Biology 2014-2015

Sec. 6-3 Biodiversity
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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.

       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)

       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

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

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

       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.

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

       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:

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

       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:

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

       Cane toads

       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.

       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.

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

       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.