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Ecology
Biodiversity and Conservation
Textbook Chapter 5
Review Book Topic 6
What is Biodiversity?
• The variety of life in an given area
• Determined by the number of different species
present
• High biodiversity increases the stability and
health of an ecosystem
• Three types:
– Genetic diversity
– Species diversity
– Ecosystem diversity
• Genetic diversity
– Variety of genes or inheritable characteristics
(within DNA) that are present in a population
– Characteristic examples:
• Color
• Resistance to disease
• Adaptability to the environment
– Within a population, genetic diversity ↑ the
chances of survival during changing
environmental conditions or threats of disease
• Species diversity
– Number of different species and the relative
abundance of each within a community
– Not evenly distributed across the biosphere
• Increases from the polar caps to the equator
• Ecosystem diversity
– Variety of ecosystems within the biosphere
– Remember ~ Ecosystems consist of the
interacting population and the abiotic factors
that support them
– All of the ecosystems on earth support a
diverse collection of organisms
Why is Biodiversity Important?
• Direct economic value
– Humans depend on plants and animals for
food, clothing, energy, medicine, and shelter
– Preserving the organisms we use today is
important to sustain our current way of life
– Humans must also preserve species which
may be useful in the future
– Some organisms we use today are not
very diverse or capable of meeting our
needs
• Closely related counterparts might be a
better source to meet our needs
• Genetic engineering
–Ex. Corn versus teosinte
–Ex. Madagascar periwinkle, penecillian,
and salicin
• Indirect economic value
– Green plants produce oxygen which we
breathe and recycle carbon dioxide
– Natural processes provide us with drinking
water
– Ecological cycles of carbon, phosphorous,
nitrogen, oxygen, etc.
– Decomposers, climate
regulators, fertile soil,
protection against
floods/droughts,
– Nature can provide
services at less expense
than using technology to
provide the same service
in some instances
• Aesthetic (personal/emotional) and
scientific value
Threats to Biodiversity
• Extinction occurs when an entire species
permanently disappears from the
biosphere
– Past causes of extinction
were natural gradual
extinctions where new
species evolved and
biodiversity recovered after millions of years
– The current high rate of extinction is due to a
single species – humans - who are changing
Earths conditions faster than species can
evolve to meet these changes
• 25% – 33% or all plant and animal species will
become extinct within the next 100 years
• Current extinction rates are 1000 more than
normal extinction rates of the past
• Most extinctions will occur near the equator and on
islands
← May 15, 1989
September 1914 →
1937 →
← 1651
Mammal List
• Loss of Natural Resources
– All materials and organisms found in the
biosphere
– Includes minerals, fossil fuels, nuclear fuels,
plants, animals, soil, clean water, clean air
and solar energy
– Species trying to cope with extinction
(including evolving to meet these new
conditions) do not have the natural resources
they need
• Habitat Loss (#1)
– Destruction of habitat
• Has direct impact on biodiversity of the area
• Ex. clearing of land with bulldozers, fire, cutting
down forests
– Disruption of habitat
• Habitat not destroyed but specific populations are
affected
• Disrupts food web and all species in that habitat
• Ex. Over harvesting within “fishing grounds”
• Overexploitation (#2)
– Excessive use of species that have economic
value
– Ex. American bison
• 50 million at one point
• Today, there are less than 1,000 left in the wild
– Ex. Ocelot, rhinoceros, tigers, elephants
• Hunted for pelts and body parts
which are used to produce goods
and medicine
• Fragmentation of
Habitat
– Separation of a
habitat into smaller
pieces of land
– Forces populations to be confined to
small habitats
• Many species will not cross man-made
barriers
• Smaller habitat = smaller populations
• Increases inbreeding and genetic problems
in populations
• Less able to survive in changing
environments or through disease
• Pollution
– Changes the composition of the air, soil and
water
– Some substances that are released into the
environment (man-made or natural) are
considered pollutants
• Pesticides
• Industrial chemicals
• Waste products
– Biological magnification
• Increasing concentration of toxic
substances in organisms as trophic levels
increase in food chains/webs
– Producers – low concentration
– Top consumers – high concentration
– Ex. Pesticide DDT was used on plants to
prevent bugs from eating the leaves but it
almost lead to the extinction of the bald eagle
– Acid precipitation
• Created from the burning of fossil fuels
• Releases sulfur dioxide and nitrogen oxide into the
air
• When these gases react with water, sulfuric acid
and nitric acid are produced
• Enters the water cycle in various forms of
precipitation
– Affects soil, plants and animals
– Eutrophication
• Form of water pollution that destroys underwater
habitats
• Occurs when fertilizers, animal wastes or sewage
flow into waterways
• Causes extreme algae growth which depletes the
oxygen in the water and poisons the water
• Natural process but human activities have
increased the rate at which it occurs
• Invasive Species
– Nonnative species have been introduced to a
habitat intentionally or by accident
– Population controls are not in place in these
new habitats to regulate the effects of the
introduced species
– Out compete, over populate and exploit the
native species within the affect habitat
– Estimated that 40% of extinctions since 1750
have resulted because of invasive species
– Billions of dollars are spent yearly to try to
clean up or control the damage caused by
these species
– Ex. Fire ants, purple loosestrife, zebra
mussels
Conserving Biodiversity
• Natural Resources
– An increase in human population increases
the need and consumption of natural
resources
• Not evenly distributed
– Developed countries have lower populations
but higher consumption rates
– Renewable resources are replaced naturally
at a fast enough rate for continuous
consumption
• Ex. Solar energy, agricultural plants/animals,
water, air
• These resources are NOT unlimited
• If demand is higher than supply, resources can be
depleted
– Nonrenewable resources take extremely long
periods of time to be renewed
• Ex. Coal, minerals, oil, extinct/endangered species
– Sustainable use is an approach where we use
resources at a rate in which they can be
replaced or recycled (preserving biodiversity
and ecosystems)
• Protecting Biodiversity
– Setting up conservation areas worldwide
• Ex. United States national park system
• Ex. 7% of the world is set aside for conservation purposes
– Focus conservation on biodiversity hotspots
– Create corridors between habitat fragments for safe
travel and chances of genetic diversity
• Restoring ecosystems
– Bioremediation is a technique where
organisms are used to detoxify a polluted
area
– Biological augmentation is a technique where
natural predators are added to an ecosystem
to control population sizes of other species
• Legal Protection
– Since the 1970’s, legal action to protect species,
environments and the biosphere has increased
– Ex. United States (1973) ~ Endangered Species Act
– Ex. Worldwide (1975) ~ Convention on International
Trade in Endangered Species of Wild Flora and
Fauna (CITES)