Chapter 38 Conservation Biology

Transcription

1 Chapter 38 Conservation Biology Introduction Over the past century, wild tiger populations have been reduced from about 100,000 to 3,200. Tigers are threatened by declining habitat, poaching, and human populations encroaching into their habitat. PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey Lecture by Edward J. Zalisko Figure 38.0_1 Figure 38.0_2 Chapter 38: Big Ideas The Loss of Biodiversity Conservation Biology and Restoration Ecology THE LOSS OF BIODIVERSITY 38.1 Loss of biodiversity includes the loss of ecosystems, species, and genes Biodiversity has three levels: 1. ecosystem diversity, 2. species diversity, and 3. genetic diversity. 1

2 38.1 Loss of biodiversity includes the loss of ecosystems, species, and genes Figure 38.1A As natural ecosystems are lost, so are essential services, including productivity of natural environments for human food supplies and the purification of water used by cities. Video: Coral Reef 38.1 Loss of biodiversity includes the loss of ecosystems, species, and genes Figure 38.1B 100% At present, scientists have described and formally named about 1.8 million species. It is difficult to estimate species loss. Species loss may be 1,000 times higher than at any time in the past 100,000 years. Extirpation is the loss of a single population of a species. Extinction is the irreversible loss of all populations of a species. Percentage of species assessed 80% 60% 40% 20% 0% Mammals (N 4,653) Birds Amphibians Freshwater (N 9,933) (N 4,688) fishes (N 2,689) Reptiles (N 1,429) Lowest risk Near threatened Threatened Extinct 38.1 Loss of biodiversity includes the loss of ecosystems, species, and genes Figure 38.1C Because of the network of community interactions among populations of different species within an ecosystem, the loss of one species can negatively affect the species richness of an ecosystem. 2

3 38.1 Loss of biodiversity includes the loss of ecosystems, species, and genes Figure 38.1D Genetic diversity of a species is reduced if local populations are lost and the total number of individuals declines CONNECTION: Habitat loss, invasive species, overharvesting, pollution, and climate change are major threats to biodiversity Figure 38.2A Human alteration of habitats poses the greatest threat to biodiversity. Habitation alteration is caused by agriculture, urban development, forestry, mining, and environmental pollution CONNECTION: Habitat loss, invasive species, overharvesting, pollution, and climate change are major threats to biodiversity Figure 38.2B Invasive species rank second behind habitat destruction as a threat to biodiversity. Invasive species compete with native species, prey on native species, and parasitize native species. 3

4 38.2 CONNECTION: Habitat loss, invasive species, overharvesting, pollution, and climate change are major threats to biodiversity Figure 38.2C Overexploitation is the third major threat to biodiversity. Overharvesting has threatened rare trees, reduced populations of tigers, Galápagos tortoises, whales, and rhinoceroses, and depleted wild populations of game fish CONNECTION: Habitat loss, invasive species, overharvesting, pollution, and climate change are major threats to biodiversity Figure 38.2D Human activities produce diverse pollutants that may affect ecosystems far from their source. The water cycle transfers pollutants from terrestrial to aquatic ecosystems. The release of chemicals into the atmosphere promoted the thinning of the ozone layer. Biological magnification concentrates synthetic toxins that cannot be degraded by microorganisms. Figure 38.2E Concentration of PCBs Herring gull eggs 124 ppm 38.3 CONNECTION: Rapid warming is changing the global climate The scientific debate about global warming is over. Lake trout 4.83 ppm Increased global temperatures caused by rising concentrations of greenhouse gases are changing climate patterns with grave consequences. Smelt 1.04 ppm Global temperature has risen 0.8 C in the last 100 years. 0.6 C of that increase occurred in the last three decades. 2 to 4.5 C increases are likely by the end of the 21st century. Temperature increases are not distributed evenly. Zooplankton ppm Phytoplankton ppm Precipitation patterns are changing too. 4

5 Figure 38.3A Figure 38.3B Figure 38.3B_1 Figure 38.3B_ Figure 38.3B_ CONNECTION: Human activities are responsible for rising concentrations of greenhouse gases Much of the rapid warming is the result of burning fossil fuels. Atmospheric CO 2 did not exceed 300 ppm for 650,000 years. The preindustrial concentration was below 300 ppm. Atmospheric CO 2 is approximately 385 ppm today High levels of methane and nitrous oxide also trap heat. 5

6 Figure 38.4A 400 2,000 Figure 38.4B CO 2 (ppm), N 2 O (parts per billion) Carbon Dioxide (CO 2 ) Nitrous Oxide (N 2 O) Methane (CH 4 ) 1,800 1,600 1,400 1,200 1, CH 4 (parts per billion) Photosynthesis Respiration Atmosphere Combustion of fossil fuels Ocean Year 38.5 Global climate change affects biomes, ecosystems, communities, and populations Figure 38.5A Climate change in western North America has spawned catastrophic wildfires Global climate change affects biomes, ecosystems, communities, and populations Figure 38.5B The greatest impact of global climate change is affecting organisms that live at high latitudes and high elevations. 6

7 38.5 Global climate change affects biomes, ecosystems, communities, and populations Warming oceans threaten coral reef communities. Earlier arrival of warm temperatures in the spring is disturbing ecological communities. Birds and frogs have begun their breeding periods earlier. Migratory birds may experience mismatches, arriving after peak food availability has already passed Global climate change affects biomes, ecosystems, communities, and populations Climate change has also increased the range of disease-carrying mosquitoes and enabled bark beetles to reproduce faster, promoting the destruction of millions of acres of conifers in western North America EVOLUTION CONNECTION: Climate change is an agent of natural selection Phenotypic plasticity has minimized the impact of global climate change on some species, and cases of microevolutionary changes have been observed. The rapidity of the environmental changes makes it unlikely that evolutionary processes will save many species from extinction EVOLUTION CONNECTION: Climate change is an agent of natural selection In Europe, the great tit bird has shifted its breeding season earlier, in an example of directional selection, favoring individuals that lay their eggs sooner, and better matching the earlier emergence of caterpillars. Figure 38.6A 38.6 EVOLUTION CONNECTION: Climate change is an agent of natural selection In the Yukon Territory of Canada, where the spring temperatures have increased by about 2 C, red squirrels have begun breeding earlier in the spring. 7

8 Figure 38.6B CONSERVATION BIOLOGY AND RESTORATION ECOLOGY 38.7 Protecting endangered populations is one goal of conservation biology Conservation biology is a goal-driven science that seeks to understand and counter the rapid loss of biodiversity. Some conservation biologists direct their efforts at protecting populations and increasing endangered populations. Threats posed by human activities are also assessed Protecting endangered populations is one goal of conservation biology The black-footed ferret in the United States is one of three ferret species worldwide and the only ferret found in North America, was reduced to just 18 individuals, has been bred in captivity, and was reintroduced into the wild. Figure 38.7A 38.7 Protecting endangered populations is one goal of conservation biology In Hawaii, the silversword plants once abundant on the cinder cone of the volcano Mauna Kea were bred in greenhouses and reintroduced to reestablish wild populations. 8

9 Figure 38.7B 38.8 Sustaining ecosystems and landscapes is a conservation priority Conservation efforts are increasingly aimed at sustaining ecosystems and landscapes, a regional assemblage of interacting ecosystems. Landscape ecology is the application of ecological principles to the study of the structure and dynamics of a collection of ecosystems. Figure 38.8A 38.8 Sustaining ecosystems and landscapes is a conservation priority Edges between ecosystems have distinct sets of features and species. The increased frequency and abruptness of edges caused by human activities can increase species loss. Movement corridors connecting isolated habitats may be helpful to fragmented populations. Figure 38.8B Figure 38.8C 9

10 38.9 Establishing protected areas slows the loss of biodiversity To establish parks, wilderness areas, and other legally protected reserves, conservation biologists are applying their understanding of population, ecosystem, and landscape dynamics Establishing protected areas slows the loss of biodiversity Choosing locations for protection often focuses on biodiversity hot spots, relatively small areas with a large number of endangered and threatened species, and an exceptional concentration of endemic species, those that are found nowhere else. Figure 38.9A 38.9 Establishing protected areas slows the loss of biodiversity Migratory species pose a special problem for conservationists. Monarch butterflies occupy many areas. Equator Sea turtles travel great distances. Figure 38.9B Figure 38.9_UN 10

11 38.10 Zoned reserves are an attempt to reverse ecosystem disruption Zoned reserves are undisturbed wildlands surrounded by buffer zones of compatible economic development. Costa Rica has established many zoned reserves. Figure 38.10A NICARAGUA COSTA RICA Ecotourism PANAMA is travel to natural areas for tourism and recreation and has become an important source of revenue for conservation efforts. National Parks and Reserves Figure 38.10B CONNECTION: The Yellowstone to Yukon Conservation Initiative seeks to preserve biodiversity by connecting protected areas The Yellowstone to Yukon Conservation Initiative created a string of parks and reserves in a 3,200-km wildlife corridor, extends from Alaska south across Canada to northern Wyoming, included the reintroduction of wolf populations, considered a keystone species in this region, and sparked angry protests from some ranchers. Figure 38.11A Figure 38.11A_1 YUKON TERRITORY NORTHWEST TERRITORIES Whitehorse ALBERTA YUKON TERRITORY Whitehorse NORTHWEST TERRITORIES PACIFIC OCEAN BRITISH COLUMBIA Calgary Vancouver Spokane WASHINGTON MONTANA Bozeman ALBERTA OREGON IDAHO Jackson WYOMING 11

12 Figure 38.11A_2 Figure 38.11B PACIFIC OCEAN BRITISH COLUMBIA Calgary Vancouver Spokane WASHINGTON MONTANA Bozeman OREGON IDAHO Jackson WYOMING Figure 38.11C CONNECTION: The study of how to restore degraded habitats is a developing science Restoration ecology uses ecological principles to restore degraded areas to their natural state, a process that may include detoxifying polluted ecosystems, replanting native vegetation, and returning waterways to their natural course CONNECTION: The study of how to restore degraded habitats is a developing science Large-scale restoration projects attempt to restore damaged landscapes. Figure 38.12A Widened canal Water control structure remaining The Kissimmee River Restoration Project in Florida is restoring river flow and wetlands and improving wildlife habitat. Water control structure removed River channel restored Canal backfilled Kissimmee River Floodplain Water control structure to be removed in Phase 2 Phase 1 completed FLORIDA 0 10 Miles 12

13 Figure 38.12B Sustainable development is an ultimate goal Sustainable development seeks to improve the human condition while conserving biodiversity, depends on increasing and applying ecological knowledge, and values our linkages to the biosphere. Former canal Sustainable development is an ultimate goal Figure We are most likely to save what we appreciate and appreciate what we understand. Now is the time to aggressively pursue more knowledge about life and work toward long-term sustainability. You should now be able to You should now be able to 1. Describe the three components of biodiversity. 2. Describe the greatest current threats to biodiversity, providing examples of each. 3. Describe the process of biological magnification. 4. Describe the causes and consequences of global warming. 5. Explain why the efforts to save the black-footed ferret and silversword plant from extinction are a good model for future conservation efforts. 6. Describe the goals of landscape ecology. Describe the significance of edges and movement corridors in maintaining biodiversity. 7. Describe the significance of biodiversity hotspots. 8. Explain how zoned reserves are being used to protect ecosystems. 9. Describe the goals of the Yukon to Yellowstone Initiative. 13

14 You should now be able to Figure 38.UN Describe the goals and methods of restoration ecology. 11. Explain why sustainable development should be the ultimate goal for the long-term maintenance of human societies and the ecosystems that support them. Ecosystem diversity Species diversity Genetic diversity Figure 38.UN02 Conservation biology seeks to conserve may involve (a) ecosystems and landscapes may be protected in attempt to restore which uses nature reserves may be restoration projects ATLANTIC OCEAN FLORIDA (c) to (d) which support sustainable development GULF OF MEXICO detoxify or replenish degraded ecosystems 14