copyright © 2005 pearson education, inc. publishing as benjamin cummings species diversity the...

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Species Diversity

• The species diversity of a community

– Is the variety of different kinds of organisms that make up the community

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• Species richness

– Is the total number of different species in the community

• Relative abundance (evenness)

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• Two different communities

– Can have the same species richness, but a different relative abundance


Simpson diversity index

• Can be used to measure and compare the species diversity of a community/ecosystem

• Is a measure that takes into account both richness and evenness

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• Biogeographic factors affect community diversity

• Two key factors correlated with a community’s species diversity

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• Species richness generally declines along an equatorial-polar gradient (moving latitudinally from equator towards the poles)

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• Climate

– Is likely the primary cause of the latitudinal gradient in biodiversity


• The two main climatic factors correlated with biodiversity

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Area Effects

– All other factors being equal, the larger the geographic area of a community, the greater the number of species


• A species-area curve of North American breeding birds

– Supports this idea


Island Equilibrium Model

• Species richness on islands

– Depends on island size, distance from the mainland, immigration, and extinction


• Studies of species richness on the Galápagos Islands

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Reasons for conservation of biodiversity

• Aesthetics - ensure that future generations can experience the beauty of ecosystems such as rainforests

• Potential source of new biopharmaceuticals, medicines, genes for genetic engineering, phytochemicals

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• Economic reasons

– Farming on clear-cut rainforests has not been successful

– Potential sources of chemicals, genes used to improve crops

• Ecological reasons

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– Protect against invading organisms (competition)

– More CO2 in atmosphere leading to global warming

– Soil erosion, flooding



• Ethical reasons

– Affects local populations most

– Ensure future generations can enjoy

• Aesthetics


Arguments against conservation

• May slow down economic development of some countries


Introduction of alien species

• Disrupts communities

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• Many nonnative species provide us with food, medicine, and other benefits but a few can wipe out native species, disrupt ecosystems, and cause large economic losses.


INVASIVE SPECIES

• Kudzu:deliberate release of an alien species

Kudzu vine was introduced in Kudzu vine was introduced in the southeastern U.S. to the southeastern U.S. to control erosion. It has taken control erosion. It has taken over native species habitats.over native species habitats.


Zebra mussels:accidental release of an alien species

• May have been introduced by European cargo ships which contained mussels in ballast water

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Prickly pear: an alien species under control

• Introduced to Australia in mid 1800’s

• Spread rapidly

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• Moth quickly destroyed prickly pear, and exists in a balance today - an example of biological control


Impact of alien species on ecosystems

• Interspecific competition - may out-compete native species, resulting in a loss in biodiversity

– Red squirrel/grey squirrel

• Predation - may feed on other species

– Lampreys

• Species extinction - out-compete native species leading to their extinction

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INVASIVE SPECIES

• Many invasive species have been introduced intentionally.


INVASIVE SPECIES

• Many invasive species have been introduced unintentionally.


INVASIVE SPECIES

• The Argentina fire ant was introduced to Mobile, Alabama in 1932 from South America.

– Most probably from ships.

– No natural predators.


INVASIVE SPECIES

• Prevention is the best way to reduce threats from invasive species, because once they arrive it is almost impossible to slow their spread.


Biological control

• Using a natural predator to control an unwanted or invasive species

• Carries great risk of unexpected consequences

• Gallerucella beetles have been released to attempt to control Purple Loosestrife

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Biomagnification

• Process by which chemical substances become more concentrated at each trophic level

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• DDT caused eggs of predatory birds to have thin shells which cracked when mother birds sat on them - caused a decline in number of predator birds


Pollution

• Each year pesticides:

– Kill about 1/5th of the U.S. honeybee colonies.

– 67 million birds.

– 6 -14 million fish.

– Threaten 1/5th of the U.S.’s endangered and threatened species.

Example of biomagnification Example of biomagnification of DDT in an aquatic food of DDT in an aquatic food chain.chain.


Effects of ultraviolet radiation

• Non-lethal skin cancer

• Lethal skin cancers

• DNA mutations

• Sunburn

• Cataracts

• Reduced biological productivity


OZONE DEPLETION IN THE STRATOSPHERE

• Less ozone in the stratosphere allows for more harmful UV radiation to reach the earth’s surface.

– The ozone layer keeps about 95% of the sun’s harmful UV radiation from reaching the earth’s surface.

– Chlorofluorocarbon (CFCs) have lowered the average concentrations of ozone in the stratosphere.

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Depletion of Atmospheric Ozone

• Life on Earth is protected from the damaging effects of UV radiation

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• Satellite studies of the atmosphere

– Suggest that the ozone layer has been gradually thinning since 1975


• The destruction of atmospheric ozone

– Probably results from chlorine-releasing pollutants produced by human activity


• Scientists first described an “ozone hole”

– Over Antarctica in 1985; it has increased in size as ozone depletion has increased


OZONE DEPLETION IN THE STRATOSPHERE

• Ozone thinning: caused by CFCs and other ozone depleting chemicals (ODCs).

– Increased UV radiation reaching the earth’s surface from ozone depletion in the stratosphere is harmful to human health, crops, forests, animals, and materials such as plastic and paints.


• The average area covered by the Antarctic ozone hole this year (2012) was the second smallest in the last 20 years, according to data from NASA and National Oceanic and Atmospheric Administration (NOAA) satellites.

The average size of the 2012 ozone hole was 6.9 million square miles. The Sept. 6, 2000 ozone hole was the largest on record at 11.5 million square miles


Conservation of Biodiversity

• Indicator species are those that are very sensitive to environmental change

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• Lichens are a common indicator species because they are very sensitive to pollution, they can also show the presence of metals such as lead and mercury in the air

• Macroinvertebrates (insect larvae) are an indicator species that can be used to determine the quality of water

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• Very sensitive organisms like mayfly and caddisfly larvae require high levels of oxygen and low levels of organic matter


Biotic index

• As measurement that determines the quality of water in an environment

• Measures the number of different types of organisms in each group multiplied by a sensitivity factor

– Sensitive X 3

– Somewhat sensitive X 2

– Tolerant X 1

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The Passenger Pigeon - Gone Forever

• Once the most numerous bird on earth.

• In 1858, Passenger Pigeon hunting became a big business.

• By 1900 they became extinct from over-harvest and habitat loss.


• The Passenger Pigeon, once probably the most numerous bird on the planet. Their flocks, a mile wide and up to 300 miles long, were so dense that they darkened the sky for hours and days as the flock passed overhead. Total populations may have reached 5 billion individuals and comprised up to 40% of the total number of birds in North America.


Carolina parakeet

• Became extinct in wild around 1900

• Settlers cleared trees destroying habitat

• Release of honeybees displaced parakeets from nesting in trees

• Hunted for feathers which were used to make women’s hats


SPECIES EXTINCTION

• Species can become extinct:

– Locally: A species is no longer found in an area it once inhabited but is still found elsewhere in the world.

– Ecologically: Occurs when so few members of a species are left they no longer play its ecological role.

– Globally (biologically): Species is no longer found on the earth.


Global Extinction

• Some animals have become prematurely extinct because of human activities.


Endangered and Threatened Species

• Endangered species: so few individual survivors that it could soon become extinct.

• Threatened species: still abundant in its natural range but is likely to become endangered in the near future.


• Some species have characteristics that make them vulnerable to ecological and biological extinction.

SPECIES EXTINCTION


SPECIES EXTINCTION

• Scientists use measurements and models to estimate extinction rates.

– The International Union for the Conservation of Nature and Natural Resources (IUCN) publishes an annual Red List, listing the world’s threatened species.

– The 2004 Red List contains 15,589 species at risk for extinction.


SPECIES EXTINCTION

• Percentage of various species types threatened with premature extinction from human activities.


IMPORTANCE OF WILD SPECIES

• We should not cause the premature extinction of species because of the economic and ecological services they provide.

• Some believe that each wild species has an inherent right to exist.

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HABITAT LOSS, DEGRADATION, AND FRAGMENTATION

• Conservation biologists summarize the most important causes of premature extinction as “HIPPO”:

– Habitat destruction, degradation, and fragmentation

– Invasive species

– Population growth

– Pollution

– Overharvest


OVEREXPLOITATION

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• Killing predators and pests that bother us or cause economic losses threatens some species with premature extinction.

• Legal and illegal trade in wildlife species used as pets or for decorative purposes threatens some species with extinction.


OVEREXPLOITATION

• Rhinoceros are often killed for their horns and sold illegally on the black market for decorative and medicinal purposes.


•In TCM the bones of tigers have been used in manufactured medicines to treat arthritis and other joint ailments.

•Rhinoceros horn is used in TCM to treat fever, convulsions, and delirium.

•Bear bile is used in TCM to treat a wide variety of illnesses and injuries, including liver ailments and headaches.

•Musk from the musk deer is the basis of some 300 TCM prescriptions, of various remedies in Western homeopathic medicine, and of some perfumes. It is used to promote circulation and to treat skin infections and abdominal pain

•The seahorse, used as a treatment for kidney ailments, circulatory problems, and impotence.

•Alligator meat is promoted as a way to cure the common cold and to prevent cancer, and alligator organs are also said to have medicinal properties.

Asian elephants are killed for their meat, hide, tusks and other body parts. In Myanmar, for example, small pieces of elephant foot are turned into a paste to treat hernias.

The sun bear is just one of several bear species killed for its gallbladder, which is used for treating everything from burns to asthma to cancer.

Zebra’s meat and fat are used to treat diseases such as tuberculosis.


Case Study:Rising Demand for Bushmeat in Africa

• Bushmeat hunting has caused the local extinction of many animals in West Africa.

• Can spread disease such as HIV/AIDS and ebola virus.


PROTECTING WILD SPECIES: LEGAL AND ECONOMIC APPROACHES

• International treaties have helped reduce the international trade of endangered and threatened species, but enforcement is difficult.

– One of the most powerful is the 1975 Convention on International Trade of Endangered Species (CITES).

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Case Study: The U.S. Endangered Species Act

• One of the world’s most far-reaching and controversial environmental laws is the 1973 U.S. Endangered Species Act (ESA).

– ESA forbids federal agencies (besides defense department) to carry out / fund projects that would jeopardize an endangered species.

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Case Study: The U.S. Endangered Species Act

• Biodiversity hotspots in relation to the largest concentrations of rare and potentially endangered species in the U.S.


Endangered Species

• Because of scarcity of inspectors, probably no more than 1/10th of the illegal wildlife trade in the U.S. is discovered.


Endangered Species

• Congress has amended the ESA to help landowners protect species on their land.

• Some believe that the ESA should be weakened or repealed while others believe it should be strengthened and modified to focus on protecting ecosystems.

• Many scientists believe that we should focus on protecting and sustaining biodiversity and ecosystem function as the best way to protect species.


PROTECTING WILD SPECIES: THE SANCTUARY APPROACH

• The U.S. has set aside 544 federal refuges for wildlife, but many refuges are suffering from environmental degradation.

Pelican Island was the Pelican Island was the nation’s first wildlife refuge.nation’s first wildlife refuge.


PROTECTING WILD SPECIES: THE SANCTUARY APPROACH

• Gene banks, botanical gardens and using farms to raise threatened species can help prevent extinction, but these options lack funding and storage space.

• Zoos and aquariums can help protect endangered animal species by preserving some individuals with the long-term goal of reintroduction, but suffer from lack of space and money.


Features of nature reserves which promote biodiversity

• Size of the reserve

– Larger reserves sustain larger populations which are safer from extinction from unexpected factors like fire, also have less edge area

• Edge effect

– Edge between ecosystem and disturbed habitat and center of ecosystem differ

– Organisms at edge of ecosystem suffer from more predation and competition from invasive species

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• Corridors

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– Corridors may expose animals to predation, allow invasive species to enter and may negatively impact human activity


Management of conservation areas

• Restoration - return land to natural state

• Recovery of threatened species -restoration and protection of habitat for endangered species

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• Legal protection against development or pollution

• Funding and prioritizing


In situ conservation methods

• Keeping organisms “in situ” or in place in situation where they belong

• Organisms adapted to the conditions they live in, nature reserves protect endangered species by maintaining habitat and prevent competition by removing invasive species

• Defend against predators, poaching

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Ex situ conservation methods

• Used as a last resort when natural habitat is not safe or population is too small to sustain itself

– Captive breeding in zoos

– Botanical gardens

– Seed banks


Black-footed ferret

• In 1987 last of wild ferrets captured

• Numbered 18

• Through captive-breeding programs, 2008 estimates put population at 750 in the wild and 250 captive animals


California condor

• 1982 - 22 birds remaining in wild

• 1987 last bird captured from wild

• 2000 - 157 condors/62 released into wild




• Do not buy furs, ivory products, and other materials made from endangered or threatened animal species.

• Do not buy wood and paper products produced by cutting remaining old-growth forests in the tropics.

• Do not buy birds, snakes, turtles, tropical fish, and other animals that are taken from the wild.

• Do not buy orchids, cacti, and other plants that are taken from the wild.

• Spread the word. Talk to your friends and relatives about this problem and what they can do about it.

What Can You Do?

Protecting Species

copyright © 2005 pearson education, inc. publishing as benjamin cummings species diversity the...

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