2 Conservation Biology and Biodiversity Conservation biology studies all aspects of biodiversity with the goal of conserving natural resources.A primary goal of conservation biology is the management of biodiversity for sustainable use by humans.Many scientific disciplines come together to achieve this goal.
4 Conservation biology supports these ethical principles: Biodiversity is desirable for all living things.Extinctions, due to human actions, are undesirable.Complex interactions in ecosystems support biodiversity.Biodiversity resulting from evolutionary change has value in and of itself.
5 It is important to understand the: Concept of biodiversity Between 10-20% of living species will go extinct in 20 to 50 years unless immediate steps are taken to protect them.It is important to understand the:Concept of biodiversityValue of biodiversityCauses of present-day extinctionsHow to prevent extinctions from occurring
6 Biodiversity Genetic diversity Community diversity Landscape diversity Biodiversity is the variety of life on earth.There are between 5 to 15 million species in existence.Important aspects of biodiversity are:Genetic diversityCommunity diversityLandscape diversity
7 Number of described species There are only about 1.5 million described species; insects are far more prevalent than organisms in other groups. Undescribed species probably number far more than those species that have been described.
8 Genetic diversity refers to the variations among members of a population. Community diversity is dependent on the interactions of species at a particular location.Landscape diversity involves a group of interacting ecosystems within one landscape.Populations with a high genetic diversity are more likely to have some individuals survive a change in ecosystem structure. Limited genetic variation in crop plant makes them susceptible to being wiped out by a single disease. (Examples: 1846 potato blight in Ireland; 1922 wheat failure in the Soviet Union; 1984 outbreak of citrus canker in Florida.) Loss of genetic diversity increases the likelihood that small, isolated populations will become extinct.Community composition increases the amount of biodiversity in the biosphere, since community composition varies slightly from one location to the next. Saving entire communities, rather than single species, is a better approach to conserving biodiversity.Communities are sometimes connected by small patches within a greater landscape.
9 Distribution of Diversity Biodiversity is not evenly distributed across the biosphere.Biodiversity hotspots contain large concentrations of species but may cover only small portions of the earth.Rain forest canopies and the deep-sea benthos are so diverse they are considered biodiversity frontiers.Conservation efforts are being concentrated on biodiversity hotspots where as many as 20% of the earth’s species exist. The island of Madagascar, the Cape region of South Africa, and the Great Barrier Reef of Australia are all biodiversity hotspots.
10 Value of Biodiversity Biodiversity is a resource of immense value. Direct values include:Medicinal valueAgricultural valueConsumptive use value
11 Medicinal ValueMost of the prescription drugs used in the U.S. were derived from living things.For example, many lives have been saved from cancer with medicine made from the tropical plant, rosy periwinkle.It is likely that an additional 328 types of drugs will be found in tropical rain forests, with a value to society of $147 billion.
12 Agricultural ValueCertain wild plants serve as a source of genetic variation for related crop species.Biodiversity can also provide biological pest controls that reduce the need for chemical pesticides.Wild bees are resistant to mites that have wiped out the honeybee population that pollinates many important crops.
13 Consumptive Use ValueMuch of the freshwater and marine harvest of organisms used for food depends on natural ecosystems rather than aquaculture.Wild fruits and vegetables, fibers, beeswax, and seaweed are important economically.Wood, rubber, and latex are tree products of great economic importance.Sustained production, rather than ecosystem destruction, will ensure that these products are available indefinitely.
14 Indirect Value of Biodiversity Indirect value of biodiversity includes:Biogeochemical cyclesWaste disposalProvision of fresh waterPrevention of soil erosionRegulation of climateEcotourismWe are dependent on biogeochemical cycles to remove excess amounts of nutrients and to provide fresh water. When humans upset these natural cycles, dire environmental consequences, such as pollution, result.Biological communities can break down and immobilize pollutants (i.e., heavy metals and pesticides) that humans release into the environment, thus purifying water.The water cycle continually provides fresh water for use by nonmarine organisms. There is no substitute for fresh water. Forests and other ecosystems exert a “sponge effect”, soaking up water and releasing it at a regular rate. The water-holding capacity of forests decreases the likelihood of flooding, and allows forests to release water slowly over a period of weeks, thus moderating the effects of drought.Intact ecosystems naturally retain soil and prevent soil erosion. Deforestation causes severe soil erosion, ruining river and coastal ecosystems.Locally, trees provide shade and reduce the need for fans and air conditioning. Globally, forests take up carbon dioxide and ameliorate the effects of global warming.Finally, many tourists want to vacation in areas of natural beauty where they can fish or hunt, whale or watch, and hike.
15 Biodiversity and Natural Ecosystems Scientific studies have shown that ecosystem performance improves with increasing species richness.Rates of photosynthesis also increases as diversity increases.It remains to be determined whether more diverse ecosystems are better able to withstand environmental change.
16 Number of plant species and rate of photosynthesis
17 Causes of Extinction Causes of extinction include: Habitat loss Alien speciesPollutionOverexploitationMost threatened and endangered species are imperiled for more than one reason.
18 Habitat Loss Habitat loss has occurred in all ecosystems. Habitat loss in tropical rain forests and coral reefs is of great concern because of the great diversity of species living in these ecosystems.Loss of habitat also affects freshwater and marine biodiversity.The events in Brazil offers a typical example of how rain forest is concerted to land uninhabitable by wildlife. The construction of a major highway provided a route to the interior of the forest. Housing and industry sprang up along the highway, along with additional access roads. The result was fragmentation of the once immense forest. The government offered payments to those who would live in the forest, so people came and cut and burned trees in patches. Tropical soils contain limited nutrients, so soil nutrients support forage for cattle for only about 3 years. Once the land was degraded, the farmer would move his family to the next location and repeat the pattern of habitat loss.Coastal degradation is due to the concentration of people living along the coasts. Approximately 60% of coral reefs have been destroyed or are on the verge of destruction. Mangrove acreage has been reduced by 45%. Wetlands, estuaries, and seagrass beds are being rapidly destroyed.
19 Habitat lossHabitat loss. In a study examining records of imperiled U.S. plants and animals, habitat loss emerged as the greatest threat to wildlife. Macaws that reside in South American tropical rain forests are endangered for the reasons listed in the graph.
20 Road construction in Brazil The construction of roads in an area in Brazil opened up the rain forest and subjected it to fragmentation. The result was patches of forest and degraded land. Wildlife could not live in destroyed portions of the forest.
21 Human colonization of new areas Horticulture and agriculture Alien SpeciesAlien species (exotics) are nonnative species that migrate into new ecosystems or are introduced there by humans.Introduction of alien species by humans has been due to:Human colonization of new areasHorticulture and agricultureAccidental transportAlien species disrupt food webs.When Europeans came to North America, they brought with them familiar species, such as the dandelion that was used as a salad green.Kudzu, a vine from Japan used in the U.S. to reduce soil erosion, now covers much landscape in the South, including walnut, magnolia, and sweet gum trees.Global trade and travel accidentally bring many new species from one country to another. Ballast water released from large ships contains many alien species.
22 Brown tree snake in Guam Black rats in the Galapagos Islands Exotics on IslandsBecause islands have unique assemblages of native species that are closely adapted to one another, introduction of exotic species is especially disruptive.Examples:Myrtle trees in HawaiiBrown tree snake in GuamBlack rats in the Galapagos IslandsMyrtle trees, introduced to Hawaii from the Canary Islands, have symbiotic nitrogen-fixing bacteria that allow this tree to establish itself on nutrient-poor volcanic soils. Once established, myrtle trees halt the normal succession of native plants on volcanic soil.The brown tree snake has been introduced into a number of Pacific Islands, including Guam. On Guam, the snake has reduced 10 native bird species to near extinction.On the Galapagos Islands, black rats have reduced populations of giant tortoise, while goats and feral pigs have destroyed stands of cactus and changed the vegetation from highland forest to pampaslike grassland.
23 Alien speciesMongooses were introduced into Hawaii to control rats, but they also prey on native birds.
24 PollutionPollution is any environmental change that adversely affects the lives and health of living things.Categories include:Acid depositionEutrophicationOzone depletionOrganic chemicalsGlobal warmingSulfur dioxide from power plants and nitrogen oxides from vehicle exhaust are converted to acids when the combine with atmospheric water vapor. These acids return to earth as wet deposition (rain or snow) or dry deposition (sulfate and nitrate salts). Acid deposition weakens trees and increases their susceptibility to disease and insects. It also kills small vertebrates and decomposers, threatening entire ecosystems. Many lakes in the northern United States are now devoid of life because of acid deposition.Eutrophication, or over-enrichment, also stresses lakes. Excess nutrients from agricultural runoff or sewage from wastewater treatment cause algae to grow in abundance. Dying algal blooms use up lake oxygen and can lead to fish kills.The stratospheric layer of ozone shields the earth from harmful ultraviolet (UV) radiation. Release of chlorofluorocarbons from old refrigerators or air conditioners has caused ozone depletion. Severe ozone shield depletion can impair crop production and tree growth, kill plankton, and weaken human immune systems.Organic chemicals used for many applications from pesticides and dishwashing detergents mimic the effects of hormones in ways harmful to wildlife.Global warming refers to an expected increase in average temperature during the twenty-first century. Carbon dioxide, produced primarily from burning fossil fuels, and methane from animals, rice paddies, and petroleum wells, are known as greenhouse gases. Data collected from around the world show a steady increase in the concentrations of greenhouse gases. As oceans warm, temperatures in polar regions will rise to a greater degree than in other areas. The sea level will rise and glaciers will melt. Much of U.S. coastal areas could be inundated. Glibal warming could cause many extinctions on land as well. Present assemblages of species in ecosystems will migrate northward. Trees will be unlikely to migrate rapidly enough to survive.
25 Global warmingMean global temperature change is expected to rise due to the introduction of greenhouse gases into the atmosphere. Global warming has the potential to significantly affect the world’s biodiversity. A temperature rise of only a few degrees causes coral reefs to “bleach” and become lifeless.
26 Colorful parakeets and macaws OverexploitationOverexploitation occurs when too many individuals are taken and population size is severely reduced.Overexploitation occurs in:Decorative plantsExotic aquarium fishColorful parakeets and macawsOceanic fishing areasLegal and illegal harvest of decorative plants (like saguaro cactus) and exotic pets (parakeets, macaws, and tropical fish) has resulted in overexploitation of many populations. Many individual animals die in the process of collecting these species for sale.Declining species of mammals, such as the Siberian tiger, are still hunted for their hides, tusks, horns, or bones. A single Siberian tiger can bring $500,000 because of its rarity. Horns of rhinoceroses and ivory from elephant tusks are in similar demand.The U.N. Food and Agricultural organization indicates that we have now overexploited 11 of 15 major oceanic fishing areas. Huge trawling nets are dragged along the seafloor to capture bottom-dwelling fish, but only the largest fish are kept. The rest are left to die.Overfishing can set in motion a chain of events that detrimentally alters the food web of a ecosystem.
27 TrawlingThese Alaskan pollock were caught by dragging a net along the seafloor. These photos show the appearance of the seabed before and after the net went by.
28 Conservation Techniques To preserve species, it is necessary to preserve their habitat.Preserving biodiversity hotspots will help save greater numbers of species.The preservation of a keystone species can preserve biodiversity in a habitat.Saving metapopulations, including the source population and sink population, is important in species preservation.Biodiversity hotspots are relatively small areas having a concentration of endemic (native) species not found elsewhere. In the tropical rain forests of Madagascar, 93% of the primate species, 99% of the frog species, and over 80% of the plant species are endemic to Madagascar. Preserving these forests will preserve a wide variety of organisms.Keystone species are those that influence the viability of a community more trhan you would expect from their numbers. The extinction of a keystone species can lead to other extinctions and a loss of biodiversity. For example, bats are a keystone species in tropical forests of the Old World. They are pollinators that also disperse the seeds of trees. Without the bats, the trees fail to reproduce. The grizzly bear is a keystone species in the northwestern U.S. and Canada. Bears disperse berries and their seeds, kill the young of many hoofed animals thus keeping prey populations sizes in check, and they also are a primary mover of soil.A metapopulation is one that is subdivided into several small, isolated populations due to habitat fragmentation. The grizzly bear population makes up a metapopulation. A source population is the one that likely lives in a favorable area with a birthrate higher than its death rate. Individuals from source populations move into sink populations where the environment is not as favorable and death rate equals birth rate at best.
29 Habitat preservationWhen particular species are protected, other wildlife benefits. The Greater Yellowstone Ecosystem has been delineated in an effort to save grizzly bears, which need a very large habitat. Currently the remaining portions of old-groth forests in the Pacific Northwest are not being logged in order to save the northern spotted owl.
30 Landscape DynamicsA landscape encompasses different types of ecosystems.Landscape protection for one species often benefits other wildlife sharing the same space.When preserving landscapes, the edge effect must be considered because it can have a serious impact on population size.The edge effect: An edge reduces the amount of habitat typical of an ecosystem because the edges around a patch have a habitat slightly different from the interior of a patch.
31 Edge effectThe smaller the patch, the greater the proportion that is subject to the edge effect.
32 Computer AnalysesGap analysis uses the computer to find gaps in preservation, places where biodiversity is high outside of preserved areas.A population viability analysis helps researchers determine the amount of habitat a species requires to maintain itself.
33 Habitat RestorationRestoration ecology is a subdiscipline of conservation biology that seeks scientific ways to return ecosystems to their former state.A restoration plan has been developed for the Everglades that will sustain the Everglades ecosystem while maintaining flood control.
34 Restoration of the Everglades If the Everglades are restored, the chances for survival for these wild animals will improve.
35 Three principles of restoration ecology have emerged: It is best to begin as soon as possible before remaining fragments of habitat are lost.It is best to use biological techniques that mimic natural processes to bring about restoration.The goal is sustainable development, the ability of the ecosystem to maintain itself while serving human beings.
36 Chapter SummaryConservation biology is the scientific study of biodiversity and its management for sustainability.Biodiversity must be preserved as genetic, community, and landscape diversity.Biodiversity has direct and indirect values.
37 Researchers have identified the major causes of extinction, including habitat loss, alien species introduction, pollution, and overexploitation.To preserve species, habitat must be preserved.Sometimes habitat must be restored before sustainable development is possible.