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Biodiversity
Biodiversity
• Biological diversity or “Biodiversity” = the sum total of the
genetically based variety of all organisms in the biosphere
• Our existence relies on a great variety of other organisms.
• Some branches within biodiversity:
– Ecosystem diversity = variety of habitats,
communities, and ecological processes in the
ecosystem
– Species diversity = number of different species in
the system
– Genetic diversity = sum total of all the different
forms of genetic information carried by all
organisms present
Species Diversity
Section 6-3
Insects
54.4%
Protists
4.2%
Other Animals
19.7%
Plants
18%
Fungi
3.4%
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Section:
Bacteria
0.3%
Value of Biodiversity
• Biodiversity is one of Earth’s greatest natural
resources providing us with food, industrial
products, and medicines (painkillers, antibiotics,
heart drugs, antidepressants, and anticancer
drugs)
• When biodiversity is lost, potential sources of
material with significant value to the biosphere
and to humankind may be lost.
• Think of biodiversity as a library- lost species are
essentially lost books that can’t be replaced.
Threats to Biodiversity
 Human activities can reduce biodiversity by:
 Habitat alteration
 Hunting species to extinction
 Extinction = occurs when a species disappears from all or
part of its range
 Endangered species = species in danger of extinction with
declining population sizes
 As the population declines, the species loses genetic
diversity, making it more vulnerable to extinction
 Introducing toxic compounds (pollutants) into food
webs
 Introducing foreign species to new environments
Habitat Alteration & Fragmentation
• When land is developed, natural habitats may
be destroyed and the species that live in those
habitats may vanish
• Habitat fragmentation = development of land
that splits ecosystems into pieces resulting in
biological “islands” with fewer species and
smaller populations more vulnerable to
further disturbances or climate changes
– Reduces habitat space
– Restricts movement
– Reduces diversity
Fragmentation
Hunting/Wildlife Products
• In the past, hunting for meat, fur, hides or other body
parts caused the extinction of some species
• Today, endangered species are protected from hunting by
laws in most of the world
• Endangered Species- species in danger of going extinct.
Protected by international and local laws
– Poaching is still a major problem
• Bear gall bladders, ivory, shark fins, tiger bones, etc.
Pollution
• Pollution can threaten biodiversity, because toxic
compounds accumulate in tissue of organisms
– Toxic wastes, sedimentation, thermal pollution
• Biological magnification = increasing
concentrations of harmful substances in
organisms at higher trophic levels in a food
chain/web
– Entire food web is affected, but top-level carnivores
are at highest risk
Biological Magnification of DDT
Section 6-3
Magnification of
DDT Concentration
Fish-Eating Birds
10,000,000
Large
Fish
Small Fish
100,000
Zooplankton
10,000
Producers
Water
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Section:
1,000,000
1000
1
Thermal Pollution
• Thermal pollution: is the degradation of water
quality by any process that changes ambient water
temperature
– Power plants and industry using local water supplies to
cool during manufacturing.
– The temperature of the discharge water is significantly
warmer than normal
– Warmer water holds less
Oxygen, supports less life
Introducing Foreign Species
 Biodiversity is also threatened by apparently
harmless plants and animals that humans transport
around the world either accidentally or intentionally
 Invasive species = organisms introduced into new
habitats and reproduce rapidly (think exponential)
lacking the parasites and predators that control
population size in their native country
 They can displace native species driving them close
to extinction
 Ex. Zebra Mussels
Invasive species
 Non-native species
 reduce diversity in ecosystem
 examples





African honeybee (killer bees)
gypsy moth
zebra mussel
purple loosestrife
Phragmites
phragmites
gypsy moth
kudzu
Purple loosestrife
1968
1978


reduces diversity
loss of food & nesting sites for
animals
Zebra mussel
~2 months


ecological & economic damage

reduces diversity
loss of food & nesting sites for
animals
economic damage
Brown Tree Snakes, Guam
• This introduced snake has caused the extinction
on Guam of 12 of 14 forest bird species, two of
three bat species, and at least six lizard species.
– Grow up to 8-10 feet long.
– Hatch at 15 inches can grow to 3 feet in one year
Guam Bird Populations
Conserving Biodiversity
• Conservation = wise management of natural resources
– Preservation of habitats and wildlife to protect
Earth’s biodiversity for future generations,
however protected areas may not be enough
• Current conservation efforts focus on protecting individual
species as well as entire ecosystems (to ensure natural
habitats and interactions among different species are
preserved).
• “Hot spots” = places around the world where everything
possible is being done to conserve the ecosystem and species
World Wide Hotspots