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Chapter 56 Conservation Biology and Restoration Ecology PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overview: The Biodiversity Crisis • Overview: The Biodiversity Crisis – Conservation biology integrates the following fields to conserve biological diversity at all levels • Ecology • Evolutionary biology • Physiology • Molecular biology • Genetics • Behavioral ecology Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Restoration Ecology • Restoration ecology applies ecological principles – In an effort to return degraded ecosystems to conditions as similar as possible to their natural state Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Losing Tropical Forests • Tropical forests – Contain some of the greatest concentrations of species – Are being destroyed at an alarming rate Figure 55.1 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The HUMAN Impact • Throughout the biosphere, human activities are altering ecosystem processes on which we and other species depend! • Rates of species extinction are difficult to determine under natural conditions • The current rate of species extinction is high and is largely a result of ecosystem degradation by humans • Humans are threatening Earth’s biodiversity Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Three Levels of Biodiversity • Biodiversity has three main components – Genetic diversity – Species diversity Genetic diversity in a vole population – Ecosystem diversity Species diversity in a coastal redwood ecosystem Figure 55.2 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Community and ecosystem diversity across the landscape of an entire region Levels of Biodiversity • Genetic diversity comprises – The genetic variation within a population – The genetic variation between populations • Species diversity – Is the variety of species in an ecosystem or throughout the biosphere • Ecosystem diversity – Identifies the variety of ecosystems in the biosphere – Is being affected by human activity Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Species Diversity • An endangered species – Is one that is in danger of becoming extinct throughout its range • Threatened species – Are those that are considered likely to become endangered in the foreseeable future • Conservation biologists are concerned about species loss – Because of a number of alarming statistics regarding extinction and biodiversity Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Biodiversity and Human Welfare • Human biophilia – Allows us to recognize the value of biodiversity for its own sake • Species diversity – Brings humans many practical benefits Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Benefits of Species and Genetic Diversity • Many pharmaceuticals – Contain substances originally derived from plants • The loss of species – Also means the loss of genes and genetic diversity • The enormous genetic diversity of organisms on Earth – Has the potential for great human benefit Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ecosystem Services • Ecosystem services encompass all the processes through which natural ecosystems and the species they contain help sustain human life on Earth • Ecosystem services include – Purification of air and water – Detoxification and decomposition of wastes – Cycling of nutrients – Moderation of weather extremes – And many others Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Four Major Threats to Biodiversity • Most species loss can be traced to four major threats – Habitat destruction – Introduced species – Overexploitation – Disruption of “interaction networks” Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Habitat Destruction • Human alteration of habitat – Is the single greatest threat to biodiversity throughout the biosphere • Massive destruction of habitat – Has been brought about by many types of human activity • In almost all cases – Habitat fragmentation and destruction leads to loss of biodiversity Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Introduced Species • Introduced species – Are those that humans move from the species’ native locations to new geographic regions (a) Brown tree snake, introduced to Guam in cargo • Introduced species that gain a foothold in a new habitat – Usually disrupt their adopted community Figure 55.6a, b Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings (b) Introduced kudzu thriving in South Carolina Overexploitation • Overexploitation refers generally to the human harvesting of wild plants or animals – At rates exceeding the ability of populations of those species to rebound • The fishing industry – Has caused significant reduction in populations of certain game fish Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Disruption of Interaction Networks • The extermination of keystone species by humans – Can lead to major changes in the structure of communities Figure 55.8 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Conservation Effort • Population conservation focuses on population size, genetic diversity, and critical habitat • Biologists focusing on conservation at the population and species levels – Follow two main approaches • Conservation biologists who adopt the smallpopulation approach – Study the processes that can cause very small populations finally to become extinct Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Extinction Vortex • A small population is prone to positivefeedback loops – That draw the population down an extinction vortex Small population Inbreeding Genetic drift Lower reproduction Higher mortality Reduction in individual fitness and population adaptability Figure 55.9 Smaller population Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Loss of genetic variability The Extinction Vortex • The key factor driving the extinction vortex – Is the loss of the genetic variation necessary to enable evolutionary responses to environmental change Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Minimum Viable Population Size • The minimum viable population (MVP) – Is the minimum population size at which a species is able to sustain its numbers and survive • A population viability analysis (PVA) – Predicts a population’s chances for survival over a particular time – Factors in the MVP of a population • A meaningful estimate of MVP – Requires a researcher to determine the effective population size, which is based on the breeding size of a population Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Declining-Population Approach • The declining-population approach – Focuses on threatened and endangered populations that show a downward trend, regardless of population size – Emphasizes the environmental factors that caused a population to decline in the first place • The declining-population approach requires that population declines be evaluated on a case-by-case basis – Involves a step-by-step proactive conservation strategy Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Case Study: Decline of the Red-Cockaded Woodpecker • Red-cockaded woodpeckers – Require specific habitat factors for survival – Had been forced into decline by habitat destruction (a) A red-cockaded woodpecker perches at the entrance to its nest site in a longleaf pine. Figure 55.13a–c (b) Forest that can sustain red-cockaded woodpeckers has low undergrowth. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings (c) Forest that cannot sustain red-cockaded woodpeckers has high, dense undergrowth that impacts the woodpeckers’ access to feeding grounds. Case Study: Decline of the Red-Cockaded Woodpecker • In a study where breeding cavities were constructed – New breeding groups formed only in these sites • On the basis of this experiment – A combination of habitat maintenance and excavation of new breeding cavities has enabled a once-endangered species to rebound Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Weighing Conflicting Demands • Conserving species often requires resolving conflicts – Between the habitat needs of endangered species and human demands Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Regional Conservation • Landscape and regional conservation aim to sustain entire areas of biodiversity • In recent years, conservation biology has attempted to sustain the biodiversity of entire communities, ecosystems, and landscapes • One goal of landscape ecology, of which ecosystem management is part – Is to understand past, present, and future patterns of landscape use and to make biodiversity conservation part of land-use planning Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Fragmentation and Edges • The structure of a landscape can strongly influence biodiversity • The boundaries, or edges, between ecosystems are defining features of landscapes • As habitat fragmentation increases and edges become more extensive, biodiversity tends to Figure 55.14a, b decrease Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings (a) Natural edges. Grasslands give way to forest ecosystems in Yellowstone National Park. (b) Edges created by human activity. Pronounced edges (roads) surround clear-cuts in this photograph of a heavily logged rain forest in Malaysia. Biological Hot Spots • Much of the focus on establishing protected areas – Has been on hot spots of biological diversity • Biodiversity hot spots are obviously good choices for nature reserves – But identifying them is not always easy Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Finding Biodiversity Hot Spots • A biodiversity hot spot is a relatively small area – With an exceptional concentration of endemic species and a large number of endangered and threatened species Terrestrial biodiversity hot spots Equator Figure 55.17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Philosophy of Nature Reserves • Nature reserves are biodiversity islands – In a sea of habitat degraded to varying degrees by human activity • One argument for extensive reserves – Is that large, far-ranging animals with lowdensity populations require extensive habitats Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Restoration Ecology • Restoration ecology attempts to restore degraded ecosystems to a more natural state • The larger the area disturbed – The longer the time that is required for recovery • One of the basic assumptions of restoration ecology – Is that most environmental damage is reversible • Two key strategies in restoration ecology – Are bioremediation and augmentation of ecosystem processes Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Bioremediation & Biological Augmentation • Bioremediation – Is the use of living organisms to detoxify ecosystems • Biological augmentation – Uses organisms to add essential materials to a degraded ecosystem Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Exploring Restoration • The newness and complexity of restoration ecology – Require scientists to consider alternative solutions and adjust approaches based on experience Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Sustainable Use • Sustainable development seeks to improve the human condition while conserving biodiversity • Facing increasing loss and fragmentation of habitats – How can we best manage Earth’s resources? Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Sustainable Biosphere Initiative • The goal of this initiative is to define and acquire the basic ecological information necessary – For the intelligent and responsible development, management, and conservation of Earth’s resources Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Biophilia and the Future of the Biosphere • Our modern lives – Are very different from those of early humans who hunted and gathered and painted on cave walls Figure 55.24a (a) Detail of animals in a Paleolithic mural, Lascaux, France Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Biophilia and the Future of the Biosphere • But our behavior – Reflects remnants of our ancestral attachment to nature and the diversity of life, the concept of biophilia Figure 55.24b (b) Biologist Carlos Rivera Gonzales examining a tiny tree frog in Peru Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Biophilia and the Future of the Biosphere • Our innate sense of connection to nature – May eventually motivate a realignment of our environmental priorities Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings