Population Ecology 1 CHAPTER 9 POPULATION ECOLOGY ..., Schemes and Mind Maps of Dynamics

Download Population Ecology 1 CHAPTER 9 POPULATION ECOLOGY ... and more Schemes and Mind Maps Dynamics in PDF only on Docsity! CHAPTER 9 POPULATION ECOLOGY Describe the various types of population distribution patterns that can occur in nature and comment on. which is most common and why. Define birth rate, death rate, immigration, and emigration. Write an equation to mathematically describe the relationship between these rates and the rate of population change. Define limiting factor. Give an example of a resource that would be limiting in an ecosystem. Define exponential growth. Compare a J-shaped growth curve with an S-shaped growth curve and comment on the factors that produce the sigmoid (S-shaped) curve. Define carrying capacity and explain what determines the carrying capacity of an ecosystem. Explain density-dependent population controls and density-independent population controls. List the four general types of population fluctuations in nature. Indicate which of these is most common. Discuss the relationships between predators and prey and the possible interactions upon each other. ). Define r-selected species and K-selected species and compare the two. Give an example for each type of species reproductive pattern. . Describe the three general types of survivorship curves in nature. . Explain the genetic effects on a population that has undergone bottleneck, genetic drift, or inbreeding due to isolation of the population. . List the nine major ways that humans have altered natural ecosystems and comment on the effects of these alterations for the future of the planet. Key Terms (Terms are listed in the same font as they appear in the text.) population dynamics (p. 164) size (p. 164) density (p. 164) age distribution (p. 164) population distribution (p. 164) dispersion (p. 164) clumping (p. 164) uniform dispersion (p. 164) random dispersion (p. 164) births (p. 164) deaths (p. 164) immigration (p. 164) emigration (p. 164) age structure (p. 164) prereproductive stage(p. 164) reproductive stage (p. 164) postreproductive stage (p. 164) biotic potential (p. 165) intrinsic rate of increase (r) (p. 165) Population Ecology environmental resistance (p. 165) carrying capacity (K) (p. 165) exponential growth (p. 166) logistic growth (p. 166) overshoots (p. 166) reproductive time lag (p. 166) dieback (crash) (p. 166) population density (p. 167) density-independent population controls (p. 167) density-dependent population controls (p. 167) bubonic plaque (p. 167) stable population fluctuations (p. 167) irruptive population fluctuations (p. 167) cyclic fluctuations (p. 167) irregular fluctuations (p. 167) top-down control (p. 168) bottom-up control (p. 168) asexual reproduction (p. 169) sexual reproduction (p. 169) r-selected species (p. 169) opportunists (p. 169) K-selected species (p. 169) life expectancies (p. 170) survivorship curve (p. 170) late loss curves (p. 170) early loss curves (p. 170) constant loss curves (p. 170) life table (p. 170) founder effect (p. 171) demographic bottleneck (p. 171) genetic drift (p. 171) inbreeding (p. 171) metapopulations (p. 171) monoculture (p. 172) opportunist species (p. 172) pests (p. 172) pathogens (p. 172) Chapter 9: Learning Log: Answer questions 2-18 on a separate piece of paper for extra credit points on population test. 1. Define the boldfaced terms in this chapter. (OMIT) 2. Explain how the populations of southern sea otters and kelp interact and why the southern sea otter is considered a keystone species. 3. What is population dynamics? Why are the populations of most species found in clumps or groups? 4. What four factors affect population change? Write an equation showing how population change is related to births, deaths, immigration, and emigration. 5. What is the biotic potential of a population? What are four characteristics of a population with a high intrinsic rate of increase (r) ? 6. What are environmental resistance and carrying capacity? How do biotic potential and environmental resistance interact to determine carrying capacity? 7. Distinguish between exponential and logistic growth of a population, and give an example of each type. 8. How can a population overshoot its carrying capacity, and what are the consequences of doing this? 9. Distinguish between density-dependent and density-independent factors that affect a population's size, and give an example of each. 10. Distinguish among stable, irruptive, irregular, and cyclic forms of population change. 1. Distinguish between top-down control and bottom-up control of a population’s size. Use these concepts to describe the effects of the predator-prey interactions between the snowshoe hare and the Canadian lynx on the population of each species. 12. Distinguish between asexual reproduction and sexual reproduction. What are the disadvantages and advantages of sexual reproduction? 13. List the characteristics of (a) r-selected or opportunist species and (b) K-selected or competitor species, and give two examples of each type. Under what environmental conditions are you most likely to find (a) r-selected species and (b) K-selected species? 14. What is a survivorship curve, and how is it used? List three general types of survivorship curves, and give an example of a species with each type. 15. How can genetic diversity affect the survival of small, isolated populations? Distinguish between the founder effect, demographic bottleneck, and genetic drift. What is a metapopulation? 16. List nine potentially harmful ways in which humans modify natural ecosystems. 17. List four principles of sustainability observed in natural systems and describe how they can be adapted for developing more sustainable human societies. 18. List four guidelines we could use to help us live more sustainably. 2 Chapter 9 9-3 Effects of Genetic Variations on Population Size A. Variations in genetic diversity can affect the survival of small, isolated populations. 1. 2. Several factors can play a role in loss of genetic diversity and survival of a small population. The founder effect is when a few individuals move to a new location that is isolated from the original population. There is limited genetic diversity in such a population. A demographic bottleneck occurs when only a few individuals survive a catastrophe. Genetic drift is a third factor and involves random changes in gene frequencies in a population. This may help or hurt the survival of the population. Inbreeding occurs when members of a small population mate one another; this may increase the numbers of defective genes in a population. B. Metapopulations occur where some mobile populations occasionally exchange genes when some members get together. Conservation biologists use this information to establish migration routes that will enhance population size, genetic diversity, and survival of related local populations. 9-4 Human Impacts on Natural Systems: Learning from Nature A. Humans have altered nature in ways that threaten the survival of many species, including our own species. 1. 2. Humans have directly affected changes on about 83% of the earth’s land surface. Humans have altered nature to meet needs and wants in nine major ways. a. Destruction, fragmentation, and degrading of wildlife habitats have reduced biodiversity. b. The simplification and homogenization of natural ecosystems by clearing land and planting a single species (monoculture) reduces numbers of species and interactions. Opportunistic species and pest organisms are costing time, energy, and money to control. Invasion of pathogenic organisms is another threat. c. Destruction of the earth’s net primary productivity is a third type of alteration. d. Certain types of intervention have unintentionally strengthened pest species and disease- causing bacteria. e. Some predator species have been deliberately eliminated from ranching areas. f. Alterations have occurred due to the introduction of nonnative or new species into an ecosystem. g. A number of renewable resources have been over-harvested, such as overgrazing of grasslands, over-hunting of wildlife, and pumping out aquifers for freshwater faster than they can recharge. h. Some human activities also interfere with normal chemical cycling and energy flows in ecosystems. i. Human-dominated ecosystems are increasingly dependent on nonrenewable energy from. fossil fuels that produce pollution and add greenhouse gases to the atmosphere. Alteration of natural ecosystems needs to be slowed down, and we need to maintain a balance between simplified, human-altered ecosystems and more complex, natural ecosystems. B. By mimicking four major ways that nature has adapted and sustained itself, we can develop more sustainable economies. 1. 2. We are totally dependent on the sun and Earth for life. We are an expendable species. Everything is interconnected and interdependent. What connections are strongest, most important, and most vulnerable are those that we must discover. Any intrusion into nature has unexpected and unintended side effects. We must not deplete and degrade the earth’s natural capital. Population Ecology 5 Summar: 1. Population changes in size, density, makeup, and distribution in response to environmental stress, but there is no direct relationship between the stressors and the population characteristics. Populations distributed throughout a habitat vary from species to species. The age of a population may influence its size directly. The carrying capacity is determined by biotic potential and environmental resistance. 2. Reproductive patterns in species are influenced by ample resources and limited resources. Once resources become limited, the population must decrease over time. The patterns among specific species vary, but there are four general types of population fluctuations: stable, irruptive, cyclic, and irregular. 3. If a population is fairly large, genetic diversity will be fairly constant, and the size of the population will be maintained. If a population is small and/or isolated, limited genetic diversity will threaten it. If a few individuals survive a catastrophe, they may be unable to rebuild the population. Inbreeding and genetic drift also influence a population’s viability. 4. Human activities and the use of technology now threaten the survival of many species and may affect our own quality of life. We have reduced biodiversity, homogenized natural ecosystems, wasted/destroyed the earth’s net primary productivity, strengthened some pest species and disease-causing bacteria, eliminated most predators, introduced nonnative species into ecosystems, overharvested renewable resources, interfered with chemical cycling and energy flows in ecosystems, and become dependent on nonrenewable resources. 5. We must maintain a balance between human-altered ecosystems and natural ecosystems. We must implement and live the spirit of these four guidelines: ..We are totally dependent on the sun and the earth. Everything is interdependent. . Anything we do will have consequences. ..We must live off the biological income of the earth’s natural capital, not squander it. 6 Chapter 9