1) Biodiversity refers to the variety of species that exist on Earth and the ecosystems they inhabit. Scientists estimate there are over 10 million species but some suggest over 100 million. 2) Each species is uniquely adapted to its ecological niche. Biodiversity underlies food, medicine, shelter and clothing for humans worldwide. 3) The rate of species extinction is estimated to be 27,000 per year, the sixth mass extinction in Earth's history. The primary cause is human destruction of natural habitats and ecosystems through activities like agriculture, urbanization, and infrastructure development.

1. BiodiversityDomingo R. BaldovinoPresenter/DiscussantProfessor: Jo. B. Bitonio, DPACognate on Environmental Issues & Problems with Emphasis on Ecology1st Semester 2011Graduate School, PSU, Urdaneta City

2. BiodiversityBiodiversity is the sum of all the different species of animals, plants, fungi, and microbial organisms living on Earth and the variety of habitats in which they live. Scientists estimate that upwards of 10 million—and some suggest more than 100 million—different species inhabit the Earth.

3. BiodiversityEach species is adapted to its unique niche in the environment, from the peaks of mountains to the depths of deep-sea hydrothermal vents, and from polar ice caps to tropical rain forests.

4. BiodiversityBiodiversity underlies everything from food production to medical research. Humans the world over use at least 40,000 species of plants and animals on a daily basis.Many people around the world still depend on wild species for some or all of their food, shelter, and clothing

5. All of our domesticated plants and animals came from wild-living ancestral species. Close to 40 percent of the pharmaceuticals used in the United States are either based on or synthesized from natural compounds found in plants, animals, or microorganisms.

6. The array of living organisms found in a particular environment together with the physical and environmental factors that affect them is called an ecosystem. Healthy ecosystems are vital to life: They regulate many of the chemical and climatic systems that make available clean air and water and plentiful oxygen.

7. BiodiversityForests, for example, regulate the amount of carbon dioxide in the air, produce oxygen as a byproduct of photosynthesis (the process by which plants convert energy from sunlight into carbohydrate energy), and control rainfall and soil erosion. Ecosystems, in turn, depend on the continued health and vitality of the individual organisms that compose them. Removing just one species from an ecosystem can prevent the ecosystem from operating optimally.

8. Global Biodiversity CrisisMost biologists accept the estimate of American evolutionary biologist Edward O. Wilson that the Earth is losing approximately 27,000 species per year.This estimate is based primarily on the rate of disappearance of ecosystems, especially tropical forests and grasslands, and our knowledge of the species that live in such systems.

9. Biodiversity CrisisWe can measure the rate of loss of tropical rain forests, for example, by analyzing satellite photographs of continents from different periods that show rates and amounts of habitat destruction—and from these measurements calculate the approximate number of species being lost each year.

10. Biodiversity CrisisThis extraordinary rate of extinction has occurred only five times before in the history of complex life on Earth. Mass extinctions of the geological past were caused by catastrophic physical disasters, such as climate changes or meteorite impacts, which destroyed and disrupted ecosystems around the globe.

11. Biodiversity CrisisIn the fifth mass extinction, which occurred more than 65 million years ago, the Earth was shrouded in a cloud of atmospheric dust—the result of meteorite impact or widespread volcanic activity. The resulting environmental disruption caused the demise of 76 percent of all species alive at the time, including the dinosaurs.

12. Biodiversity CrisisToday’s sixth extinction is likewise primarily caused by ecosystem disturbance—but this time the destroying force is not the physical environment, but rather humankind. The human transformation of the Earth's surface threatens to be every bit as destructive as any of the past cataclysmic physical disasters.

13. Human ImpactThe underlying cause of biodiversity loss is the explosion in human population, now at 6 billion, but expected to double again by the year 2050. The human population already consumes nearly half of all the food, crops, medicines, and other useful items produced by the Earth’s organisms, and more than 1 billion people on Earth lack adequate supplies of fresh water. But the problem is not sheer numbers of people alone: The unequal distribution and consumption of resources and other forms of wealth on the planet must also be considered.

14. Human ImpactThe single greatest threat to global biodiversity is the human destruction of natural habitats. Since the invention of agriculture about 10,000 years ago, the human population has increased from approximately 5 million to a full 6 billion people. During that time, but especially in the past several centuries, humans have radically transformed the face of planet Earth.

15. Human ImpactThe conversion of forests, grasslands, and wetlands for agricultural purposes, coupled with the multiplication and growth of urban centers and the building of dams and canals, highways, and railways, has physically altered ecosystems to the point that extinction of species has reached its current alarming pace.

16. Preserving BiodiversityAs the scope and significance of biodiversity loss become better understood, positive steps to stem the tide of the sixth extinction have been proposed and, to some extent, adopted. Several nations have enacted laws protecting endangered wildlife. An international treaty known as the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) went into effect in 1975 to outlaw the trade of endangered animals and animal parts. The Convention on Biological Diversity, held in Rio de Janeiro, Brazil, in 1992 and ratified by more than 160 countries, obligates governments to take action to protect plant and animal species.

17. Preserving BiodiversityIn the last three decades, focus has shifted away from the preservation of individual species to the protection of large tracts of habitats linked by corridors that enable animals to move between the habitats. Thus the movement to save, for example, the spotted owl of the Pacific Northwest, has become an effort to protect vast tracts of old-growth timber.

18. Preserving BiodiversityPromising as these approaches may be, conservation efforts will never succeed in the long run if the local economic needs of people living in and near threatened ecosystems are not taken into account. This is particularly true in developing countries, where much of the world’s remaining undisturbed land is located.

19. Preserving BiodiversityAt the end of the 20th century, international organizations such as the World Bank and the World Wildlife Fund launched a movement for all countries in the developing world to set aside 10 percent of their forests in protected areas. But many communities living near these protected areas have relied on the rain forest for food and firewood for thousands of years. Left with few economic alternatives, these communities may be left without enough food to eat.