5-1 How Populations Grow

Transcription

1 5-1 How Populations Grow How? (In general ecological terms.) Specifically, within populations what two primary factors determine the rate of growth and how are they related? What are two additional factors that affect population size? What are Sea Otters an example of? Diagram a simple food chain including Otters, Kelp, and Sea Urchins. Define keystone species and relate it to this food chain. How is this an example of top-down control (in contrast to bottom-up)? 39

2 Measuring Population Human Population Density In mathematical terms, how is population density measured and expressed? In the figure above, what does a high human population density mean? For this example map, we are not given the unit of area, so what do you think a population density of 1000 means? The map above shows how the distribution of African Elephants has changed over time. The shaded areas show how the ranges of many separate populations have diminished. Define population range. 40

3 Exponential Growth Exponential Growth How would you describe the shape indicative of exponential growth when plotted on a graph? Why do you think the authors chose to compare the exponential growth of Bacteria to Elephants? Define population growth rate. Define exponential growth. In exponential growth, as the population grows, what happens to the growth rate? What is exponential growth also known as? In the graph at left, what was the doubling time? What has been the environmental impact of human 41 population growth?

4 Logistic Growth How would you describe the shape indicative of logistic growth when plotted on a graph? Define logistic growth. In logistic growth, what eventually happens to the growth rate? Define limiting factor including a few examples. As a limiting factor decreases, what increases between individuals in a population? Define carrying capacity. Does the population size stay exactly at the carrying capacity? Explain! On the graph above, label the lag, exponential, and logistic phases. Note that this graph shows human population projected to the year What phase is human population currently in? What do you think is/will limit human population growth? 42

5 Density-Dependent Factors Predator-Prey Relationship Wolf and Moose Populations on Isle Royale Moose Wolves Based on this graph, how would you describe the Other Density-Dependent Factors? relationship between predator and prey in terms of their populations? 1. Is this relationship a biotic, or abiotic factor? Define density-dependent factor. 2. Are these factors biotic, abiotic, or both? 3. What do you think were the density-dependent factors 4. that caused the wolf population to crash in 1980 and the Moose population to crash after 1995? 5. List 5 density-dependent factors at left. 43

6 5-3 Human Population Growth Billions of People Add arrows and labels for the Haber Process (fertilizer) and modern medicine. Does this graph show exponential growth? (vaccination) What limited human population prior to 3500 BC? What limited human population after 3500 BC? When it becomes logistic, and it has/will, what may be the limiting factor? 44

7 Climate Change What appears to be the cause and effect relationship in this series of data? What effect do you think this will have on the distribution of biomes and species survival on Earth? What does this have to do with species tolerance? Do you recognize the connection to human population growth? 45

8 Global Climate Change From a recent study of lake sediments... On average, the region cooled at a rate of 0.2C per millennium until about Since then, it has warmed by about 1.2C. 46

9 Patterns of Population Growth Define the demographic transition. What are examples of countries that have or are undergoing this transition? Stage 1 is before transition, stage 2 during and stage 3 after. What do you think causes the decrease in death rate during stage 2? What do you think causes the decrease in birth rate? 47 How does this relate to global human population growth?

10 Age Structure Diagram Following Demographic Transition Rwandan Population 80+ Males U.S. Population 80+ Females Females Males Age (years) Age (years) Percentage of Population Percentage of Population Generally, what is the difference between these two countries? Which country has undergone demographic transition and how can you tell from the diagram? Are either of these countries increasing their population exponentially? If so, which one? 48

11 Future Population Growth Note the projection to the year According to this graph, what is the carrying capacity of the Earth for humans? From the table, what is happening and is projected to happen to the global human population growth rate? Why? Our population is now around 7.5 billion. Do you want to live on a planet with 9 billion people? 11 billion??? 49

12 6-1 A Changing Landscape Why? How? (List) Where is this? What is it an example of? 50

13 6-2 Renewable and Nonrenewable Resources Fish, along with other oceanic resources, are considered a commons. Define commons in this context. Search and explain The Tragedy of the Commons. Who regulates a commons? What negative outcome does this allow for? 51

14 Air Resources Chemical Transformation Nitric acid Sulfuric acid Emissions to Atmosphere Dry Fallout Nitrogen oxides Sulfur dioxide Industry Transportation Condensation Precipitation Particulates Acid rain, fog, Gases snow, and mist Ore smelting Power generation What general environmental problem does this represent? What specific environmental problem? Just as the oceans, the atmosphere is a. What is the greatest source of nitrogen oxides, specifically? Sulfur dioxide? How strong are nitric and sulfuric acids? In which ecosystems does acid precipitation have its greatest impact? The source of this problem is the same as what other environmental problem? What do you think should be done? 42

15 The Value of a Healthy Biosphere The table title is Ecosystem Services. Services for who? Is it possible for humans to perform all of these services for ourselves on a local or global scale? How much would it cost? Then what must we do? 53