The Value of Biodiversity

¨       Biodiversity is the sum total of the genetically based variety of all organisms in the biosphere.

¨       Ecosystem diversity includes the variety of habitats, communities, and ecological processes in the living world.

¨       Species diversity refers to the number of different species in the biosphere.

Ø       Biologists have identified and named 1.5 million species and millions more may be discovered.

¨       Genetic diversity refers to the sum total of all the different forms of genetic information carried by all organisms living on Earth today.

¨       Biodiversity is one of Earth’s greatest natural resources.

¨       Species of many kinds have provided us with:

¨       Foods

¨       Industrial products

¨       Medicines (painkillers, antibiotics, heart drugs, antidepressants, anticancer drugs)

Ø       When biodiversity is lost, potential sources of material with significant value to the biosphere and humankind may be lost with it.

Threats to Biodiversity

¨       Human activity can reduce biodiversity by:

¨       altering habitats

¨       hunting species to extinction

¨       introducing toxic compounds into food webs

¨       introducing foreign species to new environments

Ø       As human activities alter ecosystems, this may lead to the extinction of species.

Ø       Extinction occurs when a species disappears from all or part of its range.

Ø       Endangered species is a species whose population size is declining in a way that places it in danger of extinction.

Habitat Alteration

¨       A species’ long-term survival depends on the preservation of the land where the natural habitats exist.

¨       As habitats disappear, the species that live in those habitats vanish.

¨       Habitat fragmentation occurs when development often splits ecosystems into pieces.

¨       The pieces of the habitat become biological “islands”.

¨       A biological island can be any patch of habitat surrounded by a different habitat.

Ø       New York’s Central Park is an island of trees and grass in a sea on concrete.

Ø       In suburbs, patches of forest can be surrounded by farms, houses, and shopping malls.

¨       The smaller the “island”, the fewer species can live there, and the more vulnerable they are to further disturbances.

Demand for Wildlife Products

¨       Humans have pushed some animal species to extinction by hunting them for food or other products.

¨       Today, endangered species are protected from hunting.

¨       Hunting still threatens rare animals in Africa, South America, and Southeast Asia.

¨       Some species are hunted for meat, fur, or hides in addition to body parts such as horns or tusks.

¨       CITIES (Convention on International Trade in Endangered Species) bans international trade in products derived from a list of endangered species.

Pollution

¨       The accumulation of toxic compounds in the tissues of organisms is a serious problem.

¨       DDT is a historical case of a pesticide being passed through the food chain.

¨       DDT has two properties that make it hazardous:

Ø       Nonbiodegradable, which means it, cannot be broken down by metabolic processes.

Ø       When DDT is picked up by organisms, they do not eliminate it from their bodies.

¨       Because it remains stored in an organisms tissues, it has the ability to be passed through the food chain.

¨       Biological magnification is a process where concentrations of a harmful substance increase in organisms at higher trophic levels in a food chain or food web.

¨       DDT caused the eggs of osprey, brown pelican and eagles to have thin shells threatening their survival.

¨       By the early 1970’s, DDT was banned in the U.S. and in most other industrialized countries.

¨       Since the ban, there has been a recovery in the populations of birds that were affected.

Introduced Species

¨       One of the most important threats to biodiversity comes from apparently harmless plants and animals that humans transport around the world.

¨       Introduced into new habitats, these organisms often become invasive species that reproduce rapidly.

¨       Invasive species increase their populations because their new habitat lacks the parasites and predators that control their population.

¨       Invasive species causing ecological problems include:

Ø       Zebra mussels, an aquatic pest which came on ships during the 1980’s

Ø       Cane toads

Ø       The leafy spurge, a European weed which now infests millions of hectares of grasslands across the Northern Great Plains

Conserving Biodiversity

¨       Conservation is used to describe the wise management of natural resources.

¨       The modern science of conservation biology seeks to protect biodiversity.

Strategies for Conservation

¨       Many conservation efforts are aimed at managing individual species to keep them from becoming extinct.

Ø       Zoos have established captive breeding programs

¨       Conservation efforts also focus on protecting entire ecosystems.

¨       This ensures that the natural habitat and many different species are preserved at the same time.

Ø       Governments and conservation groups set aside land such as parks and preserves.

Ø       Marine sanctuaries protect coral reefs and marine mammals.

¨       With this challenge being so large, “hot spots” have been designated as a priority location where significant numbers of habitats and species are in immediate danger.

Conservation Challenges

¨       Protecting resources for the future can require people to change the way they earn their living today.

¨       Conservation efforts attempt to maximize benefits while minimizing economic costs.