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Transcript
Population Dynamics Chapter 5 Describing Populations Geographic Range Density where they are located How many oragnisms live in a certain area Distribution How they are spread out in an area Three Patterns 1. 2. 3. Randomly Uniform Clumped Population Growth Populations are a group of organisms of the same species. Population Growth is the CHANGE in the size of a population with time. 4 Factors of Population Size 1. 2. 3. 4. Birth Rate Death Rate Immigration Emigration How Do Populations Grow? When graphing population numbers over time… Populations do not have linear growth. (straight line on a graph) Populations grow exponentially Exponential Growth occurs when the number of organisms increase at an increasing rate. This creates a population explosion, resulting in a J CURVE Logistic Growth 3 Phases of Growth Phase 1: Exponential Growth Phase 2 Growth Slows Phase 3 Growth Stops Populations are LIMITED by the environment Populations cannot grown indefinitely! Logistic population growth occurs when the growth rate decreases as the population reaches carrying capacity. Carrying capacity is the maximum number of individuals in a population that the environment can support. There are limiting factors in an environment Limiting Factors SLOW the growth of a population. Limiting Factors Acting separately or together, limiting factors determine the carrying capacity of an environment for a species. There are 2 types 1. Density Dependent 2. Density Independent Density-Dependent Factors Competition Food, water, space, sunlight Predation and Herbivory Parasitism and Disease Stress of Overcrowding Density-Independent Factors Hurricanes Drought Flood Change in weather patterns Wildfires Natural Disasters Independent Learning Complete a summary on page 136 in your textbook. What are some ways that the population can be controlled naturally? Which viewpoint to you agree with? Human Population Growth Thomas Malthus Suggested that only war, famine, and disease could limit human population. Competition = war Parasitism = disease Resources = famine His thinking greatly influenced Charles Darwin Analysis of Human Population Growth History Page 145 Answer the questions #1-3. Review 1. 2. 3. For tens of thousands of years the human population grew very slowly. About 500 years ago exponential growth began. The growth rate slowed at the second half of the 20th century. The population is still growing, but at a much slower rate. Harsh living conditions brought higher death rates in earlier human history. Human population grew more rapidly as advancements were made in manufacturing, nutrition, sanitation, and healthcare. These advancements decreased the death rate. Different countries have different birth rates, death rates, and age structures causing differences in world populations. Age structures can help scientists predict population growth. Answers will vary. Effects of Human Activity Humans affect the environments through Agriculture Development Industry Use of natural resources Renewable Non-Renewable Sustainable Development Preserves the ecosystem by meeting human needs naturally Using Our Resources Wisely Soil Resources Healthy soil supports agriculture and forestry Negative Impacts of Human Activities Removing Soil Soil Eroision Desertification Deforestation Dust Bowl of 1935 Freshwater Resources Water Pollution from industrial and agricultural chemicals, sewage and runoff. Biological Magnification – when a pollutant is absorbed into an organisms tissues and cannot be broken down. Mercury, PCB, DDT Biodiversity Total genetic variation of all organisms in a biosphere Benefits to society Medicine Agriculture Provision of goods and services Threats to Biodiversity Altered Habitats Hunting and Demand Non-Native Species Introduction Pollution Climate Change Conserving Biodiversity Protecting Individual Species Preserving Habitats and Ecosystems Changing Habits to Consciousness for Environment Group Activity Choose Case Study 1,2, or 3 What is the cause of this study? What is the effect of this study? What have you learned from this study?
