Transcript Chapter 8
Population Dynamics, Carrying Capacity, and Conservation Biology G. Tyler Miller, Jr.’s Environmental Science 10th Edition Chapter 8 Key Concepts Environmental factors affecting populations Role of predators in controlling populations Reproductive patterns and species survival Conservation biology Human impacts on populations Lessons about sustainable living Sea Otters: Back from the Brink of Extinction? Keystone species Importance of otters Pollution effects Orcas Fig. 8-1, p. 160 Population Dynamics and Carrying Capacity Population dynamics Biotic potential (intrinsic rate of increase [r]) Environmental resistance Carrying capacity (K) Minimum viable population (MVP) Exponential and logistic population growth Dispersion Patterns for Organisms Fig. 8-2 p. 161 Factors Affecting Population Size Fig. 8-3, p. 162 Exponential and Logistic Population Growth Fig. 8-4, p. 163 Logistic Growth of Sheep Population Number of sheep (millions) 2.0 1.5 1.0 .5 1800 1825 1850 1875 Year 1900 1925 Fig. 8-5, p. 163 When Population Size Exceeds Carrying Capacity Overshoots Reproductive time lag Diebacks (crashes) Exponential Growth, Overshoot and Population Crash of Reindeer Number of reindeer 2,000 1,500 1,000 500 1910 1920 1930 Year 1940 1950 Fig. 8-6, p. 164 Population Density Effects Density-independent controls Density-dependent controls Natural Population Curves Fig. 8-7 p. 164 The Role of Predation in Controlling Population Size Predator-prey cycles Top-down control Bottom-up control Fig. 8-8, p. 165 Reproductive Patterns and Survival Asexual reproduction Sexual reproduction r-selected species K-selected species Fig. 8-10 p. 167 Positions of r-selected and K-selected Species on Population Growth Curve Number of individuals Carrying capacity K K species; experience K selection r species; experience r selection Time Fig. 8-9, p. 166 r-Selected Species cockroach dandelion Many small offspring Little or no parental care and protection of offspring Early reproductive age Most offspring die before reaching reproductive age Small adults Adapted to unstable climate and environmental conditions High population growth rate (r) Population size fluctuates wildly above and below carrying capacity (K) Generalist niche Low ability to compete Early successional species Fig. 8-10a, p. 167 K-Selected Species elephant saguaro Fewer, larger offspring High parental care and protection of offspring Later reproductive age Most offspring survive to reproductive age Larger adults Adapted to stable climate and environmental conditions Lower population growth rate (r) Population size fairly stable and usually close to carrying capacity (K) Specialist niche High ability to compete Late successional species Figure 8-10b, p. 167 Survivorship Curves Age Fig.8-11, p. 167 Conservation Biology: Sustaining Wildlife Populations What is conservation biology? Which species are endangered? How are ecosystems functioning? How can ecosystems be sustained? Principles of conservation biology Aldo Leopold’s ethical principles Bioinformatics Human Impacts on Ecosystems Habitat degradation and fragmentation Ecosystem simplification (monocultures) Wasting Earth’s primary productivity Genetic resistance Eliminating predators Introducing nonnative species Overharvesting renewable resources Interfering with cycling and flows in ecosystems Human Footprint on Earth’s Land Surface Fig. 8-12, p. 169 Learning Sustainability from Nature Dependence on nature Interdependence Unpredictability Limited resources Recycle wastes See Connections p. 170 Four Principles of Sustainability PRINCIPLES OF SUSTAINABILITY Fig. 8-13, p. 170 Principles of Sustainability How Nature Works Solutions: Implications of the Principles of Sustainability Runs on renewable solar energy. Recycles nutrients and wastes. There is little waste in nature. Uses biodiversity to maintain itself and adapt to new environmental conditions. Controls a species' population size and resource use by interactions with its environment and other species. Fig. 8-14, p. 171 Lessons for Us Rely mostly on renewable solar energy. Prevent and reduce pollution and recycle and reuse resources. Preserve biodiversity by protecting ecosystem services and preventing premature extinction of species. Reduce births and wasteful resource use to prevent environmental overload and depletion and degradation of resources.