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Biodiversity and Human Life
Contemporary societies that live close to the land often have a broad knowledge of the medicinal uses of plants growing in their area.
Most plants produce secondary plant compounds, which are toxins used to protect the plant from insects and other animals that eat them, but some of which also work as medication. For centuries in Europe, knowledge about the medical uses of plants was compiled in herbal-books. Humans are not the only species to use plants for medicinal reasons: orangutans, chimpanzees, and gorillas have all been observed self-medicating with plants.
Modern pharmaceutical science also recognizes the importance of plant compounds. Examples of significant medicines derived from plant compounds include aspirin, codeine, digoxin, atropine, and vincristine. Many medicines were once derived from plant extracts but are now synthesized. It is estimated that, at one time, 25 percent of modern drugs contained at least one plant extract. That number has probably decreased to about 10 percent as natural plant ingredients are replaced by synthetic versions.
Antibiotics, which are responsible for improvements in health and lifespans in developed countries, are compounds largely derived from fungi and bacteria.
In recent years, animal venoms and poisons have excited intense research for their medicinal potential.
By 2007, the Federal Drug Administration in the US had approved five drugs based on animal toxins to treat diseases such as hypertension, chronic pain, and diabetes. Another five drugs are undergoing clinical trials, and at least six drugs are being used in other countries. Other toxins under investigation come from snakes, lizards, amphibians, fish, and scorpions.
Aside from representing billions of dollars
in profits, these medicines improve people’s
lives. Pharmaceutical companies are actively
looking for new compounds synthesized by
living organisms that can function
It is estimated that 1/3 of pharmaceutical
research and development is spent on natural compounds and that about 35 percent of new drugs brought to market between 1981 and 2002 were from natural compounds.
The opportunities for new medications will be reduced in direct proportion to the disappearance of species.
Since the beginning of human agriculture more than 10,000 years ago, human groups have been breeding and selecting crop varieties. This crop diversity matched the cultural diversity of highly subdivided populations of humans.
For example, potatoes were domesticated beginning around 7,000 years ago in the central Andes of Peru and Bolivia. The potatoes grown in that region belong to seven species and the number of varieties likely is in the thousands. Each variety has been bred to thrive at particular elevations and soil and climate conditions.
The potato demonstrates a well-known example of the risks of low crop diversity:
the tragic Irish potato famine when the single variety grown in Ireland became susceptible to a potato blight, wiping out the crop.
The loss of the crop led to famine, death, and mass emigration. Resistance to disease is a chief benefit to maintaining crop biodiversity, and lack of diversity in crop species carries similar risks.
Diversity is driven by the diverse demands of the topography, the limited movement of people, and the demands created by crop rotation for different varieties that will do well in different fields.
Potatoes are only one example of human-generated diversity. Every plant, animal, and fungus that has been cultivated by humans has been bred from original wild ancestor species into diverse varieties arising from the demands for food value, adaptation to growing conditions, and resistance to pests.
Seed companies, which are the source of most crop varieties in developed countries, must continually breed new varieties to keep up with evolving pest organisms.
These same seed companies, however, have participated in the decline of the number of varieties available as they focus on selling fewer varieties in more areas of the world. The ability to create new crop varieties relies on the diversity of varieties available and the accessibility of wild forms related to the crop plant. These wild forms are often the source of new gene variants.
Loss of wild species related to a crop will mean the loss of potential in crop improvement. Maintaining the genetic diversity of wild species related to domesticated species ensures our continued food supply.
Since the 1920s, government agriculture departments have maintained seed banks of crop varieties as a way to maintain crop diversity. This system has flaws because over time seed banks are lost through accidents, and there is no way to replace them. In 2008, the Svalbard Global Seed Vault began storing seeds from around the world as a backup system to the regional seed banks.
The seed vault is located deep in the rock of an arctic island. Conditions within the vault are maintained at ideal temperature and humidity for seed survival, but the deep underground location of the vault in the arctic means that failure of the vault’s systems will not compromise the climatic conditions inside the vault.
Crops are not grown, for the most part, in built environments. They are grown in soil.
Although some agricultural soils are rendered sterile using controversial cultivation and chemical treatments, most contain a huge diversity of organisms that maintain nutrient cycles, breaking down organic matter into nutrient compounds that crops need for growth. These organisms also maintain soil texture that affects water and oxygen dynamics in the soil that are necessary for plant growth.
If farmers had to maintain arable soil using
alternate means, the cost of food would be
much higher than it is now.
These kinds of processes are called ecosystem
They occur within ecosystems, such as soil
ecosystems, as a result of the diverse metabolic
activities of the organisms living there, but they
provide benefits to human food production,
drinking water availability, and breathable air.
Other key ecosystem services related to food production are plant pollination and crop pest control.
Over 150 crops in the United States require pollination to produce.
One estimate of the benefit of honeybee pollination within the United States is $1.6 billion per year; other pollinators contribute up to $6.7 billion more.
Many honeybee populations are managed by apiarists who rent out their hives’ services to farmers. Honeybee populations in North America have been suffering large losses caused by a syndrome known as colony collapse disorder, whose cause is unclear.
Other pollinators include a diverse array of other bee species and various insects and birds. Loss of these species would make growing crops requiring pollination impossible, increasing dependence on other crops.
Humans compete for their food with crop pests, most of which are insects.
Pesticides control these competitors; however, pesticides are costly and lose their effectiveness over time as pest populations adapt.
They also lead to collateral damage by killing non-pest species and risking the health of consumers and agricultural workers.
Ecologists believe that the bulk of the work in removing pests is actually done by predators and parasites of those pests, but the impact has not been well studied.
A review found that in 74 percent of studies that looked for an effect of landscape complexity on natural enemies of pests, the greater the complexity, the greater the effect of pest-suppressing organisms.
An experimental study found that introducing multiple enemies of pea aphids (an important alfalfa pest) increased the yield of alfalfa significantly.
This study shows the importance of landscape diversity via the question of whether a diversity of pests is more effective at control than one single pest; the results showed this to be the case.
In addition to growing crops and raising animals for food, humans obtain food resources from wild populations, primarily fish populations.
For approximately 1 billion people, aquatic resources provide the main source of animal protein. But since 1990, global fish production has declined. Despite considerable effort, few fisheries on the planet are managed for sustainability. Fishery extinctions rarely lead to complete extinction of the harvested species, but rather to a radical restructuring of the marine ecosystem in which a dominant species is so over-harvested that it becomes a minor player, ecologically.
In addition to humans losing the food source,
these alterations affect many other species in
ways that are difficult or impossible to predict.
The collapse of fisheries has dramatic and
long-lasting effects on local populations that
work in the fishery. In addition, the loss of an
inexpensive protein source to populations that
cannot afford to replace it will increase the cost
of living and limit societies in other ways.
In general, the fish taken from fisheries have shifted to smaller species as larger species are fished to extinction. The ultimate outcome could clearly be the loss of aquatic systems as food sources.
Finally, it has been argued that humans benefit psychologically from living in a biodiverse world.
A chief proponent of this idea is entomologist E. O. Wilson.
He argues that human evolutionary history has adapted us to live in a natural environment and that built environments generate stressors that affect human health and well-being. There is considerable research into the psychological regenerative benefits of natural landscapes that suggests the hypothesis may hold some truth. In addition, there is a moral argument that humans have a responsibility to inflict as little harm as possible on other species.
adaptive radiation rapid branching through speciation of a phylogenetic tree into many closely related species
biodiversity hotspot concept originated by Norman Myers to describe a geographical region with a large number of endemic species and a large percentage of degraded habitat
biodiversity variety of a biological system, typically conceived as the number of species, but also applying to genes, biochemistry, and ecosystems
bush meat wild-caught animal used as food (typically mammals, birds, and reptiles); usually referring to hunting in the tropics of sub-Saharan Africa, Asia, and the Americas
chemical diversity variety of metabolic compounds in an ecosystem
chytridiomycosis disease of amphibians caused by the fungus Batrachochytrium dendrobatidis; thought to be a major cause of the global amphibian decline
DNA barcoding molecular genetic method for identifying a unique genetic sequence to associate with a species
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