ecology biodiversity and conservation textbook chapter 5 review book topic 6
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EcologyBiodiversity 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
← 1651
1937 →
September 1914 →
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 goodsand 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)
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