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Transcript
“Population Ecology” Chapter 4 Section 1 I. Population Dynamics • A. Population Characteristics: – 1. Population Density – 2. Spatial Distribution – 3. Growth rate B. Population Density 1. The number of organisms per unit area. C. Dispersion • 1. The pattern of spacing of a population within an area • 2. One limiting factor for population dispersion is availability of food D. Spatial Distribution • 1. No population occupies all habitats in the biosphere • 2. Example: – A. Alabama cave fish – found only in Key Cave by Pickwick Lake (no where else on Earth!) – B. Dolphins – found in most oceans II. Population Limiting Factors A. Keep a population from increasing indefinitely -Example: Decreasing food supply will shrink a population Fact: Every 3.6 seconds someone dies of hunger. 75% of them are children. B. Density-Independent Factors, page 94 (Do not depend of number of members of population!) • 1. – – • 2. – – – • 3. – – Climate Temperature Precipitation Natural disaster Storms Drought Flooding Habitat disruption Fire Human impact C. Density-Dependent Factors, page 95 (Any factor that depends on number of members of a population!) • • • • • 1. 2. 3. 4. 5. Predation Disease Parasites Competition Food & Water III. Population Growth Rate A. Explains how fast a population grows 1. Natality – birth rate 2. Mortality – death rate B. Know emigration vs. immigration 1. Emigration – moving away from a population 2. Immigration – moving into a population C. Exponential growth • 1. Population growth is slow at first – Lag • 2. Then, rate of growth increases rapidly due to total number of members – Exponential • 3. On a graph this is known as a “J” curve! Population growth is exponential. D. Logistic Growth • 1. Occurs when growth slows or stops following exponential growth at carrying capacity. • 2. Increase stops when births are less than deaths or emigration exceeds immigration • 3. On a graph this is known as “S” curve 4. Carrying Capacity is the number of organisms of one species an environment can support. • 5. If a population is under the carrying capacity births will exceed deaths until the carrying capacity is reached. • • 6. If a population exceeds the carrying capacity, deaths will exceed births until the carrying capacity is reached. D. R-strategist - Rapid life-history pattern organisms (page 98) • • • • • • • 1. 2. 3. 4. 5. 6. 7. Reproduce rapidly. Produce many offspring. Have small bodies. Mature rapidly. Have short life spans. Can live in unstable environments. Biotic and abiotic factors fluctuate. E. K-strategist - Slow life-history pattern organisms (page 99) • • • • • • • 1. 2. 3. 4. 5. 6. 7. Reproduce slowly. Produce few offspring. Have large bodies. Mature slowly. Have long life spans. Need stable environments. Carrying-capacity changes little. 4,767 years 4,767 years, F. Human Population Growth (4.2, page 104) • 1. Zero population growth: birthrate = deathrate • 2. Age structure: the number of male and females in each age group (pre-reproductive, reproductive, and post-reproductive) Biodiversity Chapter Five Section One IV. What is biodiversity? • A. Variety of life!!! • B. Importance to nature – 1. Complex relationships exist among organisms – 2. The loss of a species (extinction) affects many other species • Remember food webs!!!!! 3. Life Depends on life!!!!! C. Biodiversity = Stability D. Three Types of Biodiversity: 1. Genetics 2. Species 3. Ecosystem 1. Genetic Diversity – variety of inherited genes 2. Species Diversity – number of different species 3. Ecosystem Diveristy: Variety of ecosystems in the Biosphere E. Importance to People • 1. We are living and we depend on other living things. • 2. Food Sources 3. Medicines **25% are plant derived** V. Loss of Biodiversity • A. Extinction 1. Background (gradual) 2. Mass (short) Miss Waldron's Red Colobus (Monkey) B. Save the Polar Bears ~The Eagle is a success story! C. Endangered Species Endangered Species Act of 1973 • Protects Endangered and Threatened Species. • WHAT LEADS TO THE BIGGEST LOSS OF BIODIVERSITY???? VI. Threats to Biodiversity • A. Habitat Loss • (Biggest threat to biodiversity.) B. Habitat Fragmentation – separation of ecosystem C. Habitat Degradation 1. Acid Precipitation 2. Ozone Depletion • Caused by CFCs. D. Water Pollution E. Land Pollution Example: DDT almost caused the extinction of the Bald Eagle in the continental US! DDT (dichlorodiphenyltrichloroethane) is an organochlorine insecticide which is a white, crystalline solid, tasteless, and almost odorless. F. Overexploitation Hunted for their Tusks G. Introduction of Exotic Species What is an Exotic Species? Water Hyacinth A species of organism that is not native to an area. Examples of Exotic Species Zebra Mussels Sea Lamprey on Trout Kudzu Feral pig How did they get here? • Intentionally • Favorite plants brought from the homeland to a new country. • Pig brought and released for food. • Accidentally • Fungus brought with plants from other counties. • Norway rats brought as stowaways on ships. Ox-eyed Daisy Are all Exotic Species Harmful? Not all exotic species should be considered harmful. Wheat and oats form the basis of the agricultural industry and supply a large proportion of the diet of the US. What are the Results of the Introduction of Harmful Invasive Species? Invasive species are responsible for significant ecosystem destruction all over the world. Purple Loosestrife Negative Impact According to a government report, "Invasive Plants are Changing the Landscape of America," Introduced species now comprise between 8 to 47 % of the total flora of most states. What is being done? A Unified Defense Against Invasive Species On February 3, 1999, Executive Order 13112 was signed establishing the National Invasive Species Council Dandelion