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BIOLOGY CONCEPTS & CONNECTIONS Fourth Edition Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor CHAPTER 38 Conservation Biology Modules 38.1 – 38.3 From PowerPoint® Lectures for Biology: Concepts & Connections Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Saving the Key Deer • Modern human culture and the rapidly growing global human population have created a biodiversity crisis – There is a rapid decrease in the variety of species on Earth • The decline in Key deer populations is an example of this crisis – The Key deer is a miniature subspecies of the whitetail deer found only in the Florida Keys Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The Key deer was nearly exterminated by hunting in the early 1900s • The National Key Deer Pine Refuge was established on Big Pine Key island in 1957 – The deer population rebounded to 600-800 • The Key deer is still on the endangered species list Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The human population on Big Pine Key has increased tenfold since 1967 – Development has reduced the Key deer habitat – Motorists have become the main threat to the deer's survival Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Conservation biology is a goal-oriented science that seeks to counter the biodiversity crisis • Conservation biology relies on research from all levels of ecology, from populations to ecosystems Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings THE BIODIVERSITY CRISIS: AN OVERVIEW 38.1 Habitat destruction, introduced species, and overexploitation are the major threats to biodiversity • Human alteration of habitats poses the single greatest threat to biodiversity – The loss of tropical rain forests and marine habitats are especially devastating Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 38.1A • Competition with introduced species also threatens many species in their native habitats – Introduced species are those that have been transferred to an area where they did not occur naturally – Examples: European starlings, pigeons, and house sparrows Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • One of the largest rapid-extinction events ever recorded occurred in Lake Victoria, East Africa – 200 species of freshwater fish were lost due to the introduction of the Nile perch Figure 38.1B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Overexploitation of wildlife also threatens many species – Excessive commercial harvest or sport hunting has reduced the numbers of many species – Examples: whales, American bison, Galápagos tortoises, and numerous fish Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 38.2 Biodiversity is vital to human welfare • Preservation of biodiversity is important to humans for aesthetic, ethical and practical reasons • Biodiversity provides humans with food, clothing, shelter, oxygen, soil fertility, etc. • We evolved in Earth's ecosystem – Large-scale changes in the ecosystem threaten us as well as other species Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Medicinal plants and their derivatives play an important role in the pharmaceutical industry – The rosy periwinkle of Madagascar provides two substances effective in the treatment of Hodgkin’s disease Figure 38.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 38.3 Connection: Technology and the population explosion compound our impact on habitats and other species • The explosive growth of the human population and of technology continues today • Although the populations of developing nations are growing the fastest, it is the resource consumption of the less populous, developed nations that puts a greater strain on the biosphere Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Table 38.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Oil spills, acid rain, ozone depletion, and chemical pesticides affect the entire world Figure 38.3a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Chemical pesticides are concentrated in food chains by biological magnification DDT concentration: increase of 10 million times DDT in fish-eating birds 25 ppm DDT in large fish 2 ppm DDT in small fish 0.5 ppm DDT in zooplankton 0.04 ppm DDT in water 0.000003 ppm Figure 38.3B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 38.4 Connection: Rapid global warming could alter the entire biosphere • Burning of fossil fuels is increasing the amount of CO2 and other greenhouse gases in the air Figure 38.4A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Light CO2 Heat CO2 CO2 Figure 38.4B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Projected atmospheric temperatures indicate an increase in greenhouse gases Figure 38.4C Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • An increase in global temperature could have many negative effects – Change in climate patterns – Melting of polar ice – Flooding of coastal regions – Increase in the rate of species loss Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings THE GEOGRAPHIC DISTRIBUTION OF BIODIVERSITY 38.5 Some locations in the biosphere are especially rich in biodiversity • Environments are patchy – As a result, species are not evenly distributed • Geographic distribution patterns for many species indicate an uneven density – Example: terrestrial birds in North and Central America Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Density of bird species Figure 38.5A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Biodiversity hot spots are relatively small areas with a large concentration of species • Many species in these hot spots are endemic – They are found nowhere else • Biodiversity hot spots can also be hot spots of extinction Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Location of some biodiversity hot spots Figure 38.5B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Endemic species are highly sensitive to habitat degradation and thus prone to extinction • Many migratory species, both terrestrial and aquatic, require international protection Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Monarch butterflies migrate throughout Canada and the United States during the summer months – In the autumn months, they migrate to local sites in Mexico and California – Such overwintering populations are susceptible to habitat disturbances Figure 38.5C Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Sea turtles, such as the loggerhead turtle, are threatened in their ocean feeding grounds and on land Figure 38.5D Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings CONSERVATION OF POPULATIONS AND SPECIES 38.6 There are two approaches to studying endangered populations • Habitat degradation can lead to population fragmentation – Portions of populations are split and subsequently isolated – It often results in species being designated as threatened or endangered Figure 38.6A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The Endangered Species Act (ESA) defines an endangered species as one that is in danger of extinction throughout all or a significant portion of its range – Example: the northern spotted owl • The ESA defines a threatened species as one that is likely to become endangered in the foreseeable future Figure 38.6B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Some conservation biologists believe that the smallness of a population will ultimately drive it to extinction • The small-population approach – Identifies the minimum viable population size for a threatened species – Focuses on preserving genetic variation • The declining-population approach diagnoses and treats the causes of a population's decline Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 38.7 Identifying critical habitat factors is a central goal in conservation research • Identifying the specific combination of habitat factors that is critical for a species is pivotal in conservation biology • The red-cockaded woodpecker requires three habitat factors – A mature pine forest Figure 38.7A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings – Low growth of plants among the mature pine trees – Controlled fires to reduce forest undergrowth Figure 38.7B, C Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 38.8 Connection: Increased fragmentation threatens many populations: A case study • Increased fragmentation threatens many species – This includes those whose populations were historically highly fragmented Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • One example is the endangered bull trout – It inhabits lakes, rivers, and mountain streams in northwestern Canada and the United States Figure 38.8A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The bull trout requires cold, fast-flowing streams with pebble-covered bottoms and little or no silt Figure 38.8B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Before human intervention, the bull trout population consisted of four subpopulations S1 S3 S2 S4 Egg-laying sites in mountain streams Regular, frequent dispersal and gene flow between subpopulations Irregular, infrequent dispersal; minimal gene flow between subpopulations Figure 38.8C, left Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The bull trout population has been further fragmented and reduced by – the construction of hydroelectric dams – logging – road building – mining s1 s2 Mill site for silver mine s3 s5 s4 Hydroelectric dam Hydroelectric dam Egg-laying sites in mountain streams Clear-cut (logged) areas Roads Irregular, infrequent dispersal; minimal gene flow between subpopulations Figure 38.8C, right Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Conservation biologists often use computer simulations in a population viability analysis (PVA) – PVA incorporates as much information about a population's current status as available – It predicts a species' chance for long-term survival Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings MANAGING AND SUSTAINING ECOSYSTEMS 38.9 Sustaining ecosystems and landscapes is a conservation priority • Conservation efforts are increasingly aimed at learning how to sustain whole ecosystems and landscapes • Landscape ecology employs ecological principles to study land-use patterns – It aims to make species conservation a functional part of those patterns Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Researchers often use gap analysis to study the distribution of organisms relative to landscape features and habitat types • Gap analysis employs computerized maps along with information on the distribution of organisms Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Map of vegetation patterns and river course Distribution of rare, endemic species Distribution of protected areas Final overlay map Figure 38.9A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Gap analysis can highlight areas with the greatest concentrations of rare and endangered species outside of protected areas – It can lead to sustaining the biodiversity of the whole area Figure 38.9B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 38.10 Edges and corridors can strongly influence landscape biodiversity • Boundaries between ecosystems have their own set of features and assemblages of species • Human activities can create edges that are more abrupt than those found naturally Figure 38.10A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The increased frequency and abruptness of edges can increase the loss of species – Populations of the brown-headed cowbird, an edge-adapted species, are currently expanding – Populations of songbird species are declining Figure 38.10B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Movement corridors are strips or clumps of quality habitat that connect otherwise isolated habitat patches – They may be helpful or harmful to fragmented populations • Corridors can promote dispersal and reduce inbreeding in declining populations Figure 38.10C Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 38.11 Restoring degraded habitats is a developing science • Restoration ecology uses ecological principles to develop ways to return degraded ecosystems to conditions as similar as possible to their natural, predegraded state • There are two strategies in restoration ecology – Bioremediation – Augmentation Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Bioremediation is the use of living organisms to detoxify polluted ecosystems – These organisms are usually prokaryotes, fungi, or plants – These lichens are concentrating mining wastes Figure 38.11A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Augmentation of ecosystem processes involves resupplying an area with key factors that have been removed • Encouraging the growth of plants that thrive on nutrient-poor soils can hasten the rate of recovery of some tropical areas – In Puerto Rico, the legume Albizia helped set the stage for recolonization by native species Figure 38.11B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 38.12 Sustainable development is an ultimate goal • In numbers, geographic range, and capacity to alter the biosphere, our species is clearly one of the most successful ones ever to inhabit planet Earth • Human attitudes and environmental awareness are of utmost importance in the search for solutions to the biodiversity crisis Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The gray-headed flying fox symbolizes the biodiversity crisis • Habitat destruction and the killing of animals as pests has reduced the population 75% in the past 25 years • Further decrease could endanger this species and hurt its ecological role in maintaining forest diversity by pollination and seed dispersal Figure 38.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Understanding the biosphere's limits and vulnerability and our own linkages to the natural world may help us make decisions that lead to a sustainable future Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings