The Value of Biodiversity
¨ Biodiversity is the sum total of the genetically based variety of all organisms in the biosphere.
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:
¨ Industrial products
¨ Medicines (painkillers, antibiotics, heart drugs, antidepressants,
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
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
¨ 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
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
¨ 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.
¨ 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
¨ DDT has two properties that make it hazardous:
Ø Nonbiodegradable, which means it, cannot be broken down by metabolic
Ø When DDT is picked up by organisms, they do not eliminate it from
¨ 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.
¨ 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
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
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.
¨ 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.