wisc.edu/courses/360a/discuss/LastStandCh1.html

Wildlife 'Corridors' Save Species from 'Islands' of Habitat. (1997) California Biodiversity News. Fall - Vol. 5, No. 1. Retrieved November 12^th, 2001 from �the World Wide Web:
http://ceres.ca.gov/biodiversity/newsletter/v5n1/wildlife_corridors.html

Sovada, Marsha A; Zicus, Michael C; Greenwood, Raymond J; Rave, David P; Newton, Wesley E; Woodward, Robert O; Beiser, Julia A. Relationships of ���� Habitat Patch Size to Predator Community and Survival of Duck Nests. Northern Prairie Wildlife Research Center. USGS. Retrieved November 12^th, �2001 from the World Wide Web:
http://www.npwrc.usgs.gov/resource/2000/habpatch/habpatch.htm

Mechanisms for the Loss of Biodiversity. World Resource Institute. Retrieved November 12^th, 2001 from the World Wide Web:
http://www.igc.org/wri/biodiv/b05-gbs.html

Sternlof, Kurt. (2000) Tropical Habitat Loss Threatens Mass Extinction Akin To Fall of the Dinosaurs. Columbia University News. March. Retrieved November ��� 13^th, 2001 from the World Wide Web:
http://www.columbia.edu/cu/pr/00/03/extinction.html

Major, Richard. Habitat Fragmentation, its Effect on Biodiversity. Australian Museum Fact Sheets. Australian Museum Online. Retrieved November 13^th, 2001 from the World Wide Web:
http://www.amonline.net.au/factsheets/habitat_fragmentation.htm

Invasive Exotic Species. (2001) Invasive.org. The Bugwood Network. University ��� of Georgia. Retrieved November 13^th, 2001 from the World Wide Web:
http://www.invasive.org/

Meyer, Dana A. (1998) Special Report: Asian Longhorned Beetle. Bugwood.org. The Bugwood Network. University of Georgia. Retrieved November 13^th, 2001 from the World Wide Web:
http://www.gacaps.org/pests/albfact.html

Eldredge, Niles. (1998) Life in the Balance. Princeton University Press. Princeton, NJ.

How Biological Diversity is Lost. Society for Conservation Biology. Aldo Leopold Chapter. Retrieved November 14^th, 2001 from the World Wide Web:
http://www.ies.wisc.edu/partners/ALC-SCB/wiscbiod/bd-loss.htm

Schenk, Tony. The Passenger Pigeon. Retrieved November 14^th, 2001 from the World Wide Web:
http://www.ris.net/~tony/ppigeon.html

Miracle of the Blue Green Algae. Retrieved November 14^th, 2001 from the World Wide Web:
http://www.millenium2.org/sbgaart/sbgahist.htm

Higgins, Margot. (2001) Agriculture Eats Away at Biodiversity. Environmental News Network. Retrieved November 14^th, 2001 from the World Wide Web:
http://www.enn.com/news/enn-stories/2001/05/05102001/agric_43434.asp

The Destruction of the Amazon Rain Forest. Sherwood Heights. Elk Island �Schools. Retrieved November 14^th, 2001 from the World Wide Web:
http://www.ei.educ.ab.ca/sch/sht/Destruction-Rain-Forest.html

Horgan, John. (1996) Life, Life Everywhere. Scientific American. Retrieved November 14^th, 2001 from the World Wide Web:
http://www.sciam.com/explorations/112596explorations.html

Leakey, Richard; Lewin, Roger. (1995) The Sixth Extinction. Doubleday Press. Retrieved November 14^th, 2001 from the World Wide Web:
http://www.well.com/user/davidu/sixthextinction.html

Profiles in Conservation: Aldo Leopold. (1998) The Wilderness Annual. Retrieved November 14^th, 2001 from the World Wide Web:
http://www.wilderness.org/profiles/leopold.htm

Dawkins, Richard. (1989) The Selfish Gene. Oxford University Press. Oxford. New York.

Deforestation of Tropical Rain Forests. (1998) Rain Forest Report Card. Basic Science and Remote Sensing Initiative. Michigan State University. Retrieved �� November 14^th, 2001 from the World Wide Web:
http://www.bsrsi.msu.edu/rfrc/status.html